Natural History: Mollusca. Philip Henry Gosse

CUTTLE-BONE.In this genus, which contains our commonest species of the Order, the body is oblong and flattened, with the side-fins extending along its whole length. The mantle is free at its front margin; the suckers are supported by horny hoops with entire edges. The internal support is shelly, and is composed of a succession of extremely delicate plates, sustained by slender columns, regularly arranged, the spaces between the plates being filled with air.

      Many of my readers are doubtless familiar with the object here represented, so frequently cast up by the waves upon our smooth sandy beaches: it is the shell of the common Cuttle-fish (Sepia officinalis). Its use is not only to give firmness to the soft and jelly-like body of the animal, but to aid it in swimming by its buoyancy; for though the material of which it is composed is stone, from the delicacy of its texture and the peculiar arrangement of the plates, the large proportion of air ​enclosed within it renders the whole lighter than water.

       CUTTLE.The Cuttle is about a foot in length, of an oblong form. Its colour is a dull, dirty white, mottled and spotted with those changing veins of fluid, already described, of a reddish brown hue. The texture of the body is soft and flabby, but, notwithstanding its unpleasing appearance, it forms a wholesome and agreeable dish wherever prejudice does not preclude its use. When well cooked the flesh is tender and digestible, bearing considerable resemblance to tripe.

I have already alluded to the inky fluid secreted in an internal reservoir within the body of the Cuttle. It is poured forth in copious quantity from a funnel-like tube beneath the mantle, and is intended as a means of concealment, and of annoyance to its pursuers. "A gallant officer who was inconsiderately collecting shells in a pair of immaculate white trowsers, came suddenly upon ​one of the naked Cephalopods snugly harboured in a recess in the rock. They looked at each other, and the Cuttle, who had his eyes about him, and knew well how to use them, upon seeing the enemy advance, took good aim, and shot so true that he covered the snowy inexpressibles with the contents of his ink-bag, and rendered them unpresentable either in drawing-room or dining-room."^[3]

      Entangled among the sea-weeds washed up on the sea-beach in the latter part of summer, we occasionally see what at first sight we are ready to take for a bunch of purple grapes. The fisherman indeed calls them sea-grapes, so close is the likeness in colour, size, and aggregation. But if we take the cluster into our hand and examine it, we shall see that their texture is leathery, or somewhat like India-rubber, that the extremity of each berry runs out to a point, and that its base springs from a fleshy cord which clings and entwines irregularly around the marine plants. These berries are the eggs of the Cuttle-fish, and if we were to open the tough skin of one, we should find either the white yolk and clear glaire, or else the infant animal, perhaps fully formed and ready to take advantage of this premature opening of his prison, by darting out, with all his organs perfected and all his wits about him.

      The parrot-like beak presents a strong exception to the general softness of this animal; it is so hard, stout, and stony, and moved by such powerful muscles, that the strong shells of bivalves and univalves are not able to resist its force: even the hard and stony limpet is dragged from its attachment, and crushed to pieces in these powerful mandibles.

      1 ↑ Edinb. New Phil. Journ. XVII. 319.

      2 ↑ Whaling Voyage round the Globe.

      3 ↑ Penny Cyclop. art. Sepiadæ.

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CLASS II. PTEROPODA.

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      (Fin-footed Mollusks.)

      This is a very small Class, comprising a few species of curious structure. They are all of diminutive size, and all swim in the open ocean, rarely approaching the shore, except when washed thither by accident. They are all characterised by having a membranous expansion, resembling a large fin, on each side of the head. By means of these organs, the little Pteropod rows itself about in the open sea perpetually; being unfurnished with any means of crawling, or of affixing itself to any solid body. Some of these animals, as the genera Hyalæa (a) and Cleodora (b), for example, have the body enclosed in a shell of elegant form, and of

      GLASS SHELLS.

      a texture resembling the thinnest glass, for delicacy and transparency. The Cleodora pyramidata, one of the species of the latter genus, is of extreme delicacy and beauty. The shell is glassy and colourless; ​ very fragile; nearly in the form of a triangular pyramid; with an aperture at its base, from which proceeds a long and slender glassy spine; and a similar spine projects from each side of the middle of the shell. The hinder part of the animal is globular and pellucid, and in the dark vividly luminous, presenting a singularly striking appearance, as it shines through its perfectly transparent lantern. Both of these are found floating in great numbers on the surface of the tropical sea.

      Others are entirely destitute of a shelly covering, as is that little species which occurs in enormous profusion in the Arctic Seas, and which we now proceed to describe.

Genus Clio.

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      ("Whale-food.")

      These little creatures have an oblong membranous body, without a mantle; a head formed of two rounded lobes, each of which is furnished with three long tentacles, capable of being withdrawn into a fold of skin, or protruded at pleasure. The mouth, which is terminal, has two small fleshy lips; and two eyes, of elaborate structure, are placed at the back of the neck.

      The species best known is that which is commonly called by our northern voyagers, Whale-food (Clio borealis). Though not more than an inch in length, it occurs in such countless millions as to form the principal part of the nourishment required by the most gigantic of living creatures. The Clio bears some slight resemblance to a butterfly just emerged from the chrysalis, before the wings are ​expanded. Near the head there is on each side a large fin or wing, by the motions of which it changes its place. CLIO. These motions are amusing; and as the little creatures are so abundant, they make the dreary sea quite alive with their gambols as they dance merrily along. In swimming, the Clio brings the tips of its fins almost into contact, first on one side, then on the other. In calm weather they rise to the surface in myriads, for the purpose of breathing; but scarcely have they reached it before they again descend into the deep. Mr. Scoresby kept several of them alive in a glass of sea-water for about a month, when they gradually wasted away and died. The head of one of these little creatures exhibits a most astonishing display of the wisdom of God in creation. Around the mouth are placed six tentacles, each of which is covered with about three thousand red specks, which are seen by the microscope to be transparent cylinders, each containing about twenty little suckers, capable of being thrust out, and adapted for seizing and holding their minute prey.

      Thus, therefore, there will be three hundred and sixty thousand of these microscopic suckers upon the head of one Clio: an apparatus for prehension perhaps unequalled in the creation.