Shell (zoology)

“ When live shells, as they are called, that is having the living fish in them, are obtained, the best plan is to place them in spirits of wine, this at once deprives the inhabitant of life, without injuring the shell, which should then be placed in hot water for a time, the body of the mollusk is thus rendered firm, and may be removed by means of some pointed instrument; care should be taken to leave no portion of animal matter within, or after a while it will become putrid and give out a stain, which will show through and injure the delicate markings of the shell ”

“ Most usually he walks about at the bottom of the sea on his long arms, something like the Cuttle-fish, feeding on the marine vegetation; the shell is then uppermost; if we could look inside of it we should see numerous little chambers or cells, the larger and outermost of which only are inhabited by the mollusk, the others being filled with air render the whole light and buoyant. ”

“ Specimens.—The first thing that the amateur needs to learn about a shell is that it may be living or dead. As a general thing, what is technically called a "dead" shell is worthless in a cabinet. A live shell is one which has been collected with a living mollusc in it, and then duly cleaned, preserving all its beautiful colors. ”

“ The color-patterns of the shell vary to a wonderful degree. The young shell has a thin epidermis, a sharp lip to the aperture and a more or less prominent spire, the rolled over and toothed lip and polished surface not being acquired until fully adult. No more beautiful sight can be imagined than one of these gorgeous animals, as seen through the clear water, crawling over the sandy bottom or on the branch of some coral. ”

“ The popular names of ‘shells,’ ‘shell-fish,’ and the like, as commonly applied to the Mollusca, the intrinsic beauty and grace of the shells themselves, resulting in the passion for their collection, their durability and ease of preservation, as compared with the non-testaceous portion,—all these considerations tend to unduly exalt the value of the shell as part of the organism as a whole, and to obscure the truth that the shell is by no means the most important of the organs. ”

“ We next notice that these shells are precisely similar to those still found with living occupants in the river below, only they are no longer of a brownish colour, but owing to the loss of the animal matter of the shell have an earthy, dirty-white appearance. To carry these home they should be packed in bran in one of your tins with a note as follows made on a piece of paper and placed just inside—"Sand in gravel: topmost bed —— pit, August 2nd, 188-." Then if you are not able to work them out at once on reaching home, you will not forget whence they came. ”

“ This substance is the production of the animal inhabiting the shell; it is uniformly observed in some species, and not at all in others. Shells with a rugged or uneven surface have almost always this epidermis. In some it is strong, laminated, velvety, fibrous, or rough, often beset with long hairs, and in others very thin, smooth, and pellucid, and admits the colours of the shell to shine through it. In some species it is so dusky that it entirely obscures the beautiful colouring of the shell beneath. ”

“ The shell is shaped something like that of a whelk, but is very smooth and porcelain-like, and is generally white, ornamented with several coloured bands. It is, however, one of the most variable of shells, differing not only in colour but in form. It always inhabits the belt of the shore between tide-marks, and preys upon other Molluscs, such as the mussel and periwinkle, literally licking them to pieces with its long riband tongue. ”

“ The outside of the shell presents us with some curious features; the zoologist's study leading him thus to carefully note points which an ordinary observer would hardly deem worthy his attention. When we examine the outer surface of the shell, we find it to be thickly studded over with little rounded knobs or 'tubercles,' which are, if anything, most numerous on those parts or rows of plates which are not perforated. And if we carefully study one of the spines we shall find that it is hollowed out or is concave at its base. ”

“ Among the shell-bearing molluscous animals, the little shell which contains the creature in its youngest stages remains ever after as an integral part of the outer calcareous case. As the inhabitant grows, it continues to add band after band to the outer edge of the shell, each of which, whilst preserving the general symmetry and proportions of the whole structure, increases its dimensions in every way. ”

“ The arrangement of a collection of Shells is a mere matter of taste, much depending on the space that can be afforded to it. We who lead a somewhat nomadic life, prefer keeping the smaller species in small pill boxes, which can be purchased in nests at a trifling cost, the name of each species being carefully recorded on the lid; but a pair of each shell arranged on a cardboard, with the operculum glued down alongside, facilitates easy classification and subsequent examination. ”

“ They creep through the mud and sand of the bottom by means of a fleshy foot. A current of water is drawn through a tube and is strained through the plate-like gills; it then passes into a chamber in the body and out by another tube. The food consists of minute animals and organic matter in the water. This is separated by straining the water through the gills, and is carried to the mouth by the movement of small hair-like projections or cilia. The shell is secreted by glands in the mouth, which covers the body, and is enlarged by rings as the animal grows. ”

“ FORNICATED. Arched or vaulted, as the exfoliations on the costæ of Tridacna Elongata, fig. 157.
FOSSIL SHELL. A shell is considered to be in a fossil state when, the soft parts having ceased to exist, it is deprived of all its animal juices, has lost all, or nearly all its natural colour, and is thus changed in its chemical composition, when little or nothing is left but a mere bone, which is embedded in a sedimentary deposit. ”

“ The transitions of these shells, it must be confessed are so various as to render it extremely difficult, if not unsafe, to determine where one species ends and another commences, the difference in the colours affords no sufficient data, neither is the form of the shell, nor the height of the spire so uniformly certain as to constitute a precise criterion. ”

“ We may always know the different species by the forms and patterns of the shells in which they live. Some have very regular shells and prettily marked. These are usually rounded or arched on one side and flat on the other.
When you are looking for various microscopic objects in pond water you will often see these tiny shells [90] among the sediment on your slides, and if you will patiently wait a few moments you will soon see delicate, transparent arms slowly pushing out on every side like cautious feelers. (Figure 2, Amœba in Shell.—Carpenter, p. 445.) ”

“ Many a living shell has an epidermis, the same as an animal, while a dead shell has none.
When shells are obtainable, who can resist the impulse to gather them? The man, woman, or child who is proof against the seductive powers of the beautiful and many-colored shells of the seashore "is fit for treason, stratagems, and spoils." Next to the pleasure of collecting shells one's self is that of witnessing the keen delight of children and ladies in gathering these beautiful treasures of the sea. ”

“ The shelly or membranaceous plate with which some of the animals enclose the aperture of their shells, during the wintry part of the year, for the purpose of protecting them while in a torpid state, and which they get rid of by dissolving the edges, when preparing to emerge from their temporary retirement, must not be considered as the operculum, as it does not belong to or form part of either the animal or its shell, but is produced for the occasion by a secretion of the animal, being deposited in a soft state and subsequently hardening. ”

“ Using the precious gift of observation, we have found our shells; at home we exercise the other gifts of comparison and order, in the preparation and arrangement of our collection. A dash of quite boiling water kills instantaneously any molluscs whose shells we want to preserve, and then the body is extracted after the fashion observed with regard to winkles at tea. Be careful to get out all the body of the animal, and [Pg 20] then it is well to wash out any slime or particles by directing a fine but strong jet of cold water into the shell. ”

“ This appears to be of a pale horn-colour, and destitute of any markings; but as soon as the animal enters upon an independent state of existence, it begins to assume its distinctive shape and colour, gradually increasing with the growth of its living tenant, and becoming more and more decidedly marked, until it attains its full perfection of testacean development. Thus the age of some [vi] shell-fish can be at once determined by the peculiar conformation and markings of the shell. ”

“ Shells appear to be used occasionally by other species besides man. Oyster-catchers at breeding time prepare a number of imitation nests in the gravel on the spit of land where they build, putting bits of white shell in them to represent eggs. ”

“ Well, because this is a hobby and science that spans the world. Englishmen, Frenchmen, Greeks and Indians all have their own local names for shells. But scientists everywhere give things in nature Latin names. Shells of the same sort carry the same Latin label on every beach in every sea. Much of the fascination of shell collecting is learning these names and how they were derived. . . for shells have been named for almost everything. We can't catalog 100,000 species here, but let's call off the names of a few of the interesting specimens you might come across. ”

“ The shell-bearing mollusca are proverbial for their beauty, but it is essential to bear in mind that the shell does not bear the same relation to the mollusc that the "shell" of a lobster does to that animal. The lobster's shell is part of its living body; it is a true exo-skeleton, whereas the shell of a mollusc is a more extraneous structure—a house built by the creature. We ought, on our view, to find no more relation between the decoration of a shell and the structure of its occupant, than we do in the decoration of a human dwelling-house to the tenant. ”

“ Suppose that we begin our examination by looking at the hard case or 'shell' in which the soft parts of the animal are inclosed. We find on referring to the development of the animal, that this 'shell' actually represents the hardened skin of the animal, and that viewed in this light, it closely corresponds to the shell of the lobster or crab. The shell is flattened at each pole, and we can readily perceive that it is composed of rows of little limy plates, which are disposed in a regular manner from pole to pole, or after the fashion of the meridian lines on a globe. ”

“ The smaller figure in the lower part of our plate is a representation of the same species in its usual form, and appears clothed or covered with the thick filmy epidermis, of a brown colour, with which the shell is naturally covered when in a living state. From this figure it will be perceived that the direction of the spiral wreath or whorls in the larger shell is exactly reversed, and that the mouth or aperture of the shell, which in the smaller figure appears on the right side, is seen in the reversed shell on the left. ”

“ Not only is the interior of the shell made lustrous and beautiful, but this tendency is exerted toward all objects that come in contact with the soft body of the mollusk, either by intrusion simply within the shell, or deeply within the organs and tissues of the animal itself. ”

“ This species is interesting from the changes of figure which it undergoes in its progress from youth to maturity. While young the shell is simple, with no trace of the expanded lip; and it is only at mature age, and rather suddenly, that the shell makes its remarkable growth into these far-projecting points and angles, the augmented thickness of which is, moreover, at least equally conspicuous with the expanse. ”

“ The shell of this animal is secreted by the female only, as a case or cradle for the eggs, and is not a shell to protect the animal. In geological times there were huge chambered shells inhabited by animals like the nautilus. ”

“ The “Worm-shells” (Vermetidæ) are a very peculiar family. Their shells can scarcely be distinguished from the shelly tubes which are formed by certain species of marine worms, Serpula, &c. They are free and spiral in early life, but afterwards become distorted and generally attached to rocks, stones, &c. A foot for walking purposes therefore would be of no use; consequently it is more or less obsolete, serving only as a support to the operculum.
Case 48. The “Screw-shells” (Turritellidæ) have elongate tapering shells; about 100 recent and 200 fossil species are known. ”

“ Man in his most primitive condition must have resorted to the sea-shore for the food which it affords. Weapons or other appliances were not necessary in the capture of mollusks; a stone to break the shell, or one of the massive valves of the shells themselves, sufficed for all purposes.
The shells of mollusks probably came into use as utensils at a very early date, and mutually with products of the vegetable world afforded natural vessels for food and water. ”