Page 385
     
 
  The Animal Kingdom  
 
   
 
  Animals (from Latin anima, meaning "breath" or "life") are members of the kingdom Animalia, one of the major categories of living things, the science of which is zoology. Animals are all heterotrophs (they obtain their energy from organic substances produced by other organisms); they have eukaryotic cells (the genetic material is contained within a distinct nucleus) bounded by a thin cell membrane rather than the thick cell wall of plants. Most animals are capable of moving around for at least part of their life cycle. In the past, it was common to include the single-celled protozoa with the animals, but these are now classified as protists, together with single-celled plants. Thus all animals are multicellular. The oldest land animals known date back 440 million years.  
 
   
 
  Classification  
 
   
 
  kingdom  
 
   
 
  The primary division in biological classification is the kingdom. At one time, only two kingdoms were recognized: animals and plants. Any organism with a rigid cell wall was a plant, and so bacteria and fungi were considered plants, despite their many differences. Today most biologists prefer a five-kingdom system, even though it still involves grouping together organisms that are probably unrelated.  
 
   
 
  phylum Kingdoms are made up of phyla. The vertebrates (animals with backbones or primitive precursors of these)—mammals, birds, reptiles, amphibians, fishes, and tunicates—belong to the phylum Chordata. The invertebrates (animals without backbones) are classified in various phyla including Echinodermata, containing starfish, sea urchins, and sea cucumbers; Mollusca, consisting of snails, slugs, mussels, clams, squid, and octopuses; Arthropoda, containing insects, spiders, millipedes, crabs, and shrimps; Annelida, Nematoda, and Platyhelminthes, containing the segmented worms, unsegmented worms, and flatworms respectively; Coelenterata, containing jellyfish, hydra, sea anemones, and coral; and Porifera, containing sponges.  
 
   
 
  There are more than 30 different animal phyla. The most recently identified is Cycliophora, which was described in 1995 and contains only one known species, Symbion pandora, a tiny invertebrate that lives in among the mouthparts of some lobsters.  
 
   
 
  class The phyla are made up of classes. For example, all mammals belong to the class Mammalia, all birds to the class Aves, and all insects to Insecta.  
 
   
 
  order Each class contains one or more related orders. For example, the horse, rhinoceros, and tapir families are grouped in the order Perissodactyla, the odd-toed ungulates, because they all have either one or three toes on each foot. By convention, the names of orders have the ending "-formes" in birds and fish, and "-a" in mammals, amphibians, reptiles, and other animals.  
 
   
 
  family An order breaks down into groups of related families. By convention, animal families all have the ending "-idea." For example, hummingbirds are grouped in the hummingbird family Trochilidae.  
 
   
 
  genus  
 
   
 
  Families contain groups of related genera. Each genus groups together species with many characteristics in common. Thus all doglike species (including dogs, wolves, and jackals) belong to the genus Canis (Latin "dog"). Species of the same genus are thought to be descended from a common ancestor species. By convention, genus names are given in italics, with an initial capital letter.  
 

 

 

 

   
Page 386
Classification of Living Things
Classification is the grouping of organisms based on similar traits and evolutionary histories. Taxonomy and systematics are the two sciences that attempt to classify living things. In taxonomy, organisms are generally assigned to groups based on their characteristics. In modern systematics, the placement of organisms into groups is based on evolutionary relationships among organisms. Thus, the groupings are based on evolutionary relatedness or family histories called phylogenies.
The groups into which organisms are classified are called taxa (singular, taxon). The taxon that includes the fewest members is the species, which consists of a single organism. Closely related species are placed into a genus (plural, genera). Related genera are placed into families, families into orders, orders into classes, classes into phyla (singular, phylum) or, in the case of plants and fungi, into divisions, and phyla into divisions or kingdoms. The kingdom level, of which five are generally recognized, is the broadest taxonomic group and includes the greatest number of species. The table below provides an example of the classification of an organism representative of the animal kingdom and the plant kingdom.
Taxonomic Common Kingdom Phylum/ Class Order Family Genus3
Species3              
Groups1   name     division2    
human Animalia Chordata Mammalia Primates Hominoidea Homo sapiens
Douglas fir Plantae Tracheophyta Gymnospermae Coniferales Pinaceae Pseudotsuga douglasü
1 Intermediate taxonomic levels can be created by adding the prefixes "super-" or "sub-" to the name of any taxonomic level.
2 The term division is generally used in place of phylum/phyla for the classification of plants and fungi.
3 An individual organism is given a two-part name made up of its genus and species names. For example, Douglas fir is correctly known as Pseudotsuga douglasü.


 

   
 
  species  
 
   
 
  Species are the lowest level in the system of biological classification. Each species is a distinguishable group of organisms that resemble each other or consist of a few distinctive types (as in polymorphism), and that can all interbreed to produce fertile offspring. A species is designated by the genus name followed by the species name, for example Canis lupus (wolf), with both the genus and species name given in italics.  
 
   
 
  A native species is a species that has existed in a country at least from prehistoric times; a naturalized species is one known to have been introduced by humans from another country, but which now maintains itself; while an exotic species is one that requires human intervention to survive.  
 
   
 
  Around 1.4 million species of living things have been identified so far, of which 750,000 are insects and 41,000 are vertebrates. It is estimated that one species becomes extinct every day through habitat destruction.  
 
Classification: The Influence of DNA Analysis
DNA analysis is changing the way we classify animals, and throwing new light on how they evolve. A good example is shown by findings concerning whale families. Researchers in Belgium and the United States have completed a detailed analysis of similar genes in 16 species of whales, an the results are at variance with the way these species have been traditionally classified.
Whales with teeth, such as the sperm whale and the dolphins, have previously been thought to be closely related and have been classified as such. However, comparing the DNA that codes for ribosomal RNA in whales shows that the sperm whales are more closely related to the baleen whales, which do not have teeth but which filter food from the sea.
The comparison also showed that the beaked whale, which has a few teeth, is only distantly related to the other whale families. The results were confirmed by comparison of the DNA sequence for myoglobin in different whale species.
the influence of DNA analysis on evolutionary theory
What does this mean? Well, it helps to fill in our understanding of how this important group evolved. One important point, for example, concerns echolocation, the ability of whales to navigate by listening to the echoes of sounds. According to traditional classification, baleen whales never had the ability to echolocate. The new classification implies that baleen whales have evolved from species that were able to echolocate, and have now lost the ability.


 

 

 

 

   
Page 387
   
 
  Mammals  
 
   
 
  The mammals comprise a large group of warm-blooded vertebrate animals characterized by having mammary glands in the female; these are used for suckling the young. Other features of mammals are hair (very reduced in some species, such as whales); a middle ear formed of three small bones (ossicles); a lower jaw consisting of two bones only; seven vertebrae in the neck; and no nucleus in the red blood cells.  
 
   
 
  There are over 4,000 species of mammals, adapted to almost every way of life. The smallest shrew weighs only 2 g/0.07 oz, the largest whale up to 140 metric tons/154 US tons. As with every other animal group, a number of mammal species are in danger of extinction from habitat loss and hunting. According to the Red List of endangered species published by the World Conservation Union (IUCN) for 1996, 25% of mammal species are threatened with extinction.  
 
   
 
  Mammals are divided into three groups: placental mammals (the largest group), such as humans, wolves, armadillos, bats, and shrews; marsupials, such as kangaroos, koalas, and wombats; and monotremes, such as platypuses and echidnas (spiny anteaters).  
 
   
 
  placental mammals  
 
   
 
  Most mammals are placental mammals, where the young develop inside the mother's body, in the uterus, receiving nourishment from the blood of the mother via the placenta. There is considerable variation among  
 
Major Invertebrate and Vertebrate Groups
Invertebrates  
Taxon1 Name Examples
 
 
  P  
 
Porifera all sponges
 
 
  P  
 
Cnidaria corals, sea anemones, Hydra, jellyfishes
 
 
  P  
 
Ctenophora sea gooseberries, comb jellies
 
 
  P  
 
Platyhelminthes flatworms, flukes, tapeworms
 
 
  P  
 
Nemertina nemertine worms, ribbon worms
 
 
  P  
 
Nematoda roundworms
 
 
  P  
 
Mollusca clams, oysters, snails, slugs, octopuses, squids, cuttlefish
 
 
  P  
 
Annelida ringed worms, including lugworms, earthworms, and leeches
 
 
  P  
 
Arthropoda (subdivided into classes below)
 
 
  C  
 
Arachnida spiders, ticks, scorpions, mites
 
 
  C  
 
Branchiopoda water fleas
 
 
  C  
 
Cirripedia barnacles
 
 
  C  
 
Malacostraca crabs, lobsters, shrimp, woodlice
 
 
  C  
 
Diplopoda millipedes
 
 
  C  
 
Chilopoda centipedes
 
 
  C  
 
Insecta silverfish, dragonflies, mayflies, stoneflies, cockroaches, earwigs, web spinners, termites, booklice, lice, grasshoppers, thrips, lace-wings, scorpion flies, caddis-flies, moths, butterflies, beetles, house flies, fleas, stylopids, ants, bees
 
 
  P  
 
Echinodermata sea stars, brittle stars, sea urchins, sand dollars, sea cucumbers
 
 
  P  
 
Hemichordata acorn worms, pterobranchs, graptolites
Vertebrates  
Taxon1 Name Examples
 
 
  C  
 
Agnatha (jawless fishes) lampreys, hagfishes
 
 
  C  
 
Chondricthyes (cartilaginous fishes) dogfish, sharks, rays, skates
 
 
  C  
 
Osteichthyes (bony fishes) salmon, catfishes, perches, flatfishes including flounder and halibut
 
 
  C  
 
Amphibia frogs, toads, newts, salamanders, caecilians
 
 
  C  
 
Reptilia tuatara, tortoises, turtles, lizards, snakes
 
 
  C  
 
Aves rheas, ostriches, moa, penguins, ducks, pheasants, gulls, swifts, kingfishers, sparrows, woodpeckers, pelicans, flamingoes, herons, falcons, cranes, divers, pigeons, parrots, cuckoos, owls
 
 
  C  
 
Mammalia duck-billed platypuses, echidnas, kangaroos, opossums, shrews, bats, dogs, seals, whales, dolphins, rats, rabbits, pigs, camels, deer, horses, tapirs, elephants, hyraxes, anteaters, manatees, pangolins, lemurs, monkeys, humans
1 P represents phylum; C represents class.


 

 

 

 

   
Page 388
Classification of Mammals
 
 
  Order  
 
Number
of species
Examples
Subclass: Prototheria (egg-laying mammals)
 
 
  Monotremata  
 
3
echidna, platypus
Subclass: Theria  
 
 
  Infraclass: Metatheria (pouched mammals)  
 
 
 
  Marsupiala  
 
266
kangaroo, koala, opossum
 
 
  Infraclass: Eutheria (placental mammals)  
 
 
 
  Rodentia  
 
1,700
rat, mouse, squirrel, porcupine
 
 
  Chiroptera  
 
970
all bats
 
 
  Insectivora  
 
378
shrew, hedgehog, mole
 
 
  Carnivora  
 
230
cat, dog, weasel, bear
 
 
  Primates  
 
180
lemur, monkey, ape, human
 
 
  Artiodactyla  
 
145
pig, deer, cattle, camel, giraffe
 
 
  Cetacea  
 
79
whale, dolphin
 
 
  Lagomorpha  
 
58
rabbit, hare, pika
 
 
  Pinnipedia  
 
33
seal, walrus
 
 
  Edentata  
 
29
anteater, armadillo, sloth
 
 
  Perissodactyla  
 
16
horse, rhinoceros, tapir
 
 
  Hyracoidea  
 
11
hyrax
 
 
  Pholidota  
 
7
pangolin
 
 
  Sirenia  
 
4
dugong, manatee
 
 
  Dermoptera  
 
2
flying lemur
 
 
  Proboscidea  
 
2
elephant
 
 
  Tubulidentata  
 
1
aardvark


 

   
 
  species as to how long the young remain inside the mother, with larger species tending to have longer gestation periods than smaller species. Placental mammals are found worldwide.  
 
   
 
  marsupials  
 
   
 
  Marsupials are mammalian species in which the young are born at an early stage of development and develop further in a pouch on the mother's body where they  
 
Mammals: Average Gestation Times
Mammal Gestation (days) Mammal Gestation (days)
Ass 365 Lion 108
Baboon 187 Llama 330
Bear (black) 210 Mink 40–75
Bear (grizzly) 225 Monkey (rhesus) 164
Bear (polar) 60 Moose 240–250
Beaver 122 Mouse (domestic white) 19
Buffalo (American) 270 Mouse (meadow) 21
Camel (Bactrian) ~410 Muskrat 28–30
Cat (domestic) 58–65 Opossum (American) 12–13
Chimpanzee 23 Oryx 260–5
Chinchilla 110–120 Otter 270–300
Chipmunk 31 Pig (domestic) 112–115
Cow 279–292 Porcupine 112
Deer (white-tailed) 201 Puma 90
Dog (domestic) 58–70 Rabbit (domestic) 30–35
Elephant (Asian) 645 Raccoon 63
Elk (Wapiti) 240–250 Rhinoceros (black) 450
Fox (red) 52 Seal 330
Giraffe 420–450 Sea lion (California) 350
Goat (domestic) 145–155 Sheep (domestic) 144–151
Gorilla 257 Squirrel (gray) 30–40
Guinea pig 68 Tiger 105–113
Hippopotamus 225–250 Whale (sperm) 480–500
Horse 330–342 Wolf 60–68
Kangaroo 42 Zebra (Grant's) 365
Leopard 92–95    


 

 

 

 

   
Page 389
   
 
  are attached to and fed from a nipple. They occupy many specialized niches in South America and, especially, Australasia.  
 
   
 
  Marsupials include the kangaroo, wombat, opossum, phalanger, bandicoot, dasyure, and wallaby. The Australian marsupial anteater known as the numbat is unusual in that it has no pouch.  
 
 
  Marsupial Cooperative Research Centre
http://www.newcastle.edu.au/department/bi/birjt/jrcrc/
 
 
 
  Interesting details of latest research into marsupial preservation issues in Australasia. It examines efforts to preserve endangered species, whilst scientifically culling those in excess numbers and restricting introduced predators. For further information there is a link to Australia's Genome Research Network.  
 
   
 
  monotremes  
 
   
 
  Monotremes are mammals that lay eggs. The young are then nourished with milk. There are only a few types surviving (platypus and two kinds of echidna).  
 
 
  Remarkable Platypus
http://www.anca.gov.au/plants/manageme/platintr.htm
 
 
 
  Comprehensive information on the shy monotreme presented by the Australian Natural Conservation Agency. Findings of latest research into platypuses is presented, together with recommendations to help preserve the species.  
 
   
 
  0389-01.jpg  
 
   
 
  echidna The short-nosed echidna is found
throughout Australia. Echidnas are egg-
laying mammals (monotremes). They are
nocturnal and live almost exclusively
on ants and termites.
 
 
   
 
  Birds  
 
   
 
  Birds make up the class Aves, the biggest group of land vertebrates. They are characterized by warm blood  
 
Classification of Major Bird Groups
Order Example
Tinamiformes tinamous
Rheiformes rhea
Struthioniformes ostrich
Casuarüformes cassowary, emu
Apterygiformes moas, kiwi
Podicipediformes grebe
Dinornithiformes moa
Procellariformes albatross, petrel, shearwater, storm petrel
Sphenisciformes penguin
Pelecaniformes pelican, booby, gannet, frigate bird
Anseriformes duck, goose, swan
Phoenicopteriformes flamingo
Ciconüformes heron, ibis, stork, spoonbill
Falconiformes falcon, hawk, eagle, buzzard, vulture
Galliformes grouse, partridge, pheasant, turkey
Gruiformes crane, rail, bustard, coot
Charadrüformes wader, gull, auk, oyster-catcher, plover, puffin, tern
Gavüformes diver
Columbiformes dove, pigeon, sandgrouse
Psittaciformes parrot, macaw, parakeet
Cuculiformes cuckoo, roadrunner
Strigiformes owl
Caprimulgiformes nightjar, oilbird
Apodiformes swift, hummingbird
Colüformes mousebird
Trogoniformes trogon
Coracüformes kingfisher, hoopoe
Piciformes woodpecker, toucan, puffbird
Passeriformes finch, crow, warbler, sparrow, weaver, jay, lark, blackbird, swallow, mockingbird, wren, thrush


 

   
 
  (usually about 41°C/106°F, higher than that of mammals), feathers, wings, breathing through lungs, and egg-laying by the female. Birds are bipedal (they have two feet); feet are usually adapted for perching and never have more than four toes. Hearing and eyesight are well developed, but the sense of smell is usually poor. No existing species of bird possesses teeth.  
 
bird: names
   
 
  Rifleman, short-tailed pygmy tyrant, frilled coquette, bobwhite, tawny frogmouth, trembler, wattle-eye, fuscous honeyeater, dickcissel, common grackle, and forktailed drongo are all common names for species of bird.  
 


 

   
 
  Most birds fly, but some groups (such as ostriches) are flightless, and others include flightless members. Many communicate by sounds  
 

 

 

 

   
Page 390
   
 
  0390-01.gif  
 
   
 
  wing Birds can fly because of the specialized shape of their wings: a
rounded leading edge, flattened underneath and round on top. This
airfoil shape produces lift in the same way that an aircraft wing does.
The outline of the wing is related to the speed of flight. Fast birds of
prey have a streamlined shape. Larger birds, such as the eagle, have
large wings with separated tip feathers which reduce drag and allow
slow flight. Insect wings are not aerofoils. They push downward to
produce lift  in the same way that oars are used to push through water.
 
 
 
  Royal Society for the Protection of Birds
http://birdcare.com/bin/showpage/birdaction/rspb
 
 
 
  Home page of the RSPB. The website includes a vast amount of information on birds and bird watching in the UK, with descriptions, sketches and photographs of every common UK bird. The site also holds information on how to join the society, and lists the society's sites and activities around the country.  
 
   
 
  (nearly half of all known species are songbirds) or by visual displays, in connection with which many species are brightly colored, usually the males. Birds have highly developed patterns of instinctive behavior. There are nearly 8,500 species of birds. The study of birds is called ornithology.  
 
   
 
  According to the Red List of endangered species published by the World Conservation Union (IUCN) for 1996, 11% of bird species are threatened with extinction.  
 
 
  Bird On!
http://birdcare.com/birdon/welcome_text.html
 
 
 
  News and features on the whats and whereabouts of wild birds in Britain and Europe. The site is run by two self-confessed bird enthusiasts and includes information on caring for birds, as well as an extensive library of pictures and photographs.  
 
   
 
  0390-02.jpg  
 
   
 
  feather Types of feather. A bird's wing is made up of two types of feather:
contour feathers and flight feathers. The primary and secondary feathers are
flight feathers. The coverts are contour feathers, used to streamline the bird.
Semiplume and down feathers insulate the bird's body and provide color.
 
 

 

 

 

   
Page 391
Classification of Dinosaurs
Order Suborder Description and examples
Subclass Archosauria Superorder Dinosauria  
Saurischia Theropoda Bipedal, "beast-footed" carnivores: Tyrannosaurus rex, Dilophosaurus, Velociraptor, Deinonychus
Sauropodomorpha   Quadripedal, sometimes gigantic herbivores: Apatosaurus, Brachiosaurus, Diplodocus
Ornithischia Ornithopoda Mostly bipedal, sometimes duck-billed herbivores: Hadrosaurus, Heterodontosaurus, Iguanodon
  Thyreophora (Enoplosauria) armored herbivores: Stegosaurus, Ankylosaurus
horned or "bone-headed" herbivores: Triceratops, Psittacosaurus
  Marginocephalia


 

   
 
  Reptiles  
 
   
 
  Reptiles are vertebrates belonging to the class Reptilia. Unlike amphibians (see below), reptiles have hard-shelled, yolk-filled eggs that are laid on land and from which fully formed young are born. Some snakes and lizards retain their eggs and give birth to live young. Reptiles are cold-blooded, and their skin is usually covered with scales. The metabolism is slow, and in some cases (certain large snakes) intervals between meals may be months. Reptiles date back over 300 million years.  
 
   
 
  Many extinct forms are known, including the orders Pterosauria, Plesiosauria, Ichthyosauria, and the dinosaur order Saurischia and Ornithschia. The chief living reptile orders are the Testudines or Chelonia (tortoises and turtles), Crocodilia (alligators and crocodiles), and Squamata, divided into three suborders: Sauria or Lacertilia (lizards), Ophidia or Serpentes (snakes), and Amphisbaenia (worm lizards). The order Rhynchocephalia has one surviving genus with two species, the lizardlike tuataras of New Zealand.  
 
   
 
  0391-01.jpg  
 
   
 
  crocodile The estuarine or saltwater crocodile, of India,
southeast Asia, and Australasia, is one of the largest
and most dangerous of its family. It has been known
to develop a taste for human flesh. Hunted near
to extinction for its leather, it is now protected by
restrictions and the trade in skins is controlled.
 
 
Classification of Living Reptiles
 
 
  Order  
 
Suborder Number of species Examples
Subclass Anapsida      
 
 
  Testudines (Chelonia)  
 
Cryptodira 220 turtle, tortoise, terrapin
  Pleurodira 70 sideneck turtle
Subclass Lepidosauria      
  Rhynchocephalia 2 tuatara
 
 
  Squamata  
 
Sauria (Lacertilia) 4,500 lizards: iguana, gecko, gila monster, skink
  Ophidia (Serpentes) 3,000 snakes: python, viper, cobra, sea snake
  Amphisbaenia 160 worm lizard
Subclass Archosauria      
  Crocodilia 23 crocodile, alligator, gavial, cayman


 

 

 

 

   
Page 392
   
 
  Amphibians  
 
   
 
  Amphibians belong to the vertebrate class Amphibia (from Greek, meaning ''double life"), which generally spend their larval (tadpole) stage in fresh water, transferring to land at maturity (after metamorphosis) and generally returning to water to breed. Like fish and reptiles, they continue to grow throughout life, and cannot maintain a temperature greatly differing from that of their environment. The class contains 4,553 known species, 4,000 of which are frogs and toads, 390 salamanders, and 163 caecilians (wormlike in appearance).  
 
   
 
  frog: new species  
 
   
 
  A newly discovered frog species is so tiny that it can sit comfortably on a human fingernail. The frog, Psyllophryne didactyla, was discovered in Cuba in 1996.  
 


 

   
 
  0392-01.jpg  
 
   
 
  axolotl The rare axolotl Ambystoma mexicanum lives in mountain lakes in Mexico.
The capture of specimens as pets and the introduction of predatory fish has led to
a decline in numbers. Axolotls spend most of their lives in water in a larval state,
breathing by means of three pairs of feathery gills and having undeveloped legs
and feet. Occasionally, individuals may develop into the adult, land-living form.
 
 
   
 
  Fish  
 
   
 
  Fish are aquatic vertebrates that use gills to obtain oxygen from fresh or sea water. There are three main groups: the bony fishes or Osteichthyes (goldfish, cod, tuna, etc.); the cartilaginous fishes or Chondrichthyes (sharks, rays, etc.); and the jawless fishes or Agnatha (hagfishes, lampreys, etc.). The majority of fishes are predators, feeding on other fishes and invertebrates.  
 
   
 
  Fishes of some form are found in virtually every body of water in the world except for the very salty water of the Dead Sea and some of the hot larval springs. Of the 30,000 fish species, approximately 2,500 are freshwater.  
 
   
 
  mudskipper  
 
   
 
  There is a fish that can climb trees. The mudskipper spends three-quarters of its time out of water. Malaysian mudskippers live in mangrove swamps, where they climb among the tangled stems and roots, and sometimes into the branches.  
 


 

   
 
  The world's largest fish is the whale shark Rhineodon typus, more than 20 m/66 ft long; the smallest is the dwarf pygmy goby Pandaka pygmae), 7.5–9.9 mm/0.3–0.4 in long. The study of fishes is called ichthyology.  
 
   
 
  Bony Fishes  
 
   
 
  These constitute the majority of living fishes (about 20,000 species). The skeleton is bone, movement is controlled by mobile fins, and the body is usually covered with scales. The gills are covered by a single flap. Many have a swim bladder with which the fish adjusts its buoyancy. Most lay eggs, but some fishes are internally fertilized and retain eggs until hatched inside the body, then giving birth to live young. Most bony fishes are ray-finned fishes, but a few, including lungfishes and coelacanths, are fleshy-finned.  
 
fish: names
   
 
  Spurdog, alewife, twaite shad, jollytail, tadpole madtom, bummalow, walleye pollock, wrestling halfbeak, mummichog, jolthead porgy, sweetlip emperor, and slippery dick are all common names for species of fish.  
 


 

Classification of Living Amphibians
Order Number of species Examples
Anura (Salientia) 4,000 frog, toad
Urodela (Caudata) 390 salamander, newt, axolotl, mudpuppy
Apoda (Gymnophiona) 163 caecilian


 

 

 

 

   
Page 393
Classification of Fish
 
 
  Order  
 
Number of species Examples
Superclass Agnatha (jawless fishes)    
 
 
  Class Cyclostomota (scaleless fish with round mouths)  
 
 
 
 
  Petromyzoniformes  
 
 
 
  30  
 
lamprey
 
 
  Myxiniformes  
 
 
 
  15  
 
hagfish
 
 
  Subphylum: Gnathostomata (jawed vertebrates)  
 
   
Superclass Pisces    
 
 
  Class Chondrichthyes (cartilaginous fishes)  
 
   
 
 
  Subclass Elasmobranchü (sharks and rays)  
 
   
 
 
  Hexanchiformes  
 
 
 
  6  
 
frilled shark, comb-toothed shark
 
 
  Heterodontiformes  
 
 
 
  10  
 
Port Jackson shark
 
 
  Lamniformes  
 
 
 
  200  
 
"typical" shark
 
 
  Rajiformes  
 
 
 
  300  
 
skate, ray
 
 
  Subclass Holocephali (rabbitfishes)  
 
   
 
 
  Chimaeriformes  
 
 
 
  20  
 
chimaera, rabbitfish
Class Osteichthyes (bony fishes)    
 
 
  Subclass Sarcopterygü (lobe-finned fishes)  
 
   
 
 
  Coelacanthiformes  
 
 
 
  1  
 
coelacanth
 
 
  Ceratodiformes  
 
 
 
  1  
 
Australian lungfish
 
 
  Lepidosireniformes  
 
 
 
  4  
 
South American and African lungfish
 
 
  Subclass Actinopterygü (ray-finned fishes)  
 
   
 
 
  Polypteriformes  
 
 
 
  11  
 
bichir, reedfish
 
 
  Acipensiformes  
 
 
 
  25  
 
paddlefish, sturgeon
 
 
  Amüformes  
 
 
 
  8  
 
bowfin, garpike
Superorder Teleostei    
 
 
  Elopiformes  
 
 
 
  12  
 
tarpon, tenpounder
 
 
  Anguilliformes  
 
 
 
  300  
 
eel
 
 
  Notacanthiformes  
 
 
 
  20  
 
spiny eel
 
 
  Clupeiformes  
 
 
 
  350  
 
herring, anchovy
 
 
  Osteoglossiformes  
 
 
 
  16  
 
arapaima, African butterfly fish
 
 
  Mormyriformes  
 
 
 
  150  
 
elephant-trunk fish, featherback
 
 
  Salmoniformes  
 
 
 
  500  
 
salmon, trout, smelt, pike
 
 
  Gonorhynchiformes  
 
 
 
  15  
 
milkfish
 
 
  Cypriniformes  
 
 
 
  350  
 
carp, barb, characin, loache
 
 
  Siluriformes  
 
 
 
  200  
 
catfish
 
 
  Myctophiformes  
 
 
 
  300  
 
deep-sea lantern fish, Bombay duck
 
 
  Percopsiformes  
 
 
 
  10  
 
pirate perch, cave-dwelling amblyopsid
 
 
  Batrachoidiformes  
 
 
 
  10  
 
toadfish
 
 
  Gobiesociformes  
 
 
 
  100  
 
clingfish, dragonets
 
 
  Lophüformes  
 
 
 
  150  
 
anglerfish
 
 
  Gadiformes  
 
 
 
  450  
 
cod, pollack, pearlfish, eelpout
 
 
  Atheriniformes  
 
 
 
  600  
 
flying fish, toothcarp, halfbeak
 
 
  Lampridiformes  
 
 
 
  50  
 
opah, ribbonfish
 
 
  Beryciformes  
 
 
 
  150  
 
squirrelfish
 
 
  Zeiformes  
 
 
 
  60  
 
John Dory, boarfish
 
 
  Gasterosteiformes  
 
 
 
  150  
 
stickleback, pipefish, seahorse
 
 
  Channiformes  
 
 
 
  5  
 
snakeshead
 
 
  Synbranchiformes  
 
 
 
  7  
 
cuchia
 
 
  Scorpaeniformes  
 
 
 
  700  
 
gurnard, miller's thumb, stonefish
 
 
  Dactylopteriformes  
 
 
 
  6  
 
flying gurnard
 
 
  Pegasiformes  
 
 
 
  4  
 
sea-moth
 
 
  Pleuronectiformes  
 
 
 
  500  
 
flatfish
 
 
  Tetraodontiformes  
 
 
 
  250  
 
puffer fish, triggerfish, sunfish
 
 
  Perciformes  
 
 
 
  6,500  
 
perch, cichlid, damsel fish, gobie, wrass, parrotfish, gourami, marlin, mackerel, tuna, swordfish, spiny eel, mullet, barracuda, sea bream, croaker, ice fish, butterfish


 

 

 

 

   
Page 394
   
 
  0394-01.jpg  
 
   
 
  fish anatomy The anatomy of a fish. All fishes move through water using
their fins for propulsion. The bony fishes, like the specimen shown here,
constitute the largest group of fishes with about 20,000 species.
 
 
   
 
  Cartilaginous Fishes  
 
   
 
  These have skeletons made of cartilage, with the mouth generally beneath the head, a large and sensitive nose, and a series of open gill slits along the neck region; they are efficient hunters. Cartilaginous fishes have no swimbladder and, in order to remain buoyant, must keep swimming. They may lay eggs ("mermaid's purses") or bear live young. Some types, such as sharks, retain the shape they had millions of years ago. There are fewer than 600 known species of sharks and rays.  
 
shark
   
 
  A basking shark can sieve more than 1,000 metric tons/1,102 U.S. tons of water an hour in search of food.  
 


 

   
 
  0394-02.jpg  
 
   
 
  hammerhead shark The hammerhead shark's name derives
from the flattened projections at the side of its head. The eyes
are on the outer edges of the projections. The advantages
of this head design are not known; it may be hat the shark's
vision is improved by the wide separation of the eyes,
or the head may provide extra lift by acting as an airfoil.
 
 
 
  Shark
http://www.seaworld.org/animal_bytes/sharkab.html
 
 
 
  Illustrated guide to the shark including information about genus, size, life span, habitat, gestation, diet, and a series of fun facts.  
 
   
 
  jawless fishes  
 
   
 
  Jawless fishes have a body plan like that of some of the earliest vertebrates that existed before true fishes with jaws evolved. There is no true backbone but a notochord. The lamprey attaches itself to the fishes on which it feeds by a suckerlike rasping mouth. Hagfishes are entirely marine, very slimy, and feed on carrion and injured fishes.  
 
 
  Ichthyology Resources
http://muse.bio.cornell.edu/cgi-bin/hl?fish
 
 
 
  Everything anyone should need for studying fish, including historical information about development, as well as up-to-date listings of currently endangered species.  
 
   
 
  Other Major Phyla  
 
   
 
  The mammals, birds, reptiles, amphibians, and fishes all belong to the phylum Chordata.  
 

 

 

 

   
Page 395
Classification of Mollusks
phylum Mollusca  
class Monoplacophora primitive marine forms, including Neopilina (2 species)
class Amphineura wormlike marine forms
 
 
  1 Aplacophora  
 
chitons, coat-of-mail
 
 
  2 Polyplacophora  
 
shells (1,150 species)
class Gastropoda snail-like mollusks, with single or no shell (9,000 species)
 
 
  1 Prosobranchia  
 
limpets, winkles, whelks
 
 
  2 Opisthobranchia  
 
seaslugs, land and sea snails
 
 
  3 Pulmonata  
 
freshwater snails, slugs
class Scaphopoda tusk shells, marine burrowers (350 species)
class Bivalvia mollusks with a double (two-valved) shell (15,000 species): mussels, oysters, clams, cockles, scallops, tellins, razor shells, shipworms
class Cephalopoda mollusks with shell generally reduced, arms to capture prey, and beaklike mouth; body bilaterally symmetrical and nervous system well developed (750 species): squids, cuttlefish, octopuses, pearly nautilus, argonaut


 

   
 
  Animals belonging to some of the other major phyla are described below.  
 
   
 
  echinoderms  
 
   
 
  Echinoderms are marine invertebrates of the phylum Echinodermata ("spiny-skinned"), characterized by a five-radial symmetry. Echinoderms have a water-vascular system which transports substances around the body. They include starfishes (or sea stars), brittlestars, sea lilies, sea urchins, and sea cucumbers. The skeleton is external, made of a series of limy plates. Echinoderms generally move by using tube-feet, small water-filled sacs that can be protruded or pulled back to the body.  
 
   
 
  mollusks  
 
   
 
  Mollusks belong to the phylum Mollusca. They comprise a group of invertebrate animals, most of which have a body divided into three parts: a head, a central mass containing the main organs, and a foot for movement; the more sophisticated octopuses and related mollusks have arms to capture their prey. Mollusks have  
 
mollusk
   
 
  The chiton, a species of marine shelled mollusk, uses magnetism to find its way home. The teeth on its tongue-like radula contain magnetite, and enable the chiton to return to exactly the same place on its home rock after night-time feeding.  
 


 

   
 
  0395-01.jpg  
 
   
 
  giant clam Giant clam Tridacna gigus at Lady Elliott Island, in the Great
Barrier Reef, Australia. It obtains its nutrition by a symbiotic association
with photosynthetic algae.Giant clams are the largest living bivalves,
growing to lengths of around 1 m/ 39 in. Chris McTernan
 
 

 

 

 

   
Page 396
   
 
  varying diets, the carnivorous species feeding mainly on other mollusks. Some are vegetarian. The majority of mollusks are marine animals, but some live in fresh water, and a few live on dry land. They include clams, mussels, and oysters (bivalves), snails and slugs (gastropods), and cuttlefish, squids, and octopuses (cephalopods). The body is soft, without limbs (except for the cephalopods), and cold-blooded. There is no internal skeleton, but many species have a hard shell covering the body.  
 
   
 
  arthropods  
 
   
 
  Arthropods belong to the phylum Arthropoda; they are invertebrate animals with jointed legs and a segmented body with a horny or chitinous casing (exoskeleton), which is shed periodically and replaced as the animal grows. The phylum includes arachnids such as spiders and mites, as well as crustaceans, myriapods such as millipedes and centipedes, and insects.  
 
   
 
  arachnids An arachnid, or arachnoid, is an arthropod of the class Arachnida, which includes spiders, scorpions, ticks, and mites. They differ from insects in possessing only two main body regions, the cephalothorax and the abdomen, and in having eight legs.  
 
 
  Arachnology
http://dns.ufsia.ac.be/Arachnology/Arachnology.html
 
 
 
  Largely a collection of annotated links, organized under headings such as taxonomy and classification, paleontology, poison, bites, diseases, pests, and phobia. The site also contains spider-related myths, stories, poems, songs, and art.  
 
   
 
  crustaceans  
 
   
 
  A crustacean is one of the class of arthropods that includes crabs, lobsters, shrimps, woodlice, and barnacles. The external skeleton is made of protein and chitin hardened with lime. Each segment bears a pair of appendages that may be modified as sensory feelers (antennae), as mouthparts, or as swimming, walking, or grasping structures.  
 
   
 
  myriapods  
 
   
 
  A myriapod is a terrestrial arthropod characterized by a long, segmented body and many legs. Centipedes and millipedes are the most familiar myriapods. The bodies of centipedes are composed of up to almost 200 segments,  
 
termite
   
 
  Termite nests may house two million termites and reach heights of up to 6 m/6.6 yd. A skyscraper built to the same scale would be 8 km/5 mi high.  
 


 

   
 
  0396-01.jpg  
 
   
 
  insect, body plan Body plan of an insect. The general features of the
insect body include a segmented body divided into head, thorax, and
abdomen, jointed legs, feelers or antennae, and usually two pairs of
wings. Insects often have compound eyes with a large field of vision.
 
 

 

 

 

   
Page 397
Classification of Insects
(N/A = not available.)    
 
 
  Order  
 
Number
of species
Examples
Apterygota (wingless insects)    
 
 
  Thysanura  
 
 
 
  350  
 
three-pronged bristletails, silverfish
 
 
  Diplura  
 
 
 
  400  
 
two-pronged bristletails, campodeids, japygids
 
 
  Protura  
 
 
 
  50  
 
minute insects living in soil
 
 
  Collembola1  
 
 
 
  1,500  
 
springtails
Pterygota (winged insects or forms secondary wingless)  
 
 
  Exopterygota (young resemble adults but have externally-developing wings)  
 
   
 
 
  Ephemeroptera  
 
 
 
  1,000  
 
mayflies
 
 
  Odonata  
 
 
 
  5,000  
 
dragonflies, damselflies
 
 
  Plecoptera  
 
 
 
  3,000  
 
stoneflies
 
 
  Grylloblattodea  
 
 
 
  12  
 
wingless soil-living insects of North America
 
 
  Orthoptera  
 
 
 
  20,000  
 
crickets, grasshoppers, locusts, mantids, roaches
 
 
  Phasmida  
 
 
 
  2,000  
 
stick insects, leaf insects
 
 
  Dermaptera  
 
 
 
  1,000  
 
earwigs
 
 
  Embioptera  
 
 
 
  150  
 
web-spinners
 
 
  Dictyoptera  
 
 
 
  5,000  
 
cockroaches, praying mantises
 
 
  Isoptera  
 
 
 
  2,000  
 
termites
 
 
  Zoraptera  
 
 
 
  16  
 
tiny insects living in decaying plants
 
 
  Psocoptera  
 
 
 
  1,600  
 
booklice, barklice, psocids
 
 
  Mallophaga  
 
 
 
  2,500  
 
biting lice, mainly parasitic on birds
 
 
  Anoplura  
 
 
 
  250  
 
sucking lice, mainly parasitic on mammals
 
 
  Hemiptera  
 
 
 
  55,000  
 
true bugs, including shield- and bedbugs, froghoppers, pond skaters, water boatmen
 
 
  Homoptera  
 
 
 
  N/A  
 
aphids, cicadas
 
 
  Thysanoptera  
 
 
 
  5,000  
 
thrips
Endopterygota (young unlike adults, undergo sudden metamorphosis)
 
 
  Neuroptera  
 
 
 
  4,500  
 
lacewings, alder flies, snake flies, ant lions
 
 
  Mecoptera  
 
 
 
  300  
 
scorpion flies
 
 
  Lepidoptera  
 
 
 
  165,000  
 
butterflies, moths
 
 
  Trichoptera  
 
 
 
  3,000  
 
caddis flies
 
 
  Diptera  
 
 
 
  80,000  
 
true flies, including bluebottles, mosquitoes, leatherjackets, midges
 
 
  Siphonaptera  
 
 
 
  1,400  
 
fleas
 
 
  Hymenoptera  
 
 
 
  100,000  
 
bees, wasps, ants, sawflies, chalcids
 
 
  Coleoptera  
 
 
 
  350,000  
 
beetles, including weevils, ladybugs, glowworms, woodworms, chafers
1 Some zoologists recognize the Collembola taxon as a class rather than an order.


 

   
 
  each of similar form and bearing a single pair of legs. Millipedes have fewer body segments (up to 100) but have two pairs of legs on each.  
 
   
 
  insects  
 
   
 
  The insects form a vast group of small invertebrate animals with hard, segmented bodies, three pairs of jointed legs, and, usually, two pairs of wings; they are distributed throughout the world. An insect's body is divided into three segments: head, thorax, and abdomen. On the head is a pair of  
 
   
 
  housefly  
 
   
 
  In nine months, a housefly could lay enough eggs to produce a layer of flies that would cover all of Germany to a depth of 14 m/47 ft.  
 


 

 

 

 

   
Page 398
   
 
  feelers, or antennae. The legs and wings are attached to the thorax, or middle segment of the body. The abdomen, or end segment of the body, is where food is digested and excreted and where the reproductive organs are located.  
 
   
 
  Insects vary in size from 0.02 cm/0.007 in to 35 cm/13.5 in in length. The world's smallest insect is believed to be a "fairy fly" wasp in the family Mymaridae, with a wingspan of 0.2 mm/ 0.008 in. locust  
 
locust
   
 
  Locust swarms can contain up to 10 billion individuals and cover a surface of 1,000 sq km/400 sq mi. The swarm can remain together for weeks, devastating crops and other vegetation for thousands of miles. Each square kilometer (0.4 square miles) of locusts (up to 80 million individuals) can consume 250 metric tons of food a day, the daily amount required to feed 80,000 people.  
 


 

   
 
  annelids  
 
   
 
  Annelids are segmented worms belonging to the phylum Annelida. Annelids include earthworms, leeches, and marine worms such as lugworms. They have a distinct head and soft body, which is divided into a number of similar segments shut off from one another internally by membranous partitions, but there are no jointed appendages. Annelids are noted for their ability to regenerate missing parts of their bodies.  
 
   
 
  0398-01.jpg  
 
   
 
  annelid Annelids are worms with segmented bodies.
The ragworm, lugworm, and peacock worm shown
here are all marine species. Ragworms commonly
live in mucouslined burrows on muddy shores or
under stones, and lugworms occupy U-shaped
burrows. The peacock worm, however, builds a
smooth, round tube from fine particles of mud.
 
 
   
 
  nematodes  
 
   
 
  Nematodes are unsegmented worms belonging to the phylum Nematoda. They are pointed at both ends, with a tough, smooth outer skin. They include many free-living species found in soil and water, including the sea, but a large number are parasites, such as the roundworms and pinworms that live in humans, or the eelworms that attack plant roots. They differ from flatworms (the platyhelminths, see below) in that they have two openings to the gut (a mouth and an anus).  
 
   
 
  Most nematode species are found in deep-sea sediment. Around 13,000 species are known, but a 1995 study by the Natural History Museum, London, England, based on the analysis of sediment from 17 seabed sites worldwide, estimated that nematodes may make up as much as 75% of all species, with there being an estimated 100 million species. Some are anhydrobiotic, which means they can survive becoming dehydrated, entering a state of suspended animation until they are rehydrated.  
 
   
 
  nematode  
 
   
 
  The nematode Placentonema gigantissima lives as a parasite in the placenta of sperm whales. It can reach 8 m/26 ft in length and 2.5 cm/1 in in diameter.  
 


 

   
 
  platyhelminths  
 
   
 
  Platyhelminths are flatworms belonging to the phylum Platyhelminthes. Some are free-living, but many are parasitic (for example, tapeworms and flukes). The body is simple and bilaterally symmetrical, with one opening to the intestine. Many are hermaphroditic (with both male and female sex organs) and practice self-fertilization.  
 
   
 
  coelenterates  
 
   
 
  Coelenterates are freshwater or marine organisms belonging to the phylum Coelenterata. They have a body wall composed of two layers of cells. They also possess stinging cells. Examples are jellyfish, hydra, sea anemones, and coral.  
 

 

 

 

   
Page 399
   
 
  0399-01.jpg  
 
   
 
  coral Corals are marine animals related to jellyfishes
and sea anemones. Most hard or stony corals live as
colonies of polyps that secrete a rigid external skeleton
of lime. But there are also those that live as solitary
individuals. Corals grow in a wide variety of forms
as the types here demonstrate. Sea fans, for example,
have an internal skeleton linking the polyps, while the
polyps of the brain coral are arranged in rows. The
stagshorn coral gets its name from the resemblance
of the colony to a male deer's antlers. The names of
the plate and pillar corals also reflect their appearance.
 
 
   
 
  sponges  
 
   
 
  Sponges are saclike simple invertebrates belonging to the phylum Porifera, usually marine. A sponge has a hollow body, its cavity lined by cells bearing flagella, whose whiplike movements keep water circulating, bringing in a stream of food particles. The body walls are strengthened with protein (as in the bath sponge) or small spikes of silica, or a framework of calcium carbonate.  
 
   
 
  Feeding  
 
   
 
  As well as being divided up taxonomically, animals are also loosely categorized by what they eat. They can be divided into three feeding types: herbivores eat plants and plant products, carnivores eat other animals, and omnivores eat both. Since few animals can digest cellulose, herbivores have either symbiotic cellulose-digesting bacteria or protozoa in their guts, or grinding mechanisms, such as the large flattened teeth of elephants, to release the plant protoplasm from its  
 
   
 
  0399-02.jpg  
 
   
 
  dentition The dentition and dental formulae
of a typical herbivore (sheep) and carnivore
(dog). The dog has long pointed canines for
puncturing and gripping its prey and has
modified premolars and molars (carnassials)
for shearing flesh. In the sheep, by contrast,
there is a wide gap, or diastema, between
the incisors, developed for cutting through
blades of grass, and the grinding premolars
and molars; the canines are absent.
 
 

 

 

 

   
Page 400
   
 
  cellulose-walled cells. Carnivores are adapted for hunting and eating flesh, with well-developed sense organs and fast reflexes, and weapons such as sharp fangs, claws, and stings. Omnivores eat whatever they can find, and often scavenge among the remains of carnivores' prey; because of the diversity of their diet, they have more versatile teeth and guts than herbivores or carnivores. Many animals are adapted for a parasitic way of life, living on other animals or plants, and feeding solely by absorbing fluids from their hosts. Some animals absorb food directly into their body cells; others have a digestive system in which food is prepared for absorption by body tissues.  
 
   
 
  Life Cycles  
 
   
 
  All animals go through a sequence of developmental stages, according to their species. Most vertebrate life cycles are relatively simple, consisting of fertilization of sex cells or gametes, a period of development as an embryo, a period of juvenile growth after hatching or birth, an adulthood including sexual reproduction, and finally death.  
 
   
 
  Invertebrate life cycles are generally more complex and may involve major reconstitution of the individual's appearance (metamorphosis) and completely different styles of life. Many insects such as cicadas, dragonflies, and mayflies have a long larval or pupal phase and a short adult phase. Dragonflies live an aquatic life as larvae and an aerial life during the adult phase. In many invertebrates there is a sequence of stages in the life cycle, and in parasites different stages often occur in different host organisms.  
 
   
 
  reproduction  
 
   
 
  sexual reproduction Most vertebrate animals reproduce sexually, in a process that requires the union, or fertilization of gametes (eggs and sperm in higher organisms). These are usually produced by two different individuals, a male who produces sperm and a female who produces eggs. Many animals go through some form of courtship before mating. In mammals, birds, reptiles, and terrestrial insects, fertilization occurs internally, within the body of the female; the male introduces sperm into the reproductive tract of the female through a penis or other organ, while most birds transfer sperm by pressing their cloacas (the opening of their reproductive tracts) together. In the majority of amphibians and fishes, and most aquatic invertebrates, fertilization occurs externally, when the female lays her eggs in the water and the male releases sperm onto them. The successful fusion of a male and female gamete produces a zygote, from which a new individual develops. The embryo develops within an egg, where it is nourished by food contained in the yolk, or in mammals in the uterus of the mother. In mammals (except marsupials and monotremes) the embryo is fed through the placenta. After birth or hatching, the parents often continue to care for and feed their young until they are able to survive independently.  
 
monogamy
   
 
  Less than 3% of mammals are monogamous.  
 


 

sea horse
   
 
  In sea horses it is the male that carries the babies. The female deposits her eggs into his brood pouch, where he fertilizes them. They remain there for up to six weeks while he nourishes them till they reach independence.  
 


 

   
 
  other forms of reproduction Other forms of nonsexual reproduction found in the animal kingdom are parthenogenesis and self-fertilization. Parthenogenesis is the development of an ovum (egg) without any genetic contribution from a male. It is the normal means of reproduction of some fishes. Some sexually reproducing species, such as aphids, show parthenogenesis at some stage in their lite cycle to accelerate reproduction to take advantage of good conditions. Selffertilization occurs in a few hermaphrodites (organisms having both male and female sex organs), such as tapeworms. Hermaphroditism is the norm in such species as earthworms and snails, but cross-fertilization is generally the rule among hermaphrodites, with the parents functioning  
 
velvet worm
   
 
  The mating technique of African velvet worms is bizarre. The male places sperm bundles anywhere along the female's body. Beneath the sperm bundle the skin dissolves forming a hole. The sperm can thus enter the female's body cavity, where it makes its way to her ovaries.  
 


 

 

 

 

   
Page 401
   
 
  0401-01.jpg  
 
   
 
  egg Section through a fertilized bird egg. Inside
a bird's egg is a complex structure of liquids and
membranes designed to meet the needs of the
growing embryo. The yolk, which is rich in fat,
is gradually absorbed by the embryo. The white
of the egg provides protein and water. The chalaza
is a twisted band of protein which holds the yolk
in place and acts as a shock absorber. The airspace
allows gases to be exchanged through the shell.
The allantois contains many blood vessels which
carry gases between the embryo and the outside.
 
 
   
 
  as male and female simultaneously, or as one or the other sex at different stages in their development. Fragmentation occurs in some invertebrates, such as jellyfish: parts of the organisms break away and subsequently differentiate to form new organisms. Regeneration may sometimes occur before separation, producing chains of offspring budding from the parent organism.  
 
   
 
  amphibian metamorphosis  
 
   
 
  Most amphibian species go through an aquatic larval stage as tadpoles, undergoing metamorphosis in the water to emerge as adults that move onto land. In the typical life cycle of a frog, eggs are laid in large masses (spawn) in fresh water. The tadpoles hatch from the eggs in about a fortnight. At first they are fishlike animals with external gills and a long swimming tail, but no limbs. The first change to take place is the disappearance of the external gills and the development of internal gills which are still later supplanted by lungs. The hind legs appear before the front legs, and the last change to occur is the diminution and final disappearance of the tail. The tadpole  
 
   
 
  0401-02.jpg  
 
   
 
  aphid During spring and summer female aphids such as this Macrosiphum
cholodkovskyi 
produce a continuous succession of offspring by parthenogenesis,
but mate and lay eggs before the onset of winter. Premaphotos Wildlife
 
 

 

 

 

   
Page 402
   
 
  0402-01.jpg  
 
   
 
  braconid wasp The larvae of many parasitic wasps develop inside the bodies of
other insects. These larvae of the braconid wasp Apanteles glomeratus are boring
their way out through the skin of their host, a caterpillar of the large white butterfly
Pieris brassicae, in order to pupate. Parasites such as these, which normally kill
their host, are sometimes distinguished from ''true" parasites. Premaphotos Wildlife
 
 
   
 
  stage lasts about three or four months. At the end of this time the adult frog leaves the water.  
 
   
 
  insect metamorphosis  
 
   
 
  Many insects hatch out of their eggs as larvae (an immature stage, usually in the form of a caterpillar, grub, or maggot) and have to pass through further major physical changes (metamorphosis) before reaching adulthood. An insect about to go through metamorphosis hides itself or makes a cocoon in which to hide, then rests while the changes take place; at this stage the insect is called a pupa, or a chrysalis if it is a butterfly or moth. When the changes are complete, the adult insect emerges.  
 
   
 
  Animal Behavior  
 
   
 
  communication  
 
   
 
  Animals communicate by signaling information, usually with the intention of altering the recipient's behavior, for example to drive away a rival or to attract a mate. Signals used in communication may be visual (such as the colorful plumage in birds, or a submissive or aggressive stance), auditory (for example the whines or barks of a dog), olfactory (such as the odors released by the scent glands of a deer), electrical (as in the pulses emitted by electric fish), or tactile (for example, the nuzzling of male and female elephants).  
 
   
 
  Bees transmit information to each other about  
 
   
 
  0402-02.jpg  
 
   
 
  bird of paradise The male blue bird of paradise displays to the female high up
in the tree canopy. It swings upside down, exposing its bright blue plumage
and tail streamers, at the same time uttering low mechanical-sounding cries.
 
 

 

 

 

   
Page 403
   
 
  food sources by "dances," each movement giving rise to sound impulses which are picked up by tiny hairs on the back of a bee's head, the orientation of the dance also having significance.  
 
   
 
  courtship  
 
   
 
  Courtship is the behavior exhibited by animals as a prelude to mating. The behavior patterns vary considerably from one species to another, but are often ritualized forms of behavior not obviously related to courtship or mating (for example, courtship feeding in birds). Courtship rituals include displays of strength or beauty, dances, and so on. Male bower-birds build elaborate bowers of sticks and grass, decorated with shells, feathers, or flowers, and even painted with the juice of berries, to attract the females. Some frogs, lizards, and even birds (such as the male frigate bird) have inflatable throat sacs, often red in color, which they puff out to lure a female. Courtship ensures that copulation occurs with a member of the opposite sex of the right species. It also synchronizes the partner's readiness to mate and allows each partner to assess the suitability of the other.  
 
courtship
   
 
  Birds often use color in courtship rituals. The kea uses red objects including artificial objects such as buttons; the male satin bower bird uses blue objects; the fairy wren uses a yellow flower.  
 


 

   
 
  migration  
 
   
 
  Certain animals, chiefly birds and fish, undertake long journeys, either as a seasonal movement or as part of a single life cycle, to distant breeding or feeding grounds. The precise methods by which animals navigate and know where to go are still obscure. Birds have much sharper eyesight and better visual memory of ground clues than humans, but in long-distance flights appear to navigate by the Sun and stars, possibly in combination with a "reading" of the earth's magnetic field through an inbuilt "magnetic compass," a tiny mass of tissue between the eye and brain. Similar cells occur in "homing'' honeybees. Leatherback turtles use the contours of underwater mountains and valleys to navigate by. Most striking, however, is the migration of young birds that have never flown a route before and are unaccompanied by adults. It is postulated that they may inherit as part of their genetic code an overall "sky chart" of their journey that is triggered into use when they become aware of how the local sky pattern, above  
 
lobster
   
 
  When spiny lobsters migrate, they do so by walking in queues of up to 65 along the sea-bed, each clinging with its claws to the rear of the one in front. Scientific experiments with dead lobsters, weights and pulleys have shown that such a arrangement reduces drag and allows a 25% improvement in speed through the water.  
 


 

   
 
  0403-01.jpg  
 
   
 
  migrating wildebeest During the dry season, herds of tens of thousands
of wildebeest embark on migrations of up to 1,600 km/1,000 mi in search
of water and grazing. Females and young stay in the center
of the herd, with the males defending the edges. Corbis
 
 

 

 

 

   
Page 404
   
 
  0404-01.jpg  
 
   
 
  bonnet macaques Bonnet macaques Macaca radiata from southern India usually spend
the hottest part of the day grooming each other. This helps not only to keep their skins
free of parasites but also to strengthen social relationships. Premaphotos Wildlife
 
 
   
 
  the place in which they hatch, fits into it. Similar theories have been advanced in the case of fish, such as eels and salmon, with whom vision obviously plays a lesser role, but for whom currents and changes in the composition and temperature of the sea in particular locations may play a part—for example, in enabling salmon to return to the precise river in which they were spawned. Migration also occurs with land animals such as lemmings and antelope.  
 
   
 
  social behavior  
 
   
 
  Social behavior among animals allows them to live harmoniously in groups by establishing hierarchies of dominance to discourage disabling fighting. It may be aggressive or submissive (for example cowering and other signals of appeasement), or designed to establish bonds (such as social grooming or preening).  
 
   
 
  The social behavior of mammals and birds is generally more complex than that of lower organisms and involves relationships with individually recognized animals. Thus, courtship displays allow individuals to choose appropriate mates and form the bonds necessary for successful reproduction. In the social systems of bees, wasps, ants, and termites, an individual's status and relationships with others are largely determined by its biological form, as a member of a caste of workers, soldiers, or reproductives.  
 
Biodiversity: Number of Species Worldwide
 
number identified
 
 
  % of estimated
total number of species
 
 
microorganisms
5,800
 
 
  3–27%  
 
invertebrates
1,021,000
 
 
  3–27%  
 
plants
322,500
 
 
  67–100%  
 
fish
19,100
 
 
  83–100%  
 
birds
9,100
 
 
  94–100%  
 
reptiles and amphibians
12,000
 
 
  90–95%  
 
mammals
4,000
 
 
  90–95%  
 
total
1,393,500
 
 
number of species
 
 
  % identified  
 
low estimate of all species
4.4 million
 
 
  31  
 
high estimate of all species
80 million
 
 
  2  
 


 

 

 

 

   
Page 405
Selected Animals on the Endangered and Threatened Species List for the World
Source: U.S. Fish and Wildlife Service
(Data as of April 1997.)
Common name Scientific name Range When listed
armadillo, giant Priodontes maximus (= giganteus) South America June 24, 1976
bear, brown Ursus arctos arctos Europe June 24, 1976
bear, brown Ursus arctos pruinosus Asia June 24, 1976
bear, Mexican grizzly Ursus arctos (= U. a. nelsoni ) North America June 2, 1970
bison, wood Bison bison athabascae North America June 2, 1970
bobcat Felis rufus escuinapae North America June 24, 1976
camel, Bactrian Camelus bactrianus (=ferus) Asia June 24, 1976
cat, leopard Felis bengalensis bengalensis Asia June 24, 1976
deer, pampas Ozotoceros bezoarticus South America June 24, 1976
dugong Dugong dugon Africa December 2, 1970
duiker, Jentink's Cephalophus jentinki Africa June 25, 1979
eland, western giant Taurotragus derbianus derbianus Africa June 25, 1979
elephant, African Loxodonta africana Africa May 12, 1978
elephant, Asian Elephas maximus Asia June 24, 1974
gazelle, Clark's (Dibatag) Ammodorcas clarkei Africa June 2, 1970
gorilla Gorilla gorilla Africa June 2, 1970
kangaroo, Tasmanian forester Macropus giganteus tasmaniensis Australia June 4, 1973
lemurs Lemuridae Africa June 2, 1970, June 14, 1976,
June 24, 1976
leopard Panthera pardus Africa, Asia June 2, 1970, March 30, 1972, January 28, 1982
leopard, snow Panthera uncia Asia March 30, 1972
manatee, Amazonian Trichechus inunguis South America June 2, 1970
manatee, West African Trichechus senegalensis Africa July 20, 1979
monkey, black howler Alouatta pigra North America October 19, 1976
monkey, red-backed squirrel Saimiri oerstedü South America June 2, 1970
monkey, spider Ateles geoffroyi frontatus South America June 2, 1970
mouse, Shark Bay Pseudomys praeconis Australia December 2, 1970
orangutan Pongo pygmaeus Asia June 2, 1970
panda, giant Ailuropoda melanoleuca Asia January 23, 1984
rat-kangaroo, Queensland Bettongia tropica Australia December 2, 1970
rhinoceros, black Diceros bicornis Africa July 14, 1980
rhinoceros, great Indian Rhinoceros unicornis Asia December 2, 1970
seal, Saimaa Phoca hispida saimensis Europe July 28, 1993
sloth, Brazilian three-toed Bradypus torquatus South America June 2, 1970
tapir, Asian Tapirus indicus Asia June 24, 1974
tapir, mountain Tapirus pinchaque South America June 2, 1970
tiger Panthera tigris Asia June 2, 1970, March 30, 1972
tiger, Tasmanian (thylacine) Thylacinus cynocephalus Australia June 2, 1970
wallaby, banded hare Lagostrophus fasciatus Australia December 2, 1970
whale, blue Balaenoptera musculus Oceanic June 2, 1970
whale, bowhead Balaena mysticetus Oceanic June 2, 1970
whale, finback Balaenoptera physalus Oceanic June 2, 1970
whale, humpback Megaptera novaeangliae Oceanic June 2, 1970
whale, right Balaena glacialis (incl. australis) Oceanic June 2, 1970
whale, sperm Physeter macrocephalus (=catodon) Oceanic June 2, 1970
wombat, hairy-nosed (Barnard's and Queensland hairy-nosed) Lasiorhinus krefftü (formerly L. Barnardi and L.gillespiei) Australia December 2, 1970, June 4, 1973
zebra, Grevy's Equus grevyi Africa August 21, 1979
zebra, mountain Equus zebra zebra Africa June 24, 1976, February 10, 1981
booby, Abbott's Sula abbotti Asia June 24, 1976
condor, Andean Vultur gryphus South America December 2, 1970
crane, hooded Grus monacha Asia December 2, 1970
crane, Japanese Grus japonenis Asia June 2, 1970
crane, whooping Grus americana North America March 11, 1967, and other dates


 

   
 
  (table continued on next page)  
 

 

 

 

   
Page 406
   
 
  (table continued from previous page)  
 
Common name Scientific name Range When listed
eagle, harpy Harpia harpyja South America June 24, 1976
egret, Chinese Egretta eulophotes Asia June 2, 1970
falcon, American peregrine Falco peregrinus anatum North America October 13, 1970
hawk, Galapagos Buteo galapagoensis South America June 2, 1970
ibis, Japanese crested Nipponia nippon Asia June 2, 1970
ibis, northern bald Geronticus eremita Africa, Asia, Europe September 28, 1990
macaw, glaucous Anodorhynchus glaucus South America June 24, 1976
macaw, indigo Anodorhynchus leari South America June 24, 1976
ostrich, Arabian Struthio camelus syriacus Asia June 2, 1970
ostrich, West African Struthio camelus spatzi Africa June 2, 1970
parakeet, gold-shouldered (hooded) Psephotus chrysopterygius Australia June 2, 1970
parakeet, Norfolk Island Cyanoramphus novaezelandiae cookü Australia September 28, 1990
parrot, ground Pezoporus wallicus Australia June 4, 1973
parrot, red-capped Pionopsitta pileata South America June 24, 1976
stork, oriental white Ciconia ciconia boyciana Asia June 2, 1970
woodpecker, imperial Campephilus imperialis North America June 2, 1970
woodpecker, Tristam's Drycopus javenis richardsi Asia June 2, 1970
alligator, Chinese Alligator sinensis Asia June 24, 1976
caiman, Apaporis River Caiman crocodilus apaporiensis South America June 24, 1976
crocodile, African dwarf Osteolaemus tetraspis tetraspis Africa June 24, 1976
crocodile, African slender-snouted Crocodylus cataphractus Africa March 30, 1972
crocodile, Morelet's Crocodylus moreletü South America June 2, 1970
iguana, Barrington land Conolophus pallidus South America June 2, 1970
lizard, Hierro giant Gallotia simonyi simonyi Europe February 29, 1984
lizard, Ibiza wall Podarcis pityusensis Europe February 29, 1984
monitor, Bengal Varanus bengalensis Asia June 24, 1976
monitor, desert Varanus griseus Africa June 24, 1976
monitor, yellow Varanus flavescens Asia June 24, 1976
python, Indian Python molurus molurus Asia June 24, 1976
tartaruga Podocnemis expansa South America June 2, 1970
tortoise, Bolson Gopherus flavomarginatus North America April 17, 1979
tortoise, Galapagos Geochelone elephantopus South America June 2, 1970
tuatara Sphenodon punctatus Australia June 2, 1970
turtle, aquatic box Terrapene coahuila North America June 4, 1973
turtle, green sea Chelonia mydas (incl. agassizi) North America (circumglobal) July 28, 1978
viper, Lar Valley Vipera latiffi Asia June 22, 1983
frog, Goliath Conraua goliath Africa December 8, 1994
frog, Israel painted Discoglossus nigriventer Europe June 2, 1970
frog, Panamanian golden Atelopus varius zeteki South America June 24, 1976
frog, Stephen Island Leiopelma hamiltoni Australia June 2, 1970
salamander, Chinese giant Andrias davidianus davidianus western China June 24, 1976
salamander, Japanese giant Andrias davidianus japonicus Japan June 24, 1976
toad, African viviparous Nectophrynoides spp. Africa June 24, 1976
toad, Cameroon Bufo superciliaris Africa June 24, 1976
toad, Monte Verde Bufo periglenes South America June 24, 1976


 

 

 

 

   
Page 407
   
 
  The Animal Kingdom Chronology  
 
The Animal Kingdom Chronology
c. 1140 B.C. Chinese emperor Wen Wang establishes the first zoo. It covers 1,500 acres and is named the Ling-Yo/Garden of Intelligence.
c. 1115 B.C. King Tiglath-Pileser I of Assyria collects wild animals, including the Egyptian gift of a crocodile.
280 B.C. The Egyptian pharaoh Ptolemy II has a large zoological garden at Alexandria, Egypt.
c. 150 Physiologus/Naturalist, a Greek work by an anonymous author, is written in Alexandria. All the medieval "bestiaries" evolve from this work, which is an encyclopedia of real and imagined natural history.
c. 1115 King Henry I of England establishes a menagerie at Woodstock, Oxfordshire; it features lions, camels, and leopards.
1220 Giraffes are brought to Europe and put on public display for the first time, to general amazement.
c. 1297 The moa, a giant flightless bird of New Zealand, is hunted to extinction by the Maori settlers on North Island, although it is though to have survived a while longer on South Island.
1517 Taxidermy is developed in Amsterdam, the Netherlands, where naturalists preserve cassowary birds brought from the East Indies.
1551 Swiss scientist Conrad Gesner publishes the first volume of his Historia animalium/History of Animals, a pioneering, highly illustrated, classification of animals.
1599 The Italian naturalist Ulisse Aldrovandi publishes the first three volumes of his Natural History, methodically listing and describing bird species in the first serious zoological study.
1669 Dutch microscopist Jan Swammerdam writes a History of Insects, which lists the reproductive parts of insects and correctly describes metamorphosis.
1669 Italian anatomist Marcello Malpighi publishes a treatise on the anatomy and development of the silkworm, the first description of the anatomy of an invertebrate.
1681 The dodo, a form of giant pigeon inhabiting the island of Mauritius in the Indian Ocean, is driven to extinction by the arrival of colonizing Europeans.
1693 English naturalist John Ray, introduces the first important classification system for animals.
1734 French scientist René-Antoine Ferchault de Réaumur publishes History of Insects, a founding work of entomology.
1740 Swiss naturalist Abraham Trembley discovers the hyera—a simple water organism combining plant and animal characteristics, and capable of regenerating itself.
1758 Swedish naturalist Carolus Linnaeus applies the binomial taxonomy he developed for plant classification to animal species.
1760 Dutch naturalist and engraver Pieter Lyonnet publishes a monograph on the goat-moth caterpillar, containing details and illustrations of dissections. It is one of the best illustrated books on anatomy ever produced and describes over 4,000 muscles.
1760 French naturalist M. Brisson publishes his Ornithologie/Ornithology, a classic study of bird life.
1768 Italian physiologist Lazzaro Spallanzani studies regeneration in animals and shows that the lower animals have a greater capacity to regenerate lost limbs.
1775 Italian anatomist Johann Fabricius classifies insects according to their mouth structure rather than their wings.
1793 French naturalist Jean-Baptiste Lamarck argues that fossils are the remains of extremely ancient, extinct species of animals and plants.
1794 English naturalist and physician Erasmus Darwin publishes Zoonomia, or the Laws of Organic Life, expressing his ideas on evolution (which he assumes has an environmental cause).
1797 The English wood engrave Thomas Bewick publishes Land Birds. It is the first part of his work A History of British Birds.
1802–1805 French zoologist Pierre-André Latreille publishes his 14-volume work Histoire naturele générale et particulière des crustacés et insectes/Comprehensive Natural History of Crustaceans and Insects.
1812 French zoologist Georges Cuvier, publishes Researches sur les ossements fossiles de quadrupèdes/Research on the Fossil Bones of Quadrupeds, and establishes comparative vertebrate paleontology. He theorizes that the extinction of species has been caused by great catastrophes such as sudden land upheavals and floods.
1817 Cuvier breaks away from the view that animals can be arranged in a linear sequence leading to humans and argues instead that they should be classified according to their anatomical organization.
1826 English administrator Stamford Raffles founds the Royal Zoological Society in London, England,
1827–1838 U.S. ornithologist John James Audubon publishes the first volume of his multi-volume work Birds of America.
1828 London Zoo opens in Regent's Park, London, England.
Dec 27, 1831 Oct –2, 1836 The English naturalist Charles Darwin undertakes a five-year voyage, to South


 

 

 

 

   
Page 408
  America and the Pacific, as naturalist on the Beagle. The voyage convinces him that species have evolved gradually but he waits over 20 years to publish his findings.
1846 English paleontologist Richard Owen publishes Lectures on Comparative Anatomy and Physiology of the Vertebrate Animals, one of the first textbooks on comparative vertebrate anatomy.
1854 English naturalist Philip Henry Gosse builds the first institutional aquarium in England for the protection of marine animals.
1855–1856 Gosse publishes Manual of Marine Zoology, the first thorough book on the subject.
Nov 24, 1859 Charles Darwin publishes On the Origin of Species by Natural Selection, which expounds his theory of evolution by natural selection.
1861 English entomologist H. W. Bates publishes his paper "Contributions to the Insect Fauna of the Amazon Valley," in which he describes many of the over 14,000 insects (8,000 of which had previously been unknown) that he has collected.
1868 English naturalist Thomas Henry Huxley makes the first classification of the dinosaurs, creating the order Ornithoscelida and two suborders.
Dec 7, 1872–May 26, 1876 The British ship Challenger undertakes the world's first major oceanographic survey. Under the command of the Scottish naturalist Wyville Thomson, it discovers hundreds of new marine animals, and finds that at 2,000 fathoms the temperature of the ocean is a constant 2.5°/C/36.5°F.
1878 The complete skeletons of several dozen Iguanodon are discovered in a coal mine in Belgium. They provide the first evidence that some dinosaurs traveled in herds.
1887 English naturalist H. G. Seeley classifies the dinosaurs into two groups, those with birdlike pelvises, the Ornithischia, and those with reptile-like pelvises, the Saurischia.
1915–1916 English naturalist Archibald Thorburn publishes British Birds, which describes and catalogs the birdes in Britain.
1919 Austrian zoologist Karl von Frisch discovers that bees communicate the location of nectar through wagging body movements and rhythmic dances.
1935 Austrian zoologist Konrad Lorenz founds the discipline of ethology by describing the learning behavior of young ducklings; visual and auditory stimuli from the parent object cause them to "imprint" on the parent.
1938 A coelacanth, an ancient lobe-finned fish assumed to be extinct, is discovered in the Indian Ocean.
1960 English primatologist Jane Goodall discovers that chimpanzees can make tools, something only humans were thought capable of. She watches a chimpanzee fashion a blade of grass into a probe that can be poked into a termite mound to remove termites.
1964 U.S. zoologist William Hamilton recognizes the importance of altruistic behavior in animals, paving the way for the development of sociobiology.
1967 U.S. biochemist Marshall Nirenberg establishes that mammals, amphibians, and bacteria all share a common genetic code.
1972 The United States restricts the use of DDT because it is discovered that it thins the eggshells of predatory birds, lowering their reproductive rates.
1973 Kenya bans hunting elephants and trading in ivory.
1973 Representative from 80 nations sign the Convention on International Trade in Endangered Species (CITES) that prohibits trade in 375 endangered species of plants and animals and the products derived from them, such as ivory; the United States does not sign until 1977.
1973 The U.S. Fish and Wildlife Bureau issues the first Endangered and Threatened Species List.
1977 Scientists discover chemosynthetically based animal communities around sulfurous thermal springs deep under the sea near the Galápagos Islands, Ecuador.
1982 Dolphins are discovered to possess magnetized tissues that aid in navigation; they are the first mammals discovered to have such tissues.
1983 The first discovery of a fossil land mammal (a marsupial) in Antarctica is made.
1983 The skull of a creature called Pakicetus is discovered is Pakistan; estimated to be 50 million years old, it is intermediate in evolution between whales and land animals.
1984 Allan Wilson and Russell Higuchi of the University of California, Berkeley, United States clone genes from an extinct animal, the quagga.
1985 An amphibian skeleton dated 340 million years old in discovered is Scottish oil shale. It is the earliest well-preserved amphibian found.


 

 

 

 

   
Page 409
1985 U.S. zoologist Dian Fossey, who tried to protect endangered gorillas in Rwanda, is murdered. Poachers are suspected.
1989 A lemur, Allocebus tricholis, previously thought to be extinct, is discovered in Madagascar.
1989 The United Nations Environment Programme (UNEP) reports that the number of species, and the amount of genetic variation within individual species, is decreasing due to the rapid destruction of natural environments.
1992 The tooth of a 55-million-year-old mammal is discovered at Murgon, Australia, indicating that mammals arrived in Australia at about the same time as marsupials.
1993 U.S. and Pakistani paleontologists discover in Pakistan a fossil whale which is about the size of an adult male sea lion and has legs. Called Ambulocetus, it is 50 million years old and was able to walk on land but spent most of its time in the sea.
1994 A new species of kangaroo is discovered in Papua New Guinea. Known locally as the bondegezou, it weighs 15 kg/7 lb and is 1.2 m/3.9 ft in height.
1995 A fossil chordate Yunnanozoon lividum is discovered in Chengjiang, China. It is the first chordate recorded from the early Cambrian period and is 525 million years old.
1996 New Zealand ornithologist Gavin Hunt reveals that crows on the island of New Caledonia in the South Pacific make tools out of leaves and twigs which they use to reach insects in dead wood–something only chimpanzees and humans were thought capable of.
1996 Paleontologist from the University of Chicago discover, in Morocco, the remains of the largest carnivorous dinosaur known:
Carcharodontosaurus saharicus ("shark-toothed reptile from the Sahara"). It lived 90 million years ago, weighed 8 tons, ran at a speed of 32 kph/20 mph, and at 13.5 m/44 ft in length was 1 m/3.3 ft longer than Tyrannosaurus rex.
1996 The World Conservation Union (IUCN) publishes the latest Red List of endangered species. Over 1,000 mammals are listed, far more than on previous lists. The organization believes it has underestimated the risks of habitats from pollution and that the number of endangered species is greater than previously thought.
1996 British paleontologist Peter Ward announces the discovery, in South Africa, of the fossil remains of a lystrosaur, a pig-like early mammal which lived during the Permian era about 250 million years ago. The discovery overturns the existing theory that the first mammals were therapsids–small shrew-like creatures which emerged millions of years later during the age of the dinosaurs.
1996 Paleontologist from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China, discover the remains of a 135-million-year-old fossil bird in Northeast China. Called the "Confucius bird" (Confusciusornis sactus), it had a modern-looking beak with no teeth, unlike Archeopteryx.
1997 In a coal mine in southern Thailand, Thai researchers discover fragments of lower and upper jaws and teeth of a medium-sized monkey-like creature that lived about 40 million years ago. Known as Siamopithecus eocaenus ("dawn ape from Thailand"), it weighed 6–7 kg/13–15 lb and provides some of the earliest evidence for the evolution of monkeys, apes, and humans.
1997 U.S. zoologists Bill Detrich and Kirk Malloy show that the increased ultraviolet radiation caused by the hole in the ozone layer above Antarctica kills large numbers of fish in the Southern Ocean. Because their transparent eggs and larvae stay near the surface for up to a year, they are exposed to the full force of the ultraviolet rays. It is the first time ozone depletion in the Antarctic has been shown to harm organisms larger than one-celled marine plants.
June 9–29, 1997 At the tenth Convention on International Trade in Endangered Species (CITES) convention in Harare, Zimbabwe, the elephant is downlisted to CITES Appendix II (vulnerable) and the ban on ivory exportation in Botswana, Namibia, and Zimbabwe is lifted.
1997 Scientists from the Worldwide Fund for Nature (WWF) announce the discovery of a new species of muntjac deer in Vietnam. A dwarf species weighing only about 16 kg/35 lb, it has antlers the length of a thumbnail and lives at altitudes of 457–914 m/1,500–3,000 ft.
1998 U.S. ornithologists announce the discovery of a new species of bird Ecuador belonging to the genus Antpitta; this is claimed to be the most important species of bird discovered in 50 years.


 

 

 

 

   
Page 410
   
 
  Biographies  
 
   
 
  Adamson, Joy Friedericke Victoria (born Gessner) (1910–1985) German-born naturalist whose work with wildlife in Kenya, including the lioness Elsa, is described in the book Born Free (1960). She was murdered at her home in Kenya. She worked with her third husband, British game warden George Adamson (1906–1989), who was murdered by bandits.  
 
   
 
  Andrews, Roy Chapman (1884–1960) U.S. zoologist. He is best known for his discovery of the oldest known mammals and extensive evidence of primitive human life in the central Asiatic plateau. He was the first to find fossilized dinosaur eggs, and the skull and other skeletal parts of the Baluchitherium, the largest known mammal. Andrews proved central Asia to be one of the chief centers of the origin and distribution of reptilian and mammalian life.  
 
   
 
  Attenborough, David (1926– ) English naturalist who has made numerous wildlife films for television. He was the writer and presenter of the television series Life on Earth (1979), illustrating evolution; The Living Planet (1983), dealing with ecology and the environment; The Trials of Life (1990), describing life cycles; Life in the Freezer (1993); The Private Life of Plants (1995); and The Life of Birds (1998).  
 
   
 
  Audubon, John James (1785–1851) U.S. naturalist and artist. In 1827, after extensive travels and observations of birds, he published the first part of his Birds of North America, with a remarkable series of color plates. Later he produced a similar work on North American quadrupeds.  
 
   
 
  Bates, H(enry) W(alter) (1825–1892) English naturalist and explorer. He spent 11 years collecting animals and plants in South America and identified 8,000 new species of insects. He made a special study of camouflage in animals, and his observation of insect imitation of species that are unpleasant to predators is known as "Batesian mimicry."  
 
   
 
  Beebe, (Charles) William (1877–1962) U.S. naturalist, explorer, and writer. His interest in deep-sea exploration led to a collaboration with the engineer Otis Barton and the development of a spherical diving vessel, the bathysphere. On August 24, 1934 the two men made a record-breaking dive to 923 m/3,028 ft. Beebe was curator of birds for the New York Zoological Society 1899–1952. He wrote the comprehensive Monograph of the Pheasants (1918–22), and his expeditions are described in a series of memoirs.  
 
   
 
  Buffon, George Louis Leclerc, Comte de (1707–1778) French naturalist and author of the 18th century's most significant work of natural history, the 44-volume Histoire naturelle (1749–67). In The Epochs of Nature, one of the volumes, he questioned biblical chronology for the first time and raised the earth's age from the traditional figure of 6,000 year to the seemingly colossal estimate of 75,000 years.  
 
   
 
  Carter, Herbert James (1858–1940) Australian entomologist, born in England. A schoolteacher, he became interested in entomology, particularly beetles, and was an avid collector and classifier, describing over 1,000 new species. He was joint editor of the first Australian Encyclopaedia (1925–27), supervising the science articles. His published work includes 65 papers and the book Gulliver in the Bush (1933), recording his field experiences in Australia.  
 
   
 
  Cousteau, Jacques Yves (1910–1997) French oceanographer who pioneered the invention of the aqualung in 1943 and techniques in underwater filming. In 1951 he began the first of many research voyages in the ship Calypso. His film and television documentaries and books established him as a household name.  
 
   
 
  Darwin, Charles Robert (1809–1882) English naturalist who developed the modern theory of evolution and proposed, with Alfred Russel Wallace, the principle of natural selection. After research in South America and the Galápagos Islands as naturalist on HMS Beagle 1831–36, Darwin published On the Origin of Species by Means of Natural Selection or the Preservation of Favoured Races in the Struggle for Life (1859). This book explained the evolutionary process through the principles of natural selection and aroused bitter controversy because it disagreed with the literal interpretation of the Book of Genesis in the Bible.  
 
   
 
  Durrell, Gerald (Malcolm) (1925–1995) English naturalist, writer, and zoo curator. He founded the Jersey Zoological Park in 1958. Critical of the conditions in which most zoos kept animals, the lack of interest in breeding programs, and the concentration on large species, such as the big cats, rhinos, and elephants, Durrell became determined to build up his own zoo, and to run it so that it could supplement conservation programs in the wild rather than detract from them. Through his work, Durrell encouraged and inspired a whole generation of naturalists, zoologists, and zoo keepers.  
 
   
 
  Ehrenberg, Christian Gottfried (1795–1876) German naturalist who developed one of the forerunners of the modern scheme for classification of the animal kingdom. He was the first scientist to study the fossils of microorganisms and can be regarded as the founder of micropaleontology.  
 
   
 
  Fabre, Jean Henri Casimir (1823–1915) French entomologist whose studies of wasps, bees, and other insects, particularly their anatomy and behavior, have become classics. In addition to numerous entomological papers, Fabre wrote the tenvolume Souvenirs entomologiques (1879–1907). Based almost entirely on observations made in his small plot of land in Provence, this work is a model of meticulous attention to detail.  
 
   
 
  Fabricus, Johann Christian (1745–1808) Danish entomologist who developed a classification system for insects. Using the mouth structure as the basis for classification, he named and described over 10,000 insects. He also wrote on evolution, long before Darwin, and was convinced that humans had evolved from the great apes.  
 
   
 
  Fossey, Dian (1938–1985) U.S. zoologist. Almost completely untrained, Fossey was sent by Louis Leakey into the African wild. From 1975 she studied mountain gorillas in Rwanda and discovered that they committed infanticide and that females were transferred to nearly established groups. Living in close proximity to them, she discovered that they led peaceful family lives. She was murdered by poachers whose snares she had cut.  
 

 

 

 

   
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  Frisch, Karl von (1886–1982) Austrian zoologist, founder with Konrad Lorenz of ethology, the study of animal behavior. He specialized in bees, discovering how they communicate the location of sources of nectar by movements called "dances." He was awarded the Nobel Prize for Physiology or Medicine in 1973 together with Lorenz and Nikolaas Tinbergen.  
 
   
 
  Gesner, Konrad von (1516–1565) Swiss naturalist. He produced an encyclopedia of the animal world, the five-volume Historia animalium (1551–58), and is considered the founder of zoology.  
 
   
 
  Geoffroy Saint-Hilaire, Isidore (1805–1861) French zoologist and anatomist who specialized in the study of apes and developed a system for their classification. He also studied the manner in which animals interact with their environments. In 1859 he wrote a history of the origin of species which put Darwin's proposals in the context of his French predecessors, including Buffon, Lamarck and Etienne Geoffroy SaintHilaire.  
 
   
 
  Goodall, Jane (1934– ) English primatologist and conservationist who has studied the chimpanzee community on Lake Tanganyika, Africa, since 1960, and is a world authority on wild chimpanzees. She observed the lifestyles of chimpanzees in their natural habitats, discovering that they are omnivores, not herbivores as originally thought, and that they have highly developed and elaborate forms of social behavior. In the 1990s most of Goodall's time was devoted to establishing sanctuaries of illegally captured chimpanzees, fundraising, and speaking out against the unnecessary use of animals in research. Her books include In the Shadow of Man (1971), The Chimpanzees of Gombe: Patterns of Behavior (1986), and Through a Window (1990).  
 
   
 
  Gosse, Philip Henry (1810–1888) English naturalist who built the first aquarium ever used to house marine animals longterm and wrote many books on marine zoology, including Manual of Marine Zoology (1855), Actinologia Britannica (1858), a work on sea anemones, Introduction to Zoology (1843), and Evenings at the Microscope (1859).  
 
   
 
  Gould, John (1804–1881) English zoologist who with his wife Elizabeth (1804–1841), a natural-history artist, published a successful series of illustrated bird books. They visited Australia 1838–40 and afterwards produced The Birds of Australia, issued in 36 parts from 1840. Mammals of Australia followed (1845–63), and Handbook to the Birds of Australia (1865).  
 
   
 
  Griffin, Donald Redfield (1915– ) U.S. zoologist who discovered that bats use echolocation to navigate and orientate themselves in space, that is they emit ultrasonic sounds that rebound off objects that they are then able to avoid. His later research was mainly in the areas of animal navigation, acoustic orientation and sensory biophysics, and animal consciousness. His writing includes Listening in the Dark (1958), Echoes of Bats and Men (1959), Animal Structure and Function (1962), Bird Migration (1964), and The Question of Animal Awareness (1976).  
 
   
 
  Hyman, Libbie Henrietta (1888–1969) U.S. zoologist whose six-volume The Invertebrates (1940–68) provided an encyclopedic account of most phyla of invertebrates.  
 
   
 
  Knight, Charles (1874–1953) U.S. paleontological artist who was influential in bringing dinosaurs to life in the public imagination. His extensive knowledge of anatomy and his collaborations with paleontologists, such as Edward Drinker Cope and Henry Fairfield Osborn, mean his paintings accurately reflect scientific thinking of the time.  
 
   
 
  Lack, David (1910–1973) English ornithologist who used radar to identify groups of migrating birds. He studied and wrote about the robin, the great tit, the swift, and the finches of the Galápagos Islands. He was the director of the Edward Grey Institute of Field Ornithology at Oxford from 1945 and received the Royal Society's Darwin medal in 1972.  
 
   
 
  Leuckart, Karl Georg Friedrich Rudolf (1822–1898) German zoologist who identified the phylum Coelenterata (now divided into separate phyla, the Cnidaria—jellyfish, sea anemones, and corals—and the Ctenophora—the comb jellies). His research led to the division of the Metazoa (multicellular animals) into Coelenterata, Echinodermata (sea urchins), Annelida (segmented worms), Arthropoda (jointed limbed animals including insects, spiders, crabs, and lobsters), Mollusca (mollusks, including slugs, snails, octopuses, and shellfish), and Vertebrata (animals with backbones, including fish, birds, and mammals).  
 
   
 
  Lorenz, Konrad Zacharias (1903–1989) Austrian ethologist. He studied the relationship between instinct and behavior, particularly in birds, and described the phenomenon of imprinting in 1935. His books include King Solomon's Ring (1952), on animal behavior. In 1973 he shared the Nobel Prize for Physiology or Medicine with Nikolaas Tinbergen and Karl von Frisch.  
 
   
 
  Manton, Sidnie Milana (married name Harding) (1902–1979) English embryologist who specialized in the arthropods (jointed limbed animals including insects, spiders, crabs, and lobsters), concentrating mainly on their embryology and functional morphology in relation to evolution. She summarized her findings in her book The Arthropoda: Habits, Functional Morphology and Evolution (1977).  
 
   
 
  Mayr, Ernst Walter (1904– ) German-born U.S. zoologist who was influential in the development of modern evolutionary theories. He led a two-year expedition to New Guinea and the Solomon Islands where he studied the effects of founder populations and speciation on the evolution of the indigenous birds and animals. This research caused him to support neo-Darwinism, a synthesis of the ideas of Darwin and Mendel, being developed at that time. He has written and edited a number of books, including several upon the development of evolutionary thought, which are standard texts on university courses.  
 
   
 
  Morgan, Ann Haven (1882–1966) U.S. zoologist who promoted the study of ecology and conservation. She particularly studied the zoology of aquatic insects and the comparative physiology of hibernation. Her Field Book of Ponds and Streams: An Introduction to the Life of Fresh Water (1930) attracted amateur naturalists as well as providing an authoritative taxonomic guide for professionals.  
 
   
 
  Morris, Desmond John (1928– ) British zoologist, a writer and broadcaster on animal and human behavior. His book The Naked Ape (1967) was a best seller. In his book The Human Zoo (1969), Morris compares civilized humans with  
 

 

 

 

   
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  their captive animal counterparts and shows how confined animals seem to demonstrate the same neurotic behavior patterns as human beings often do in crowded cities.  
 
   
 
  Nice, Margaret, born Morse (1883–1974) U.S. ornithologist who made an extensive study of the life history of the sparrow. She also campaigned against the indiscriminate use of pesticides.  
 
   
 
  Pallas, Peter Simon (1741–1811) German naturalist who classified corals and sponges and whose work in comparative anatomy, including Zoographia Rosso-Asiatica, established him as a predecessor of the French comparative anatomist and founder of paleontology Georges Cuvier.  
 
   
 
  Pye, John David (1932– ) English zoologist who has studied the way bats use echolocation, and also the use of ultrasound in other animals. In 1971 he calculated the resonant frequencies of the drops of water in fog and found that these frequencies coincided with the spectrum of frequencies used by bats for echolocation. In other words, bats cannot navigate in fog. Pye also found that ultrasound seems to be important in the social behavior of rodents and insects.  
 
   
 
  Rothschild, Miriam (1908– ) English zoologist and entomologist. She studied fleas and was the first to work out the flea jumping mechanism. She also studied fleas' reproductive cycles and linked this, in rabbits, to the hormonal changes within the host. She has written around 350 papers on entomology, zoology, neurophysiology, and chemistry. Still active in her eighties, she worked on plants and studied the telepathic relationship between people and their pets. Her interest in animal consciousness has led her to press for reform in the treatment of animals in agriculture.  
 
   
 
  Sutton-Pringle, John William (1912–1982) British zoologist who established much of our knowledge of the anatomical mechanisms involved in insect flight.  
 
   
 
  Swammerdam, Jan (1637–1680) Dutch naturalist who is considered a founder of both comparative anatomy and entomology. Based on their metamorphic development, he classified insects into four main groups, three of which are still used in a modified form in insect classification. He accurately described and illustrated the life cycles and anatomies of many insect species, including bees, mayflies, and dragonflies.  
 
   
 
  Tinbergen, Niko(laas) (1907–1988) Dutch-born British zoologist. He specialized in the study of instinctive behavior in animals. One of the founders of ethology, the scientific study of animal behavior in natural surroundings, he shared a Nobel prize in 1973 with Konrad Lorenz (with whom he worked on several projects) and Karl von Frisch.  
 
   
 
  Tinbergen investigated other aspects of animal behavior, such as learning, and aggression. In The Study of Instinct (1951), he showed that the aggressive behavior of the male three-spined stickleback is stimulated by the red coloration on the underside of other males (which develops during the mating season). In The Herring Gull's World (1953) he described the social behavior of gulls, emphasizing the importance of stimulus-response processes in territorial behavior.  
 
   
 
  Turner, Charles Henry (1867–1923) U.S. biologist who carried out research into insect behavior patterns. He was the first to prove that insects can hear and distinguish pitch and that cockroaches learn by trial and error. He published over 50 papers on neurology, animal behavior, and invertebrate ecology, including his dissertation "The homing of ants: an experimental study of ant behavior" (1907).  
 
   
 
  von Gesner, Konrad Swiss naturalist. See c0016-01.gifGesner, Konrad von.  
 
   
 
  Waite, Edgar Ravenswood (1866–1928) Australian ornithologist and zoologist. He was a member of several expeditions into the subantarctic islands, New Guinea, and central Australia which contributed significantly to scientific knowledge of vertebrates. His published work includes more than 200 scientific papers, Popular Account of Australian Snakes (1898), and The Fishes of South Australia (1923).  
 
   
 
  Wilson, Edward Osborne (1929– ) U.S. zoologist whose books have stimulated interest in biogeography, the study of the distribution of species, and sociobiology, the evolution of behavior. He is a world authority on ants. His works include Sociobiology: The New Synthesis (1975) and The Diversity of Life (1992).  
 
   
 
  Wynne-Edwards, Vero Copner (1906– ) English zoologist who argued that animal behavior is often altruistic and that animals will behave for the good of the group, even if this entails individual sacrifice. His study Animal Dispersal in Relation to Social Behavior was published in 1962.  
 
   
 
  The theory that animals are genetically programed to behave for the good of the species has since fallen into disrepute. From this dispute grew a new interpretation of animal behavior, seen in the work of biologist Edward Wilson.  
 
   
 
  Young, J(ohn) Z(achary) (1907–1997) English zoologist who discovered and studied the giant nerve fibers in squids, contributing greatly to knowledge of nerve structure and function. He also did research on the central nervous system of octopuses, demonstrating that memory stores are located in the brain. He published the textbooks The Life of Vertebrates (1950) and The Life of Mammals (1957).  
 
   
 
  Zuckerman, Solly, Baron Zuckerman of Burnham Thorpe (1904–1993) South African-born British zoologist, educator, and establishment figure. He did extensive research on primates, publishing a number of books that became classics in their field, including The Social Life of Monkeys and Apes (1932) and Functional Affinities of Man, Monkeys and Apes (1933). He was chief scientific adviser to the British government 1964–71.  
 

 

 

 

   
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  Glossary  
 
   
 
  A  
 
   
 
  abdomen
in vertebrates, the part of the body containing the digestive organs; in insects and other arthropods, it is the hind part of the body. In mammals, the abdomen is separated from the thorax (containing the heart and lungs, protected by the rib cage) by the diaphragm, a sheet of muscular tissue; in arthropods, commonly by a narrow constriction. In mammals, the female reproductive organs are in the abdomen. In insects and spiders, it is characterized by the absence of limbs.
 
 
   
 
  afterbirth
in mammals, the placenta, umbilical cord, and ruptured membranes, which become detached from the uterus and expelled soon after birth.
 
 
   
 
  air sac
in birds, a thin-walled extension of the lungs. There are nine of these and they extend into the abdomen and bones, effectively increasing lung capacity. In mammals, it is another name for the alveoli in the lungs, and in some insects, for widenings of the trachea (airway).
 
 
   
 
  altruism
helping another individual of the same species to reproduce more effectively, as a direct result of which the altruist may leave fewer offspring itself. Female honey bees (workers) behave altruistically by rearing sisters in order to help their mother, the queen bee, reproduce, and forgo any possibility of reproducing themselves.
 
 
   
 
  ammonite
extinct marine cephalopod mollusk of the order Ammonoidea, related to the modern nautilus. The shell was curled in a plane spiral and made up of numerous gas-filled chambers, the outermost containing the body of the animal. Many species flourished between 200 million and 65 million years ago, ranging in size from that of a small coin to 2 m/6 ft across.
 
 
   
 
  antenna
an appendage (''feeler") on the head. Insects, centipedes, and millipedes each have one pair of antennae but there are two pairs in crustaceans, such as shrimps. In insects, the antennae are involved with the senses of smell and touch; they are frequently complex structures with large surface areas that increase the ability to detect scents.
 
 
   
 
  antler
"horn" of a deer, often branched, and made of bone rather than horn. Antlers, unlike true horns, are shed and regrown each year. Reindeer of both sexes grow them, but in all other types of deer, only the males have antlers.
 
 
   
 
  archeopteryx
extinct primitive bird, known from fossilized remains, about 160 million years old, found in limestone deposits in Bavaria, Germany. It is popularly known as "the first bird," although some earlier bird ancestors are now known. It was about the size of a crow and had feathers and wings, with three clawlike digits at the end of each wing, but in many respects its skeleton is reptilian (teeth and a long, bony tail) and very like some small meat-eating dinosaurs of the time.
 
 
   
 
  axolotl
aquatic larval form ("tadpole") of the Mexican salamander Ambystoma mexicanum, belonging to the family Ambystomatidae. Axolotls may be up to 30 cm/12 in long. Axolotls are remarkable because they can breed without changing to the adult form, and will metamorphose into adults only in response to the drying-up of their ponds. The adults then migrate to another pond.
 
 
   
 
  B  
 
   
 
  bat
any mammal of the order Chiroptera, related to the Insectivora (hedgehogs and shrews), but differing from them in being able to fly. Bats are the only true flying mammals. Their forelimbs are developed as wings capable of rapid and sustained flight. There are two main groups of bats: megabats, which eat fruit and microbats, which mainly eat insects. Although by no means blind, many microbats rely largely on echolocation for navigation and finding prey, sending out pulses of high-pitched sound and listening for the echo.
 
 
   
 
  beak
horn-covered projecting jaws of a bird (see bill), or other horny jaws such as those of the octopus, platypus, or tortoise.
 
 
   
 
  bee
four-winged insect of the superfamily Apoidea in the order Hymenoptera, usually with a sting. There are over 12,000 species, of which fewer than 1 in 20 are social in habit. The hive bee or honeybee Apis mellifera establishes perennial colonies of about 80,000, the majority being infertile females (workers), with a few larger fertile males (drones), and a single very large fertile female (the queen). Worker bees live for no more than a few weeks, while a drone may live a few months, and a queen several years. Queen honeybees lay two kinds of eggs: fertilized, female eggs, which have two sets of chromosomes and develop into workers or queens, and unfertilized, male eggs, which have only one set of chromosomes and develop into drones.
 
 
   
 
  beetle
common name of insects in the order Coleoptera with leathery forewings folding down in a protective sheath over the membranous hindwings, which are those used for flight. They pass through a complete metamorphosis. Comprising more than 50% of the animal kingdom, beetles number some 370,000 named species.
 
 
   
 
  bill
in birds, the projection of the skull bones covered with a horny sheath. It is not normally sensitive, except in some aquatic birds, rooks, and woodpeckers, where the bill is used to locate food that is not visible. The bills of birds are adapted by shape and size to specific diets, for example, shovelers use their bills to sieve mud in order to extract food; birds of prey have hooked bills adapted to tearing flesh; the bills of the avocet, and the curlew are long and narrow for picking tiny invertebrates out of the mud; and those of woodpeckers are sharp for pecking holes in trees and plucking out insects. The bill is also used by birds for preening, fighting, display, and nest-building.
 
 
   
 
  bioluminescence
production of light by living organisms. It is a feature of many deep-sea fishes, crustaceans, and other marine animals. On land, bioluminescence is seen in some nocturnal insects such as glow-worms and fireflies, and in certain bacteria and fungi. Light is usually produced by the oxidation of luciferin, a reaction catalyzed by the enzyme luciferase. Animal luminescence is involved in communication, camouflage, or the luring of prey.
 
 
   
 
  birth
act of producing live young from within the body of female animals. Both viviparous and ovoviviparous animals
 
 

 

 

 

   
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  give birth to young. In viviparous animals, embryos obtain nourishment from the mother via a placenta or other means.  
 
   
 
  bivalve
marine or freshwater mollusk whose body is enclosed between two shells hinged together by a ligament on the dorsal side of the body.
 
 
   
 
  bone
hard connective tissue comprising the skeleton of most vertebrate animals. Bone is composed of a network of collagen fibers impregnated with mineral salts (largely calcium phosphate and calcium carbonate), a combination that gives it great density and strength, comparable in some cases with that of reinforced concrete.
 
 
   
 
  brachiopod,
or lamp shell, any member of the phylum Brachiopoda, marine invertebrates with two shells, resembling but totally unrelated to bivalves. A single internal organ, the lophophore, handles feeding, aspiration, and excretion. There are about 300 living species.
 
 
   
 
  bug
in entomology, an insect belonging to the order Hemiptera. All these have two pairs of wings with forewings partly thickened. They also have piercing mouthparts adapted for sucking the juices of plants or animals, the "beak" being tucked under the body when not in use.
 
 
   
 
  butterfly
insect belonging, like moths, to the order Lepidoptera, in which the wings are covered with tiny scales, often brightly colored. There are some 15,000 species of butterfly, many of which are under threat throughout the world because of the destruction of habitat.
 
 
   
 
  C  
 
   
 
  caecilian
tropical amphibian of wormlike appearance. There are about 170 species known in the family Caecilüdae, forming the amphibian order Apoda (also known as Gymnophiona). Caecilians have a grooved skin that gives a "segmented" appearance; they have no trace of limbs or pelvis. The body is 20–130 cm/8–50 in long, beige to black in color. The eyes are very small and weak or blind. They eat insects and small worms. Some species bear live young, others lay eggs.
 
 
   
 
  camel
large cud-chewing mammal of the even-toed hoofed order Artiodactyla. Unlike typical ruminants, it has a threechambered stomach. There are two species, the single-humped Arabian camel Camelus dromedarius and the twin-humped Bactrian camel C. bactrianus from Asia.
 
 
   
 
  camouflage
colors or structures that allow an animal to blend with its surroundings to avoid detection by other animals. Camouflage can take the form of matching the background color, of countershading (darker on top, lighter below, to counteract natural shadows), or of irregular patters that break up the outline of the animal's body. More elaborate camouflage involves closely resembling a feature of the natural environment, as with the stick insect; this is closely akin to mimicry.
 
 
   
 
  cane toad
toad of the genus Bufo marinus, family Bufonidae. Also known as the giant or marine toad, the cane toad is the largest in the world. It was introduced to Australia during the 1930s to eradicate the cane beetle, but has now itself become a pest in Australia.
 
 
   
 
  capybara
the world's largest rodent Hydrochoerus hydrochaeris, up to 1.3 m/4 ft long and 50 kg/110 lb in weight. It is found in South America, and belongs to the guinea-pig family. It inhabits marshes and dense vegetation around water.
 
 
   
 
  carnivore
mammal of the order Carnivora. Although its name describes the flesh-eating ancestry of the order, it includes pandas, which are herbivorous, and civet cats, which eat fruit.
 
 
   
 
  cartilage
flexible bluish-white connective tissue made up of the protein collagen. In cartilaginous fish it forms the skeleton; in other vertebrates it forms the greater part of the embryonic skeleton, and is replaced by bone in the course of development, except in areas of wear such as bone endings, and the discs between the backbones. It also forms structural tissue in the larynx, nose, and external ear of mammals.
 
 
   
 
  caterpillar
larval stage of a butterfly or moth. Wormlike in form, the body is segmented, may be hairy, and often has scent glands. The head has strong biting mandibles, silk glands, and a spinneret.
 
 
   
 
  cephalopod
any predatory marine mollusk of the class Cephalopoda, with the mouth and head surrounded by tentacles. Cephalopods are the most intelligent, the fastest-moving, and the largest of all animals without backbones. Examples include squid, octopus, and cuttlefish. Shells are rudimentary or absent in most cephalopods.
 
 
   
 
  chitin
complex long-chain compound, or polymer; a nitrogenous derivative of glucose. Chitin is widely found in invertebrates. It forms the exoskeleton of insects and other arthropods. It combines with protein to form a covering that can be hard and tough, as in beetles, or soft and flexible, as in caterpillars and other insect larvae. It is insoluble in water and resistant to acids, alkalis, and many organic solvents. In crustaceans such as crabs, it is impregnated with calcium carbonate for extra strength.
 
 
   
 
  chrysalis
pupa of an insect, but especially that of a butterfly or moth. It is essentially a static stage of the creature's life, when the adult insect, benefiting from the large amounts of food laid down by the actively feeding larva, is built up from the disintegrating larval tissues. The chrysalis may be exposed or within a cocoon.
 
 
   
 
  cocoon
pupa-case of many insects, especially of moths and silkworms. This outer web or ball is spun from the mouth by caterpillars before they pass into the chrysalis state.
 
 
   
 
  cold-blooded
of animals, dependent on the surrounding temperature; see poikilothermy.
 
 
   
 
  crustacean
one of the class of arthropods that includes crabs, lobsters, shrimps, woodlice, and barnacles. The external skeleton is made of protein and chitin hardened with lime. Each segment bears a pair of appendages that may be modified as sensory feelers (antennae), as mouthparts, or as swimming, walking, or grasping structures.
 
 
   
 
  D  
 
   
 
  digestive system
the organs and tissues involved in the digestion of food; in animals these consist of the mouth, stomach, intestines, and their associated glands. Birds have two additional digestive organs—the crop and gizzard. In smaller, simpler animals such as jellyfish, the digestive system is simply a cavity (coelenteron or enteric cavity) with a "mouth" into which food is taken; the digestible portion is dissolved and absorbed in this cavity, and the remains are ejected back through the mouth.
 
 

 

 

 

   
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  dinosaur
(Greek deinos "terrible," sauros "lizard") any of a group (sometimes considered as two separate orders) of extinct reptiles living between 205 million and 65 million years ago. Their closest living relations are crocodiles and birds. Many species of dinosaur evolved during the millions of years they were the dominant large land animals. Most were large (up to 27 m/90 ft), but some were as small as chickens. They disappeared 65 million years ago for reasons not fully understood, although many theories exist.
 
 
   
 
  dodo
extinct flightless bird Raphus cucullatus, order Columbiformes, formerly found on the island of Mauritius, but exterminated by early settlers around 1681. Although related to the pigeons, it was larger than a turkey, with a bulky body, rudimentary wings, and short curly tail-feathers. The bill was blackish in color, forming a horny hook at the end.
 
 
   
 
  E  
 
   
 
  ecdysis
period shedding of the exoskeleton by insects and other arthropods to allow growth. Prior to shedding, a new soft and expandable layer is first laid down underneath the existing one. The old layer then splits, the animal moves free of it, and the new layer expands and hardens.
 
 
   
 
  echolocation
method used by certain animals, notably bats, whales, and dolphins, to detect the positions of objects by using sound. The animal emits a stream of high-pitched sounds, generally at ultrasonic frequencies (beyond the range of human hearing), and listens for the returning echoes reflected off objects to determine their exact location.
 
 
   
 
  egg
in animals, the ovum, or female gamete (reproductive cell). After fertilization by a sperm cell, it begins to divide to form an embryo. Eggs may be deposited by the female (ovipary) or they may develop within her body (vivipary and ovovivipary). In the oviparous reptiles and birds, the egg is protected by a shell, and well supplied with nutrients in the form of yolk.
 
 
   
 
  embryo
early developmental stage of an animal following fertilization of an ovum (egg cell), or activation of an ovum by parthenogenesis.
 
 
   
 
  endoskeleton
the internal supporting structure of vertebrates, made up of cartilage or bone. It provides support, and acts as a system of levers to which muscles are attached to provide movement. Certain parts of the skeleton (the skull and ribs) give protection to vital body organs. Sponges are supported by a network of rigid, or semi-rigid, spiky structures called spicules.
 
 
   
 
  estivation
a state of inactivity and reduced metabolic activity, similar to hibernation, that occurs during the dry season in species such as lungfish and snails.
 
 
   
 
  ethology
comparative study of animal behavior in its natural setting. Ethology is concerned with the causal mechanisms (both the stimuli that elicit behavior and the physiological mechanisms controlling it), as well as the development of behavior, its function, and its evolutionary history.
 
 
   
 
  exoskeleton
the hardened external skeleton of insects, spiders, crabs, and other arthropods. It provides attachment for muscles and protection for the internal organs, as well as support. To permit growth it is periodically shed in a process called ecdysis.
 
 
   
 
  extinction
the complete disappearance of a species. In the past, extinctions are believed to have occurred because species were unable to adapt quickly enough to a naturally changing environment. Today, most extinctions are due to human activity.
 
 
   
 
  eye
the organ of vision. In many animal eyes, as in humans, the light is focused by the combined action of the curved cornea, the internal fluids, and the lens. The insect eye is compound—made up of many separate facets—known as ommatidia, each of which collects light and directs it separately to a receptor to build up an image. Invertebrates have much simpler eyes, with no lenses. Among mollusks, cephalopods have complex eyes similar to those of vertebrates.
 
 
   
 
  F  
 
   
 
  feather
rigid outgrowth of the outer layer of the skin of birds, made of the protein keratin. Feathers provide insulation and facilitate flight. There are several types, including long quill feathers on the wings and tail, fluffy down feathers for retaining body heat, and contour feathers covering the body. The coloring of feathers is often important in camouflage or in courtship and other displays. Feathers are normally replaced at least once a year.
 
 
   
 
  fin
in aquatic animals, flattened extension from the body that aids balance and propulsion through the water.
 
 
   
 
  fur
the hair of certain animals. Fur is an excellent insulating material. Fur such as mink is made up of a soft, thick, insulating layer called underfur and a top layer of longer, lustrous guard hairs.
 
 
   
 
  G  
 
   
 
  gastropod
any member of a very large group of mollusks, having a single shell (in a spiral or modified spiral form) and eyes on stalks, and moving on a flattened, muscular foot. Gastropods have well-developed heads and rough, scraping tongues called radulae. Some are marine, some freshwater, and others land creatures, but they all tend to live in damp places.
 
 
   
 
  gestation
in all mammals except the monotremes (platypus and spiny anteaters), the period from the time of implantation of the embryo in the uterus to birth.
 
 
   
 
  gill
the main respiratory organ of most fishes and immature amphibians, and of many aquatic invertebrates. In all types, water passes over the gills, and oxygen diffuses across the gill membranes into the circulatory system, while carbon dioxide passes from the system out into the water.
 
 
   
 
  H  
 
   
 
  heart
muscular organ that rhythmically contracts to force blood around the body of an animal with a circulatory system. Annelid worms and some other invertebrates have simple hearts consisting of thickened sections of main blood vessels that pulse regularly. An earthworm has ten such hearts. Vertebrates have one heart. A fish heart has two chambers—the thin-walled atrium (once called the auricle) that expands to receive blood, and the thick-walled ventricle that pumps it out. Amphibians and most reptiles have two atria and one ventricle; birds and mammals have two atria and two ventricles.
 
 
   
 
  herbivore
animal that feeds on green plants (or photosynthetic single-celled organisms) or their products, including seeds, fruit, and nectar. The most numerous type of herbivore is thought to be the zooplankton, tiny invertebrates in the surface waters of the oceans that feed on small photo-
 
 

 

 

 

   
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  synthetic algae. Herbivores are more numerous than other animals because their food is the most abundant. They form a vital link in the food chain between plants and carnivores.  
 
   
 
  hibernation
state of dormancy in which certain animals spend the winter. It is associated with a dramatic reduction in all metabolic processes, including body temperature, breathing, and heart rate. It is a fallacy that animals sleep throughout the winter.
 
 
   
 
  homeothermy
maintenance of a constant body temperature in endothermic (warm-blooded) animals, by the use of chemical processes to compensate for heat loss or gain when external temperatures change. Such processes include generation of heat by the breakdown of food and the contraction of muscles, and loss of heat by sweating, panting, and other means.
 
 
   
 
  hoof
horny covering that protects the sensitive parts of the foot of an animal. The possession of hooves is characteristic of the orders Artiodactyla (even-toed ungulates such as deer and cattle), and Perissodactyla (horses, tapirs, and rhinoceroses).
 
 
   
 
  horn
broad term for hardened processes on the heads of some members of order Artiodactyla: deer, antelopes, cattle, goats, and sheep; and the rhinoceroses in order Perissodactyla. They are used usually for sparring rather than serious fighting, often between members of the same species rather than against predators.
 
 
   
 
  hybrid
offspring from a cross between individuals of two different species, or two inbred lines within a species. In most cases, hybrids between species are infertile and unable to reproduce sexually.
 
 
   
 
  hydra
any of a group of freshwater polyps, belonging among the coelenterates. The body is a double-layered tube (with six to ten hollow tentacles around the mouth), 1.25 cm/0.5 in long when extended, but capable of contracting to a small knob. Usually fixed to waterweed, hydras feed on minute animals that are caught and paralyzed by stinging cells on the tentacles.
 
 
   
 
  I  
 
   
 
  imago
sexually mature stage of an insect.
 
 
   
 
  insectivore
any animal whose diet is made up largely or exclusively of insects. In particular, the name is applied to mammals of the order Insectivora, which includes the shrews, hedgehogs, moles, and tenrecs.
 
 
   
 
  instinct
behavior found in all equivalent members of a given species (for example, all the males, or all the females with young) that is presumed to be genetically determined. Examples include a male robin's tendency to attack other male robins intruding on its territory and the tendency of many female mammals to care for their offspring.
 
 
   
 
  invertebrate
animal without a backbone. The invertebrates comprise over 95% of the million or so existing animal species and include sponges, coelenterates, flatworms, nematodes, annelid worms, arthropods, mollusks, echinoderms, and primitive aquatic chordates, such as sea squirts and lancelets.
 
 
   
 
  ivory
hard white substance of which the teeth and tusks of certain mammals are made. Among the most valuable are elephants' tusks, which are of unusual hardness and density.
 
 
   
 
  K  
 
   
 
  keratin
fibrous protein found in the skin of vertebrates and also in hair, nails, claws, hooves, feathers, and the outer coating of horns.
 
 
   
 
  krill
any of several Antarctic crustaceans, the most common species being Euphausia superba. Similar to a shrimp, it is up to 5 cm/2 in long, with two antennae, five pairs of legs, seven pairs of light organs along the body, and is colored orange above and green beneath. It is one of the most abundant animals, numbering perhaps 600 trillion (million million) individuals.
 
 
   
 
  L  
 
   
 
  lactation
secretion of milk in mammals, from the mammary glands. In late pregnancy, the cells lining the lobules inside the mammary glands begin extracting substances from the blood to produce milk. The supply of milk starts shortly after birth and continues practically as long as the young continue to suckle.
 
 
   
 
  larva
stage between hatching and adulthood in those species in which the young have a different appearance and way of life from the adults. Examples include tadpoles (frogs) and caterpillars (butterflies and moths). Larvae are typical of the invertebrates, some of which (for example, shrimps) have two or more distinct larval stages. Among vertebrates, it is only the amphibians and some fishes that have a larval stage. The process whereby the larva changes into another stage, such as a pupa (chrysalis) or adult, is known as metamorphosis.
 
 
   
 
  lek
a closely spaced set of very small territories each occupied by a single male during the mating season. Leks are found in the mating systems of several ground-dwelling birds (such as grouse) and a few antelopes.
 
 
   
 
  lizard
reptile generally distinguishable from snakes, which belong to the same order, by having four legs, moveable eyelids, eardrums, and a fleshy tongue, although some lizards are legless and snakelike in appearance. There are over 3,000 species of lizard worldwide.
 
 
   
 
  M  
 
   
 
  maggot
soft, plump, limbless larva of flies, a typical example being the larva of the blowfly which is deposited as an egg on flesh.
 
 
   
 
  mammary gland
in female mammals, a milk-producing gland derived from epithelial cells underlying the skin, active only after the production of young. In all but monotremes (egglaying mammals), the mammary glands terminate in teats which aid infant suckling. The number of glands and their position vary between species.
 
 
   
 
  mammoth
extinct elephant, remains of which have been found worldwide. Some were 50% taller than modern elephants; others were much smaller.
 
 
   
 
  mastodon
any of an extinct family of mammals belonging to the elephant order. They differed from elephants and mammoths in the structure of their grinding teeth. There were numerous species, among which the American mastodon (Mastodon americanum), about 3 m/10 ft high, of the Pleistocene era, is well known.
 
 
   
 
  megapode,
or mound-builder any of a group of chickenlike birds found in the Malay archipelago and Australia. They pile up large mounds of vegetable matter, earth, and sand 4 m/
 
 

 

 

 

   
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  13 ft across, in which to deposit their eggs, then cover the eggs and leave them to be incubated by the heat produced by the rotting vegetation. There are 19 species, all large birds, 50–70 cm/20–27 in in length, with very large feet.  
 
   
 
  metamorphosis
period during the life cycle of many invertebrates, most amphibians, and some fish, during which the individual's body changes from one form to another through a major reconstitution of its tissues. For example, adult frogs are produced by metamorphosis from tadpoles, and butterflies are produced from caterpillars following metamorphosis within a pupa.
 
 
   
 
  milk
secretion of the mammary glands of female mammals, with which they suckle their young (during lactation). Over 85% is water, the remainder comprising protein, fat, lactose (a sugar), calcium, phosphorus, iron, and vitamins.
 
 
   
 
  mimicry
imitation of one species (or group of species) by another. The most common form is Batesian mimicry (named for the English naturalist H. W. Bates), where the mimic resembles a model that is poisonous or unpleasant to eat, and has aposematic, or warning, coloration; the mimic thus benefits from the fact that predators have learned to avoid the model. Hoverflies that resemble bees or wasps are an example. Appearance is usually the basis for mimicry, but calls, songs, scents, and other signals can also be mimicked.
 
 
   
 
  moa
any of a group of extinct flightless kiwi-like birds that lived in New Zealand. There were 19 species; they varied from 0.5 to 3.5 m/2 to 12 ft, with strong limbs, a long neck, and no wings. The largest species was Dinornis maximus. The last moa was killed in the 1800s.
 
 
   
 
  moth
any of a large number of mainly night-flying insects closely related to butterflies. Their wings are covered with microscopic scales. Most moths have a long sucking mouthpart (proboscis) for feeding on the nectar of flowers, but some have no functional mouthparts and rely instead upon stores of fat and other reserves built up during the caterpillar stage. At least 100,000 different species of moth are known.
 
 
   
 
  molting
periodic shedding of the hair or fur of mammals, feathers of birds, or skin of reptiles. In mammals and birds, molting is usually seasonal and is triggered by changes of day length.
 
 
   
 
  N  
 
   
 
  nest
place chosen or constructed by a bird or other animal for incubation of eggs, hibernation, and shelter. Nests vary enormously, from saucerlike hollows in the ground, such as the scrapes of hares, to large and elaborate structures, such as the 4-m/13-ft diameter mounds of the megapode birds.
 
 
   
 
  notochord
the stiff but flexible rod that lies between the gut and the nerve cord of all embryonic and larval chordates, including the vertebrates. It forms the supporting structure of the adult lancelet, but in vertebrates it is replaced by the vertebral column, or spine.
 
 
   
 
  nymph
in entomology, the immature form of insects that do not have a pupal stage; for example, grasshoppers and dragonflies. Nymphs generally resemble the adult (unlike larvae), but do not have fully formed reproductive organs or wings.
 
 
   
 
  O  
 
   
 
  omnivore
animal that feeds on both plant and animal material. Omnivores have digestive adaptations intermediate between those of herbivores and carnivores, with relatively unspecialized digestive systems and gut microorganisms that can digest a variety of foodstuffs. Omnivores include the chimpanzee, the cockroach, and the ant.
 
 
   
 
  oviparity
method of animal reproduction in which eggs are laid by the female and develop outside her body, in contrast to ovoviviparity and viviparity. It is the most common form of reproduction
 
 
   
 
  ovoviviparity
method of animal reproduction in which fertilized eggs develop within the female (unlike oviparity), and the embryo gains no nutritional substances from the female (unlike viviparity). It occurs in some invertebrates, fishes, and reptiles.
 
 
   
 
  P  
 
   
 
  parasite
organism that lives on or in another organism (called the host) and depends on it for nutrition, often at the expense of the host's welfare. Parasites that live inside the host, such as liver flukes and tapeworms, are called endoparasites; those that live on the exterior, such as fleas and lice, are called ectoparasites.
 
 
   
 
  plankton
small, often microscopic, forms of plant and animal life that live in the upper layers of fresh and salt water, and are an important source of food for larger animals. Marine plankton is concentrated in areas where rising currents bring mineral salts to the surface.
 
 
   
 
  poikilothermy
the condition in which an animal's body temperature is largely dependent on the temperature of the air or water in which it lives. It is characteristic of all animals except birds and mammals, which maintain their body temperatures by homeothermy (they are "warm-blooded").
 
 
   
 
  primate
any member of the order of mammals that includes monkeys, apes, and humans (together called anthropoids), as well as lemurs, bushbabies, lorises, and tarsiers (together called prosimians). Generally, they have forward-directed eyes, gripping hands and feet, opposable thumbs, and big toes. They tend to have nails rather than claws, with gripping pads on the ends of the digits, all adaptations to the arboreal, climbing mode of life.
 
 
   
 
  pupa
nonfeeding, largely immobile stage of some insect life cycles, in which larval tissues are broken down, and adult tissues and structures are formed. In many insects, the pupa is exarate, with the appendages (legs, antennae, wings) visible outside the pupal case; in butterflies and moths, it is called a chrysalis, and is obtect, with the appendages developing inside the case.
 
 
   
 
  R  
 
   
 
  rodent
any mammal of the worldwide order Rodentia, making up nearly half of all mammal species. They are distinguishable by, among other things, a single front pair of incisor teeth in both upper and lower jaw, which continue to grow as they are worn down. They are often subdivided into three suborders: Sciuromorpha, including primitive rodents, with squirrels as modern representatives; Myomorpha, rats and mice and their relatives; and Hystricomorpha, including the Old World and New World porcupines and guinea pigs.
 
 
   
 
  rotifer
any of the tiny invertebrates, also called "wheel animalcules," of the phylum Rotifera. Mainly freshwater, some marine, rotifers have a ring of cilia that carries food to the mouth and also provides propulsion. They are the smallest of multicellular animals—few reach 0.05 cm/0.02 in.
 
 

 

 

 

   
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  ruminant
any even-toed hoofed mammal with a rumen, the "first stomach" of its complex digestive system. Plant food is stored and fermented before being brought back to the mouth for chewing (chewing the cud) and then is swallowed to the next stomach. Ruminants include cattle, antelopes, goats, deer, and giraffes, all with a four-chambered stomach. Camels are also ruminants, but they have a three-chambered stomach.
 
 
   
 
  S  
 
   
 
  shellfish
popular name for mollusks and crustaceans, including the whelk and periwinkle, mussel, oyster, lobster, crab, and shrimp.
 
 
   
 
  skeleton
the rigid or semirigid framework that supports and gives form to an animal's body, protects its internal organs, and provides anchorage points for its muscles. The skeleton may be composed of bone and cartilage (vertebrates), chitin (arthropods), calcium carbonate (mollusks and other invertebrates), or silica (many protists).
 
 
   
 
  snake
reptile of the suborder Serpentes of the order Squamata, which also includes lizards. Snakes are characterized by an elongated limbless body and scaly skin. There are 3,000 species found in the tropical and temperate zones, but none in New Zealand, Ireland, Iceland, and near the poles.
 
 
   
 
  sperm,
or spermatozoon, the male gamete (reproductive cell) of animals. Each sperm cell has a head capsule containing a nucleus, a middle portion containing mitochondria (which provide energy), and a long tail (flagellum).
 
 
   
 
  spider
any arachnid (eight-legged animal) of the order Araneae. There are about 30,000 known species, mostly a few centimeters in size, although a few tropical forms attain great size, for example, some bird-eating spiders attain a body length of 9 cm/3.5 in. Spiders produce silk, and many spin webs to trap their prey. They are found everywhere in the world except Antarctica. Many species are found in woods and dry commons; a few are aquatic. Spiders are predators; they bite their prey, releasing a powerful toxin from poison glands which causes paralysis, together with digestive juices. They then suck out the juices and soft parts.
 
 
   
 
  spiracle
in insects, the opening of a trachea (airway), through which oxygen enters the body and carbon dioxide is expelled. In cartilaginous fishes (sharks and rays) the same name is given to a circular opening that marks the remains of the first gill slit.
 
 
   
 
  stomach
the first cavity in the digestive system of animals. In mammals it is a bag of muscle situated just below the diaphragm. Food enters it from the esophagus, is digested by the acid and enzymes secreted by the stomach lining, and then passes into the duodenum. Some plant-eating mammals have multichambered stomachs that harbor bacteria in one of the chambers to assist in the digestion of cellulose. The gizzard is part of the stomach in birds.
 
 
   
 
  T  
 
   
 
  tooth
in vertebrates, one of a set of hard, bonelike structures in the mouth, used for biting and chewing food, and in defense and aggression. Mammalian teeth have roots surrounded by cementum, which fuses them into their sockets in the jawbones. The neck of the tooth is covered by the gum, while the enamel-covered crown protrudes above the gum line.
 
 
   
 
  trilobite
any of a large class (Trilobita) of extinct, marine, invertebrate arthropods of the Palaeozoic era, with a flattened, oval body, 1–65 cm/0.4–26 in long. The hard-shelled body was divided by two deep furrows into three lobes. Some were burrowers, others were swimming and floating forms.
 
 
   
 
  tunicate
any marine chordate of the subphylum Tunicata (Urochordata), for example the sea squirt. Tunicates have transparent or translucent tunics made of cellulose. They vary in size from a few millimeters to 30 cm/1 ft in length, and are cylindrical, circular, or irregular in shape. There are more than 1,000 species.
 
 
   
 
  U  
 
   
 
  ungulate
general name for any hoofed mammal. Included are the odd-toed ungulates (perissodactyls) and the even-toed ungulates (artiodactyls), along with subungulates such as elephants.
 
 
   
 
  V  
 
   
 
  vertebrate
any animal with a backbone. The 41,000 species of vertebrates include mammals, birds, reptiles, amphibians, and fishes. They include most of the larger animals, but in terms of numbers of species are only a tiny proportion of the world's animals.
 
 
   
 
  viviparity
a method of reproduction in which the embryo develops inside the body of the female from which it gains nourishment (in contrast to oviparity and ovoviparity). Viviparity is best developed in placental mammals, but also occurs in some arthropods, fishes, amphibians, and reptiles that have placenta-like structures.
 
 
   
 
  W  
 
   
 
  warm-blooded
of animals, not dependent on the surrounding temperature; see homeothermy.
 
 
   
 
  waterfowl
any water bird, but especially any member of the family Anatidae, which consists of ducks, geese, and swans.
 
 
   
 
  whale
any marine mammal of the order Cetacea. The only mammals to have adapted to living entirely in water, they have front limbs modified into flippers and no externally visible traces of hind limbs. They have horizontal tail flukes. When they surface to breathe, the hot air they breathe out condenses to form a "spout" through the blowhole (single or double nostrils) in the top of the head. The largest whales are the baleen whales, with plates of modified mucous membrane called baleen (whalebone) in the mouth; these strain the food, mainly microscopic plankton, from the water. Baleen whales include the finback and right whales, and the blue whale, the largest animal that has ever lived, of length up to 30 m/100 ft.
 
 
   
 
  worm
any of various elongated limbless invertebrates belonging to several phyla. Worms include the flatworms, such as flukes and tapeworms; the roundworms or nematodes, such as the eelworm and the hookworm; the marine ribbon worms or nemerteans; and the segmented worms or annelids.
 
 
   
 
  Z  
 
   
 
  zoo
(abbreviation for zoological gardens) place where animals are kept in captivity. Originally created purely for visitor entertainment and education, zoos have become major centers for the breeding of endangered species of animals. The Arabian oryx has already been preserved in this way; it was captured in 1962, bred in captivity, and released again in the desert in 1972, where it has flourished.
 
 

 

 

 

   
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  Further Reading  
 
 
 
  Berenbaum, May R. Bugs in the System: Insects and Their Impact on Human Affairs (1995)  
 
 
 
  Brooke, Michael, and Birkhead, Tim (eds.) The Cambridge Encyclopedia of Ornithology (1991)  
 
 
 
  Chapman, R. F. The Insects: Structure and Function (1982)  
 
 
 
  Cheney, Dorothy L., and Seyfarth, Robert M. How Monkeys See the World (1990)  
 
 
 
  Chinery, Michael A Field Guide to the Insects of Britain and Northern Europe (1982)  
 
 
 
  Clarke, P. A. B., and Linzey, Andrew (eds.) Political Theory and Animal Rights (1990)  
 
 
 
  Dawkins, Richard The Selfish Gene (1976)  
 
 
 
  del Hoyo, Josep; Elliott, Andrew; and Sargatal, Jordi (eds.) Handbook of the Birds of the World (1992, continuing)  
 
 
 
  Diamond, Anthony Save the Birds (1987)  
 
 
 
  Gadagkar, Raghavendra Survival Strategies (1998)  
 
 
 
  Goodall, Jane In the Shadow of Man (1983)  
 
 
 
  Gould, James, and Gould, Carol Grant (eds.) Life at the Edge (1989)  
 
 
 
  Feduccia, Alan The Age of Birds (1980)  
 
 
 
  Halliday, Tim and Alder, K. The Encyclopedia of Reptiles and Amphibians (1986)  
 
 
 
  Haraway, Donna Primate Visions (1992)  
 
 
 
  Hölldobler, B., and Wilson, E. O. Journey to the Ants (1994)  
 
 
 
  Lack, David The Life of the Robin (1943)  
 
 
 
  Linzey, Andrew Animal Rights (1976)  
 
 
 
  McFarland, David (ed.) The Oxford Companion to Animal Behaviour (1981)  
 
 
 
  Maeterlink, Maurice Life of the Bee (1901)  
 
 
 
  Mead, Chris Bird Migration (1983)  
 
 
 
  Nelson, Joseph S. Fishes of the World (1976; 3rd edition 1994)  
 
 
 
  Norse, Elliott A. (ed) Global Marine Biological Diversity (1993)  
 
 
 
  Obee, Bruce, and Ellis, Graeme Guardians of the Whales–The Quest to Study Whales in the Wild (1992)  
 
 
 
  Paxton, John R., and Eschmeyer, William N. (eds.) Encyclopedia of Fishes (1994)  
 
 
 
  Richards, O. W., and Davies, R. G. Imm's General Textbook of Entomology, Volume 2 (10th edition 1977)  
 
 
 
  Ridley, Matt The Red Queen (1993)  
 
 
 
  Samways, M. J. Insect Conservation Biology (1994)  
 
 
 
  Springer, Victor G., and Gold, Joy P. Sharks in Question (1989)  
 
 
 
  Strattersfield, Alison, Crosby, Michael, et al (eds.) Endemic Bird Areas of the World (1998)  
 
 
 
  Tinbergen, Niko The Study of Instinct (1951)  
 
 
 
  Tudge, Colin Last Animals at the Zoo (1991)  
 
 
 
  von Frisch, Karl The Dance Language and Orientation of Bees (1967)  
 
 
 
  Wade, Nicholas (ed.) The Science Times Book of Fish (1998)  
 
 
 
  Waller, Geoffrey Sealife: A Complete Guide to the Marine Environment (1996)  
 
 
 
  Wells, Sue, and Hanna, Nick The Greenpeace Book of Coral Reefs (1992)  
 
 
 
  Wheeler, Alwyne Fishes of the World: An Illustrated Dictionary (1975)  
 
 
 
  Wilson, Edward O. Sociobiology (1975)