File:Ocean wonders- a companion for the seaside (1879) (14579699038).jpg

Identifier: oceanwonderscomp00damo (find matches)
Title: Ocean wonders: a companion for the seaside
Year: 1879 (1870s)
Authors: Damon, William Emerson, 1838-
Subjects: Marine animals Aquariums
Publisher: New York, D. Appleton and company
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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e,bivalve, and nfiultivalve, according as they have one, two, ormore shell-plates; and, finally, into the gregarious and thesolitary. These last are considered the veritable represent-atives of this immense class of marine animals, which in-cludes almost every aquatic existence between a zoophyteand a fish. First, perhaps, it will be best to explain the process ofshell-making; for, although the shell is apparently only thehouse in which the animal lives, it is equally true that if youturn him out-of-doors he will die. The connection between 1 For illustration of the hermit-crab see page 14. MOLLUSKS: THE BORING PHOLAS, TEREDO, ETC. 83 the inhabitant and its shell is a vital one. All these soft-bodied creatures are provided with a tough, leathery, tena-cious sort of skin, the coriitm, which is commonly called itsmantle from the looseness with which it covers the body;and it is from this mantle, which is a vital tissue, that issecreted the calcareous, earthy, horny, and sometimes glassy
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Otstees, showing Different Stages of Growth. matter which forms the shell. True, the embryo, while yetin the egg, shows a rudimentary shell, but this must neces-sarily be extended if it is to protect the growing and adultanimal, which, unlike the Crustacea is not allowed to cast offits old coat and procure a new one. This secretion from the 84 THE OCEAN. mantle proceeds continually until the animal has attained itsadult size, when it appears to be passive, unless called uponto repair injuries, when its activity is again apparent. The curious varieties in shape which we see especially inthe univalve shells, many of which are knobbed, ridged, oradorned with long spines, are all the result of the shape ofthe animal; every inequality upon the shell showing a ridgeor protuberance upon the underlying skin; and the longspines equally indicate the projections which the animal hasthrown out, like so many arms, within its mantle. In manyshelled mollusks this mantle appears to have been interwov

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