Shark tooth

“ The system of toothing is very complicated. Not only are the sides as well as the edges of the saws toothed, but each tooth is furnished with smaller teeth, after the fashion of the shark’s wonderfully effective cutting apparatus. These subsidiary teeth vary greatly in shape and size according to the species, and in some cases each tooth is quite a complicated structure. In Trichiosoma lucorum, for example, a bee-like insect, very common upon hawthorn, the teeth are extremely beautiful. ”

“ Still more prized than the tooth itself is an imitation of it in pellucid jade. The native carver contrives to imitate his model wonderfully well, giving the peculiar curves of a shark’s tooth with singular exactness. Such an ornament as this is exceedingly scarce, and is only to be seen in the ears of the very greatest chiefs. Anything seems to serve as an earring, and it is not uncommon to see natives of either sex wearing in their ears a brass button, a key, a button-hook, or even a pipe.
There is very little variety in the mode of dressing the hair, especially among women. ”

“ Fossil Teeth of Sharks. Chalk. Lewes.
Lamna elegans. Lign. 193, fig. 6.—The fishes of the genus Lamna (to which the recent shark called the Porbeagle belongs) have teeth with smooth trenchant edges, and a small sharp denticle (little tooth) on each side the base, as in the fossil, Lign. 193, fig. 6. The specimen, fig. 2, although devoid of denticles, probably belongs to the same genus, for reasons already explained. Several species abound in the Chalk; and they are associated with teeth, which are relatively wider and shorter, and have large compressed denticles ”

“ With respect to such teeth having fangs, those of most species have merely rudiments of them, excepting the squalus cornubicus, or porbeagle shark, which has two distinct fangs to every tooth, and they may be seen in the second and third, as well as in the first rows. The posterior rows having their points turned backwards, prevent their prey, when seized, from escaping. The teeth of the shark are used by the Polynesian natives, fixed in rows, as knives. ”

“ The implement they usually employ is a shark’s tooth, which is about as well adapted to the purpose as a one-pronged fork for pitching hay. No wonder, then, that the acute Narmonee perceived the advantage my razor possessed over the usual implement. ”

“ When the throat of the animal is open we see beyond the lips, which are straight and of the consistence of leather, certain plates of teeth, which are triangular, dentate, and white as ivory. If the shark is an adult it has in the upper as in the lower jaw six rows of these murderous arms, an arsenal ready to tear and rend its victim. These teeth take different motions according to the will of the animal, and obedient to the muscles round their base, by means of which it can erect or retract its various rows of teeth ”

“ But the sharks grow several rows of teeth at once, starting them inside the mouth and letting them slide over the jaw in the skin. These are not real teeth set in the bone, but only a sort of skin teeth; and the shark grows them by the dozen, new ones as fast as the old drop out. The snakes do much the same thing with their poison fangs, and keep always at least one new pair folded down behind the old ones, ready when these get pulled out. But snakes and sharks don’t chew with their teeth, they only bite with them. ”

“ In the chimæra the mandible is articulated directly with the skull, the hyomandibular and quadrate elements being fused with the cranium. The skull in such case is said to be autostylic, that is, with self-attached mandible. In the shark it is said to be hyostylic, the hyomandibular intervening. The upper jaw in the shark consists not of maxillary and premaxillary but of palatine elements, and the two halves of the lower jaw are representatives of Meckel's cartilage, which is the cartilaginous centre of the dentary bone in the bony fishes. ”

“ Günther classifies this very queer fish as Rhinodon typicus. Sharks of the size I have mentioned as abounding in the South Pacific have often seven rows of teeth ranked behind each other. Only the first row were erect, the others lay flat as if ready to replace a sudden loss of those in use. But, after watching their operations upon pieces of “kreng,” I am bound to say that swallowing a man whole, even by the largest of them, appears to me an utterly impossible feat.
Another peculiarity of the shark is that their colossal bodies are built upon a framework of cartilage, not bone. ”

“ The mouth of these and all the other numerous extinct species of Sharks in the family of Cestracionts, was lined with a pavement of similar powerful teeth, forming a most efficient apparatus, for crushing the shells of Crustacea and Conchifera, which probably formed their principal food. The surfaces of the Enamel are often worn away, like that at Pl. 27 e . fig. 3. The strength and efficacy of these teeth, viewed as Instruments for crushing shells, is very remarkable. Beneath the Enamel, the body of each tooth is composed of a strong mass of bone. ”

“ And they are so, simply because a very large experience justifies us in believing that teeth of this particular form and structure are invariably associated with the peculiar organisation of sharks, and are never found in connection with other organisms. Why this should be we are not at present in a position even to imagine; we must take the fact as an empirical law of animal morphology, the reason of which may possibly be one day found in the history of the evolution of the shark tribe, but for which it is hopeless to seek for an explanation in ordinary physiological reasonings. ”

“ The blade of the axe, guided with an unswerving arm, fell right upon the snout of the shark, just midway between its nostrils, cleaving the cartilaginous flesh to the depth of several inches, and laying it open to the bones.
There could not have been chosen a more vital part upon which to inflict a wound; for, huge as is the white shark, and strong and vigorous as are all animals of this ferocious family, a single blow upon the nose with a handspike or even a billet of wood, if laid on with a heavy hand, will suffice to put an end to their predatory courses. ”

“ The captain seized a gun, shot the fish in a sensitive part, which then cast out the sailor into the sea, who was taken up, amazed and terrified, but little hurt.
"Every one knows that the shark is a most voracious creature. Its teeth are only incisive. It has no power of holding. It can snap and sever limbs, or trunk, or head, sheer and certainly as though its jaws were a guillotine. But in that case it secures only what is within the jaws. The rest is apt to be lost. Its habit, therefore, is to swallow the prey alive, that it may lose nothing. ”

“ The medium in which fishes live and the hard and almost indestructible nature of some portions of their skeleton, as their teeth, spines, and scales, would lead us to anticipate their frequent occurrence in the sedimentary rocks; but inasmuch as the soft parts of the animal are liable to speedy decomposition, the remains of fish must often exist in a fragmentary and scattered condition. Thus the teeth in the shark, the spine defense in the stingray, and the scales in the bony pike would survive the total destruction of the cartilaginous skeleton as well as the soft portions. ”

“ Thus in Cestracion and many extinct sharks, such as Acrodus, while the median teeth are sharp, the lateral teeth are more or less flattened and adapted for crushing. In various species belonging to the genus Raia the teeth of the male are sharp, while those of the female are blunt. A very specialised dentition is met with in the Eagle-rays (Myliobatidae) , in which the jaws are armed with flattened angular tooth-plates, arranged in seven rows, forming a compact pavement ”

“ There are six or seven branchial arches, and in the typical forms (not in Chlamydoselachus) the palato-quadrate or upper jaw articulates with the postorbital region of the skull. The teeth are of primitive character, of different forms in the same jaw, each with many cusps. The fins are without spines, the pectoral fin having the three basal cartilages (mesopterygium with propterygium and metapterygium) as usual among sharks.
Fig. 312.—Griset or Cow-shark, Hexanchus griseus (Gmelin) . Currituck Inlet, N. C.
The few living forms are of high interest. ”

“ Shark's-teeth, bits of ivory, or stone, for teeth, are set into the wood and retained in position by being strung on a thread which is secured at each end by a peg driven into the hole where the thread makes its exit from the base. Iron or copper tacks are driven into the ridge to serve for masticating purposes, the unequal wear of the wood and metal keeping up the desired roughness. Their full sets answer admirably for the mastication of food, but, as they do not improve the looks, they are worn but little for ornament. ”

“ Meanwhile the rod becomes divided into rings, and from each ring an arch of31 gristle growing upwards surrounds the nerve cord so as to protect it from injury, and the whole skeleton becomes firm and strong. But though the shark is one of the strongest of sea-animals he never loses this gristly state of his backbone or his skeleton; however much he may strengthen it by hard matter it never becomes true bone, but remains quite distinct from the skeleton of the bony or osseous fish. ”

“ If he could speak, he would probably tell us that, besides being troubled with his teeth, which he could not help keeping in use, he had been gifted with enormous abdominal viscera, and that, more particularly, a third of his body is occupied by spleen and liver. The bile and other digestive juices which are secreted from such an immense apparatus, and poured continually into the stomach, tend to stimulate appetite prodigiously—and what hungry animal with good teeth was ever tender-hearted? In truth, a shark's appetite can never be appeased ”

“ The enamel is derived from the outer layer of the embryonic dog-fish, the epiblast, which also gives rise to the epidermis; while the dentine and bony base arise in the underlying mesoblast, the dermis. A mammalian tooth has essentially the same structure: an outer coat of enamel, derived from epiblast, overlies a mass of dentine, resting on bone, but the dentine is excavated internally, to form a pulpcavity containing blood-vessels and nerves. Most land animals, however, have teeth only in their mouths, and have lost altogether the external teeth which constitute the armour of the dog-fish. ”

“ The shark, as you see, has pointed teeth so arranged in rows that one row closes down between two other rows in the opposite jaw, and by a muscular arrangement the shark can work one jaw to right and left with lightning-like rapidity, making the saw-like row of teeth cut through almost anything after the manner of a reaping machine. ”

“ It is difficult to handle one freely without cutting one's fingers; and when we consider the tremendous leverage of a shark's jaws employed against each other like scissors, armed with rows of lancets, it is evident that nothing in the shape of flesh, gristle, or bone, could withstand them. Their capacity, too, is equal to their powers, for a pair of jaws taken from a shark of not more than nine feet long has been known to be passed down over the shoulders and body of a man six feet high without inconvenience. ”

“ It has been suggested that these were carved from the ribs of the manitus; the bones of which animal, p282 we are informed by Bartram, were much used by the Southern Indians for articles of use and ornament.
Fig. 197.—Half size.
Several of the fossil teeth of the shark recovered from the mounds are represented in the cut, Fig. 197. It will be observed that they are of different species. They seem to have been used for various purposes. Some have holes drilled through them near the base; others are notched, as if designed to form spear or arrow-heads. ”

“ In the bulk of the Devonian sharks these developed into what are significantly called "pavement teeth." They were solid plates of enamel, an inch or an inch and a half in width, with which the monster ground its enormous meals of Molluscs, Crustacea, sea-weed, etc. A new and stimulating element had come into the life of the invertebrate world. Other sharks snapped larger victims, and developed the teeth on the edges of their jaws, to the sacrifice of the others, until we find these teeth in the course of time solid triangular masses of enamel, four or five inches long, with saw-like edges. ”

“ The shark, with a jaw larger and stronger than a crocodile's, with a mouth deeper and more capacious, strikes also with his tail, in tremendous force and rapidity, enabling him to repel any sudden attack by confusing or stunning his foe, till he can turn on his back, which he is obliged to do ere he can use his mouth. ”

“ The mode of fighting with shark's teeth is as follows : the teeth being fixed in three rows on the palm and fingers of a species of glove ittade of the plaited bark of the hedho, and both hands being armed in this manner, every man endeavours to come to a close scufile with his antagonist, and to tear open his bowels with these horrid weapons. ”

“ The teeth vary a good deal in form. In the larger number of existing placoids they are of a sharp cutting shape, often with saw-like edges. Among the sharks they run along the jaws in numerous rows, of which, however, only the outer one is used, those behind lying in reserve to fill up the successive gaps in the front rank. The teeth do not sink into the jaw, as in the ganoids, but are merely bound together by the tough integument which forms the lips. ”

“ In early winter the sharks are caught with hook and line through holes in the ice.
The Esquimaux assert that they are insensible to pain; and Petersen assures me he has plunged a long knife several times into the head of one whilst it continued to feed upon a white whale [49] entangled in his net!! It is not sufficient to drive them away with sundry thrusts of spears or knives, but they must be towed away to some distance from the nets, otherwise they will return to feed. It must be remembered that the brain of a shark is extremely small in proportion to the size of its huge head. ”