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CEPHALOPODA

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Originally appearing in Volume V07, Page 675 of the 1911 Encyclopedia Britannica.
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CEPHALOPODA . In the See also:

family Cheiroteuthidae many of the See also:species occur at abyssal depths of the ocean, and exhibit curious modifications of structure. In Cheiroteuthis itself the tentacular arms are very See also:long and slender, and are not capable of retraction into pockets. In several species of this genus the suckers are no longer See also:organs of See also:adhesion, but are See also:simple cups containing a network of filaments resembling a fishing See also:net. In Histioteuthis and Histiopsis, as in some Octopods, the six dorsal arms are more or less completely See also:united by a See also:web, which also probably serves for capturing See also:fish. In these two genera and in Calliteuthis the skin bears luminous organs. Cheiroteuthis has been taken at 2600 fms., Calliteuthis at 2200, Histiopsis at nearly 2000. Bathyteuthis, placed in the same family as Ommatostrephes, has been taken at 1700 fms. The Cranchiidae are remarkable for their small See also:size, the shortness of the See also:ordinary arms, and the protuberance of the eyes, which in Taonius are actually on the ends of stalk-like outgrowths of the See also:body. Cranchia is a deep-See also:sea See also:form taken at 1700 fms. Its body is See also:pear-shaped, swollen posteriorly and quite narrow at the See also:neck. Spirula is distinguished from all other existing Cephalopods by the structure of its coiled See also:shell, which in many respects resembles those of the See also:extinct See also:Ammonites, and is not completely See also:internal.

In the structure of the body the See also:

animal is a true cuttlefish in the sense in which the See also:term is here used, having ten arms and a perforated cornea. Three species are distinguished, and their empty shells occur abundantly on the shores of the tropical regions of the See also:Atlantic, Pacific and See also:Indian Oceans. In See also:German the shells are known from their shape as Posthornchen. They are See also:common on the shores of the See also:Azores. But the animal has very rarely been obtained; only a few specimens occur in museum collections. One specimen was taken by the " Challenger " in a deep-sea trawl, at a See also:depth between 300 and 400 fathoms off See also:Banda Neira in the Molluccas. Dr Willemoes Suhm, in describing the See also:capture, stated that the specimen seemed to have been in the See also:stomach of a fish, as its See also:surface was slightly digested, and he thought it must have habits of concealment which usually prevent its capture, and that it was secured on this occasion only by the capture of the fish which had swallowed it. The fact that the shells are washed ashore in such large See also:numbers is not fully explained. Possibly when freed from the animal the See also:air in the See also:chambers of the shell causes it to See also:float, and in that See also:case it would naturally be sooner or later washed ashore. (J. T.

End of Article: CEPHALOPODA

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