Mollusk

“ 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. ”

“ In passing from the mollusk to the fish to get thence to the higher vertebrates, she turned aside in another direction toward a class of animals which rises far above mollusks, but which leads to nothing beyond. ”

“ Which belonging to that division of Natural History called the Mollusca, from the Latin Mollis—soft; these Molluscous animals, then, are animals having a soft body, and no internal skeleton. You may be quite sure that a Mollusk will never break its bones, because it has none to break; it has a shell, however, which may be broken, at least in some cases, for all Mollusks have not snug habitations of the kind; but wander about the watery or earthy world in which they live, quite naked ”

“ and a mollusk is a cheap edition with a suppression of the costlier illustrations, designed for dingy circulation, for shelving in an oyster-bank or among the sea-weed. ”

“ From the oyster to the snail we have passed, step by step, along successive stages of one-sided over-development. The facts have shown that a bivalve mollusk could not have descended from a univalve. As all mollusks in early life have the axis of the body straight, and the parts symmetrically arranged on either side, we may infer that bilateral symmetry characterized the remote ancestors of the molluscan type. Now, while a mollusk is bisymmetrical or nearly so, if the mantle secretes a shell it must be in in two parts, or, as in Chiton, in many parts. ”

“ Moreover, this soft fleshy part of the creature is specially adapted to the particular requirements of the creature by having its lateral appendages—i. e. appendages which in other crustacea perform the function of legs—modified so as to act as claspers to the inside of the mollusk-shell; while the tail-end of the part in question is twisted into the form of a spiral, which fits into the spiral of the mollusk-shell. ”

“ If the observations of recent embryologists are to be credited, many mollusks and molluscoidea exhibit a similar evolution. At any rate, even in undoubted mollusca, the elements of their segmentarian origin are abundantly visible.
If we take the genus arca, for instance, as a typical mollusk, it is easy to follow the segments of which it is composed. Each half of this bivalve has its own organization, as complete as in any segment of any annulosa. Each has its own heart, its own nerve-ganglia and branches, its own aërating apparatus and systemic circulation, such as it is. ”

“ The rounding action of the mollusk is clearly shown in these excrescences, as the borer is not simply covered and levelled with the shell, but the slight elevation above the level of the lining receives a continuity of concentric deposits which finally raise it very considerably above the surface and separate it in construction from the lining to which it is attached. ”

“ 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. ”

“ A more beautiful example of a phosphorescent mollusk is presented by a sea-slug called Phyllirhoë bucephala. This is a creature of from one and a half to two inches in length, without a shell in the adult stage, and without even gills. It breathes only by the general surface of the body. ”

“ All these sea animals come from eggs, all different according to species, but all laid in measureless abundance—sometimes released into the open sea, sometimes protected in homemade nests, sometimes encased in capsules strung like beads. Hatched, most baby mollusks swim freely for a while, their tiny, transparent bodies almost invisible to the naked eye. ”

“ In the Mollusk family—another form of reversion from the primitive longitudinal or three-axed form—the conditions of existence necessitate other motive organs. This family of animals, instead of clothing itself in a dermal armor like the Echinoderms, produces a limy covering, a movable house to which it is not anatomically connected, and which principally differs from the stone mansion of the polyp in being movable. Within this house the mollusk preserves his three axed form ”

“ General characteristics—Mollusks, a numerous branch of the animal kingdom, are so called from the softness of their bodies, which usually have no internal skeleton or framework to support them. They are covered with a tough, muscular skin, and generally protected by a shell. ”

“ No, it is a reality in the service of life, a method of construction often employed by animals in their architecture. The Mollusk never makes its shell without reference to the scientific curve. The first-born of the species knew it and put it into practice ”

“ After I had learned a great many interesting things about the life and habits of the children of the sea—how in the midst of dashing waves the little polyps build the beautiful coral isles of the Pacific, and the foraminifera have made the chalk-hills of many a land—my teacher read me "The Chambered Nautilus," and showed me that the shell-building process of the mollusks is symbolical of the development of the mind. ”

“ Hence it is more than probable that the mussel, headless and inclosed in its shell and possessing relatively little interest in the affairs of the outer world, is an example of a degenerated type of mollusks. ”

“ Nothing is more curious than to see, under the microscope, these little mollusks travel in a drop of water, in vast numbers, mutually avoiding one another, crossing each other's track in every direction, with a wonderful rapidity, never touching, and never meeting. ”

“ The women and children on all these islands are accustomed to gather mollusks at every low tide for food, and whenever any particularly rare or beautiful shell is found, it is always saved; and it was for this reason that I was always confident that I could obtain some valuable [176] specimens in every village. ”

“ THE rock shells or murices are among the most beautiful and interesting of all the mollusks or shell fish, and are a favorite among collectors. Their peculiar spiny shells and brilliant colors caused them to be among the first mollusks studied by naturalists and we find them, therefore, described in the earliest works on natural history. ”

“ Those animals which subsist wholly on liquids or on minute particles require, of course, no masticating organs. Of the first class, are most parasites, the butterflies and some hummingbirds; and, of the second, bivalve mollusks and the whalebone whale. The little seachin is remarkable as the first animal, and below mollusks and articulates the only animal, possessing any organs for mastication. ”

“ Birds have early learned to take clams or mussels in their beaks or claws at low tide and carry them out of the reach of the water, so that at the death of the mollusk, the relaxation of the adductor muscle would permit the shell to spring open and afford easy access to the inmate. ”

“ In most cases the mollusks secrete from a larval gland an external shell which serves as skeleton and defensive armor; are bisexual and produce eggs, or if monœcious are never self-fertilizing. They possess a heart, and blood circulation (usually colorless) ; breathe in the water by means of gills, or, in the air, by a primitive kind of lung; have a nervous system and senses in some cases of a high order; the organs are normally paired, and protected by a general covering integument called the "mantle" ”

“ Their mode of diffusion.—Notwithstanding the proverbially slow motion of snails and mollusks in general, and although many aquatic species adhere constantly to the same rock for their whole lives, they are by no means destitute of provision for disseminating themselves rapidly over a wide area. "Some Mollusca," says Professor E. Forbes, "migrate in their larva state, for all of them undergo a metamorphosis either in the egg or out of the egg. ”

“ I have collected and obtained nearly fifty specimens; they present two varieties, the one contracted and narrow, the other broader and deeper; this difference is probably sexual; the wide and deep shells may be the females; for in the living American Uniones the same characters are observed. Some examples are remarkably well preserved; the ligament remaining in a carbonized state, and the body of the mollusk in the condition of molluskite; even a tint of the original tawny reddish colour of the shell is present. ”

“ The whole development of the mollusks, from the lowest bivalve to the highest univalve form, has tended to the production of head-limbs, and a compact, bag-like body. In their naked state their evolution is limited by this hereditary constitution. Two modes of motion are possessed, the swimming and the creeping. For use in the first there is a fin-like expansion of the body, which enables them 16 move with much rapidity, while backward motion is gained by expulsion of water from between the arm-membranes. ”

“ Yet such large Mollusks might have perished without leaving any remains recognisable in the rocks, except what may be termed their hand-writing on clay. A few small examples of the shell-bearing species of these highest Mollusks, however, appear in the Cambrian, and in the succeeding ages they become very abundant and attain to large dimensions, again dwindling toward modern times. ”

“ Describe the various types of eyes found in mollusks, and their location. Describe the tongue or lingual ribbon of the snail, and its use. What is the operculum of snails? its use? Physiology. Describe the circulation of water through the siphons and mantle cavity of a clam. How is it caused? What three uses has it? What are the principal facts about the development of fresh-water clams? Describe the circulation of blood in a clam. What various methods of locomotion are found among mollusca? Economics. ”

“ Most shells of interest to the collector are found in the sea— but not all. Living forest mollusks have been found 18,000 feet high in the Himalayas. And in this country a great variety of mollusks live in rivers, ponds, and even hot springs. Several species are peculiar to the Nile River. Also, species of mollusks live on land—for example the common garden snail.
Wherever you go, be it the South Seas, a mountain lake, or the shoals off the Gulf Coast, you'll find shells to collect and opportunities to expand your hobby. ”

“ It has been a matter of dispute with naturalists whether the testaceous mollusks have shells at all before they issue from the egg, and the main evidence favours the opinion that, generally speaking, they do possess what may be considered as a kind of pattern or model of the habitation which they are to build. ”

“ Beneath the loam which has covered them there are found the shells of edible mollusks and other relics of food, implements, ornaments and vessels, of stone, clay, and bone. Sometimes it happens that natural superposed accumulations will mark them off in layers, and distinguish the usages of successive periods. ”

“ A. S. Hardy, to the beauty and wonderful structure of mollusks and the habitations they construct for themselves. The characters in a simple story wander along the seashore gathering shells, or find them in their aquarium and converse freely about them—their forms, colors, peculiarities of structure, and the animals that inhabit them—under the guidance of one who has some scientific knowledge of them. ”

“ The lowest of the mollusks are the snails, and from these humble tenants of our ponds and shores sprang the headless bivalves and the giant jawed cuttles. The mollusks were for a long time after their development the mailed monarchs of the sea, and shared with the worms the dominion of the primordial waters. But after the development of the more active arthropods, especially the crustaceans, the less agile worms and mollusks rapidly declined. Existing worms and mollusks are remnants of once powerful and populous races. ”

“ The second class embraces the mollusks, or animals inhabiting shells. They are destitute of a spinal marrow, and for the most part their muscles are attached to the external covering, called the shell, although this shell is sometimes internal. ”

“ Mollusks in particular, like oysters and mussels, lead very monotonous and uneventful lives, only varied as a rule by the welcome change of being cut out of their shells and eaten alive; and their powers of living without food under adverse circumstances are really very remarkable. Freshwater snails and mussels, in cold weather, bury themselves in the mud of ponds or rivers; and land-snails hide themselves in the ground or under moss and leaves. ”

“ Watching from a concealed position, we could see them strut unconcernedly about, flicking their tails over their backs and jerking their necks and picking up the tiny mollusks and insects that were so abundant. ”

“ But the highest of mollusks, the cephalopods, or devil-fishes, are active and muscular creatures—the most powerful of invertebrates. They have accessory hearts to accelerate the flow of blood through the gills, which are large and plumose, and contained in a cavity. ”

“ These shells cover in patches the surface of exposed rocks, drift wood, and any other substance. Some of the mollusks affix themselves to the bodies of Whales, others form a lodgment in the hollows of corals and sponges. Once fixed they remain so during life, taking their chance of such suitable food as may come within their limited sphere of action. ”