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STICKLEBACK
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STICKLEBACK , the name applied to a See also:group of small fishes (Gastrosteus) which inhabit the fresh and brackish See also:waters as well as the coasts of the temperate See also:zone of the See also:northern hemisphere. As far as the See also:European kinds are concerned, all may be met with in the brackish See also:water of certain littoral districts. The See also:majority have a compressed well-proportioned See also:body, which in the marine See also:species is of a more elongate See also:form, leading to the allied group of See also:flute-mouths (Fistulariidae), which are, in fact, gigantic marine sticklebacks. Their mouth is of moderate width, oblique, and armed with small but firmly set See also:teeth. The See also:head is almost entirely protected by hard See also:bone; even the cheeks are cuirassed by the dilated infraorbital bones. There are no scales See also:developed on any See also:part of the body, but a See also:series of hard and large scutes protects a greater or lesser portion of the sides. The first dorsal fin and the ventrals are transformed into pointed formidable spines, and joined to See also:firm bony plates of the endoskeleton. With regard to the degree in which this See also:armature is developed, not only do the species differ from each other, but almost every species shows an extraordinary amount of variation. About ten kinds may be taken to be specifically distinct. So far as is known at See also:present, all sticklebacks construct a See also:nest for the reception of the spawn, which is jealously guarded by the male until the See also:young are hatched, which event takes See also:place in from ten to eighteen days after oviposition. He also protects them for the first few days of their existence. Sticklebacks are See also:short-lived animals; they are said to reach an See also:age of only three or four years; yet their short See also:life, at least that of the See also:males, is full of excitement. During the first See also:year of their existence, before the breeding See also:season begins, they live in small companies in still pools or gently flowing See also:brooks. But with the return of the warmer season each male selects a territory, which he fiercely defends against all corners, especially against intruders of his own species and See also:sex, and to which he invites all See also:females, until the nest is filled with ova. At this See also:period he also assumes a bridal See also:dress, painted with See also:blue and red tints. The eggs are of comparatively large See also:size, one See also:female depositing from 50 to too. Gastrosteus aculeatus, See also:var. noveboracensis, Three-Spined Stickleback. Of the species known not one has so wide a See also:geographical range, and has so well been studied, as the See also:common See also:British threespined stickleback (Gastrosteus aculeatus). It is found every-where in northern and central See also:Europe, northern See also:Asia, and See also:North See also:America. The development of its scutes and spines varies exceedingly, and specimens may be found without any lateral scutes and with short spines, others with only a few scutes and moderately sized spines, and again others which possess a See also:complete See also:row of scutes from the head to the caudal fin, and in which the fin-spines are twice as See also:long and strong as in other varieties. On the whole, the smooth varieties are more numerous in See also:southern than in northern localities. This species swarms in some years in prodigious See also:numbers; in See also:Pennant's See also:time amazing shoals appeared in the See also:fens of See also:Lincolnshire every seven or eight years. No instance of a similar increase of this See also:fish has been observed in our time, and this possibly may be due to the diminished number of suitable breeding-places in consequence of the introduction of artificial drainage. This species usually constructs its nest on the bottom, excavating a hollow in which a See also:bed of grass, rootlets or See also:fibres is prepared; walls are then raised, and the whole is roofed over with the like material. The nest is an See also:inch and more in See also:diameter, with a small See also:aperture for an entrance. The ten-spined stickleback (Gastrosteus pungitius) is so called from the number of spines usually composing its first dorsal fin, which, however, may be sometimes reduced to eight or nine or increased to eleven. It is smaller than the three-spined species, rarely exceeding 2 in. in length. Its geographical range nearly coincides with that of the other species, but it is more locally distributed, and its range in northern Asia is not known. Its nest is generally placed among weeds above the bottom of the water. Breeding males are readily recognized at a distance by the intensely See also:black See also:colour of the See also:lower parts of their body. Both these species are extremely voracious. A small stickle-back kept in an See also:aquarium devoured, in five See also:hours' time, 74 newly-hatched See also:dace, which were about a See also:quarter of an inch long. Two days after it swallowed 62 and would probably have eaten as many every See also:day could they have been procured. The See also:sea-stickleback (Gastrosteus spinachia or Spinachia vulgaris) attains to a length of 7 in., and is armed with fifteen short spines on the back. It is extremely common See also:round the British coasts, but never congregates in large shoals. At suitable localities of the See also:coast which are sheltered from the waves and overgrown with seaweed, especially in See also:rock-pools, one, or two males establish themselves with their harems, and may be observed without difficulty, being quite as fearless as their fresh-water See also:cousins. Harbours and shallows covered with Zostera are likewise favourite haunts of this species, although the water may be brackish. The nest is always firmly attached to sea-See also:weed, and sometimes suspended from an over-See also:hanging frond. The materials are See also:bound together by a tough See also: Additional information and CommentsThere are no comments yet for this article.
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