Dolphin (delphinus, Cuv.), a carnivorous cetacean mammal, found in most of the seas of the world. The dolphins, as generally restricted, have a convex forehead, and a beak or snout armed with teeth, separated from the forehead by a well marked furrow; they do not acquire the dimensions of the whales, being rarely more than 9 ft. long. The body is fusiform in shape, without evident neck, and terminated by the horizontal tail common to all cetaceans; the head is not disproportionately large, and both jaws are toothed; there are two pectoral fins, and toward the middle of the back is a fold of the skin which may be called a dorsal fin; the eyes are small, with bare lids; the external opening of the ear is small; the tongue is thick, soft, and but slightly movable; the skin is naked and soft, covered only by a thick mucosity. The teeth are simple, conical, and numerous, varying in number even in individuals of the same species. The cranium is very small compared with the face, concave, and much elevated in front and arched behind; the snout is narrow and elongated from the prolongation of the maxillaries and intermaxillaries, which are not curved forward above; the upper jaw is a little shorter than the lower; the maxillaries extensively overlap the frontals; the tubercles which represent the nasal bones are above the intermaxillaries, resting on the frontals; the parietals are below the maxillaries, and quite on the side; the symphysis of the lower jaw is extensive, and the bone is light and hollow.
The cervical vertebra), seven in number, are very thin, and united; the dorsals are 13, with as many pairs of ribs, their articular processes becoming effaced by age, commencing posteriorly, and the transverse being about as long as the spinous processes; the lumbar vertebrae are 18, with very-long transverse and spinous processes; a sacral vertebra can hardly be said to exist, as the pelvis consists of a rudimentary bone on each side suspended in the muscles; the caudal vertebrae are about 28, gradually decreasing in size, the • transverse processes disappearing about the 16th, and the spinous about the 20th; exclusive of the cervicals, there are about 60 vertebras in all; the V-shaped bones on the under surface of the bodies begin about the sixth caudal. The breast bone is composed of three bones, the first very wide, grooved in front, and usually pierced with a hole; the shoulder blade is fan-shaped, slightly concave; the clavicle is absent; the pectoral fin is composed of a very short humerus, with a large upper tuberosity, its lower extremity compressed antero-posteriorly, and uniting by a cartilaginous articulation on an irregular line with the bones of the forearm; the latter are almost rectangular, short and flat, the radius in front and the widest; the bones of the wrist, six or seven in number in two rows, form a flat pavement-like surface united by cartilage to the radius and ulna; there is a mere vestige of thumb, according to Cuvier, the index finger being the longest and having nine articulations with its metacarpal bone and phalanges, the third with seven, the fourth with four, and the fifth a mere tubercle.
This anatomical description will answer generally for dolphins and porpoises, and the allied genera. Dolphins are among the swiftest of cetaceans, and their speed is owing to the strokes of the powerful tail; the pectoral fins serve merely to balance and guide the body, and to carry the young. The eye and ear are of the mammalian type; the nasal passages seem destined only for the expulsion of water from the mouth and for the introduction of air into the lungs, and are generally considered as not endowed with an average sense of smell; the taste must be very imperfect, and the sensibility of the naked skin low. The teeth are formed only for seizing and retaining prey, which is swallowed whole. Authors differ as to the stomach, some making it single, but most dividing it into three, four, or five compartments more or less complicated; the intestine is simple, 10 or 11 times as long as the body, and gradually diminishing from the stomach to the anus. The dolphin is not a fish, but an air-breathing mammal, warm-blooded, viviparous, and suckling its young.
Though shaped like fishes, inhabiting the water exclusively, and moving in the same manner with them, it must come to the surface by means of its horizontal tail, and take in air through the single spiracle on the top of the head, which it can do when the mouth is full of water by means of the upward prolongation of the larynx into the nasal passages, and the shutting off of its cavity by muscular action from the mouth and oesophagus; the external opening of the spiracle is guarded by a valve, which prevents the entrance of water when the animal plunges beneath the surface. The water taken into the mouth with the food can be made to pass out in a jet from the spiracle, by the closing of the pharynx, and the forcing of the liquid into the nose through the passage in which the larynx is elevated during respiration. Under the skin, in front of the nostrils, are two large cavities covered with muscles; into these the water is sent, and remains until the animal chooses to eject it; then closing a valve at their entrance, the water is sent forth by the contraction of the muscles. The dolphin family make a feeble moaning or plaintive noise, which has often been noticed when they have been stranded alive.
The circulation is carried on as in other mammals; only, in order to enable them better to remain under water, there is a plexiform arrangement of the arteries within the chest and near the spine, which serve as reservoirs of pure blood during immersion; these do not communicate directly with veins, and their contents can be taken into the circulation as circumstances require. The reproductive organs are the same as in other mammals, and their functions are similarly performed; the testes are within the abdomen; the prostate gland is large, but the seminal vesicles are absent; the mammae are two, with the nipples concealed in a fold of skin, except during lactation, when they protrude on each side of the genital opening. The kidneys are made up of many small glands united. The brain is very wide, the hemispheres however covering only a portion of the cerebellum; the convolutions are numerous and complicated, but narrow; the olfactory lobes seem to be wanting; the cerebellum is well developed, with distinct median and lateral lobes. This great cerebral development affords some ground for the ancient belief in the superior intelligence of the dolphin.
The history of this animal, sacred to Apollo, though encumbered with fabulous and superstitious accounts, doubtless contains much truth which whale-hunting moderns have not cared to examine. - As the dolphin family till recently included all ordinary cetaceans with small heads, the divisions which have since been made are very numerous, and no system of classification as yet offered can be called natural. Such only, therefore, as would not come more properly under other popular titles will be briefly alluded to. At the head of the list is the common dolphin (D. delphis, Linn.); this, from the shape of the beak, is vulgarly called the "goose of the sea;" it was the hieros ichthya (sacred fish) of the ancients, the favorite of Apollo (whose most famous oracle bore its name), and the supposed benefactor of man; it is seen on very ancient coins and medals, and formed a conspicuous object on the coat of arms of the princes of France; from it was named the province of Dauphiny, which gave the title to the heir apparent to the French throne. It attains a length of from 6 to 10 ft., and its proportions are admirably adapted for the speed which is its characteristic. It is dark on the back, grayish on the sides, and satiny white underneath.
The geographical range of this species embraces the seas of Europe, the Mediterranean, and the northern and temperate Atlantic; other species are found in the seas of America, Asia, and Africa. Vessels frequently meet them in large numbers, shooting under the bows, springing out of the water, and racing with their fellows; their speed is such that they easily outstrip the swiftest steamer. The dorsal fin is about 9 in. high, a little behind the middle of the back; the pectorals, about 2 ft. from the snout, are somewhat longer than the dorsal, narrow and rounded; the tail is crescent-shaped, with a notch in the middle, and about a foot wide; the jaws have from 32 to 47 teeth on each side, according to age, simple, conical, largest in the middle of the series. During rapid motion the tail is bent under the body, and then suddenly brought into a straight line. The dolphin lives principally upon fish, which it pursues even into the midst of the fishermen's nets. F. Cuvier thinks an examination of the habits of the dolphin will disclose a foundation in fact for the supposed intelligence of this species.
In former times the flesh of the dolphin was as much esteemed for food as it is now neglected; in the 16th century its price was so high that it was only seen on the tables of the rich; in the time of Dr. Caius, founder of the college of that name at Cambridge, a dolphin was thought a worthy present for the duke of Norfolk, who in turn distributed it to his friends. In France the dolphin could be eaten during Lent without sin, all cetaceans being then considered fish. The meat is dark-colored, palatable and nutritious, and is now often eaten by seafaring men on long voyages. The D. tursio (Fabr.), the nesarnak of the Greenlanders, has a thick body, a flattened, short beak, obtuse teeth, a dorsal fin, and a blackish color, except a small part of the abdomen, which is whitish; it attains a size of 9 to 15 ft., has from 88 to 100 teeth, and inhabits the Atlantic from the shores of Europe to those of Greenland; it is less active than the common dolphin. Another name for it is the bottle-nosed dolphin or whale.
Other dolphins are the lead-colored (D. plumbeus, Dussumier), about 8 ft. long, of a leaden-gray color, rather sluggish in its movements, with about 136 teeth, found on the coast of Malabar, near the shore, where it pursues the pilchards; the bridled (D. frenatus, Duss.), less than 6 ft. long, having on the ash color of the cheeks a black band extending from the angle of the mouth below the eye, found in the neighborhood of Cape Verd; the eye-browed (D. super-ciliosus, Lesson), about 4 ft. long, brilliant blackish blue above, silvery below, with a white streak over the eye, found in the neighborhood of Cape Horn; the funenas of the Chilians (D. lunatus, Less.), about 3 ft. long, with a slender beak, fawn-colored above, white below, with a dark brown cross on the back, in front of the dorsal fin, numerous in Conception bay. - Among the delphinidoe which would not be better described elsewhere is the genus dclphinapterus of Lacepede, having no dorsal fin, and a slender transversely flattened beak, separated from the cranium by a deep furrow.
Peron's dolphin (D. Peronii, Cuv.) is about 6 ft. long, elegant in form and proportions, of a deep bluish black above, with the snout, sides, pectorals, abdomen, and part of the tail silvery white; the teeth are about 39 on each side of each jaw; like the rest of the genus, it is found in high southern latitudes. The allied genus beluga (Bon.) has an obtuse, conical, and rounded head, without prominent beak, and without dorsal fin. The whitefish, or white whale (B. borea-lis, Less.), is a beautiful cream-white dolphin, symmetrical, and very swift; the length varies from 12 to 20 ft.; the teeth, according to Cu-vier, are 9/9-9/9; being well covered with fat, it is sometimes chased by coast whalers, especially about the mouths of rivers, where it feeds upon the cod, haddock, flounder, and other fish; it is • essentially arctic, though it descends to the temperate regions of both hemispheres; it has been seen in the river St. Lawrence as high up as Quebec. The genus globicephalus (Less.) includes the D. globiceps (Cuv.), commonly called the de-ductor, social, bottle-head, blackfish, or howling whale; it resembles the beluga in the shape of the head, but differs from it in having a dorsal fin; the length is from 16 to 24 ft., and the general color a shining jet-black; the teeth are from 20 to 28 in each jaw; its favorite resort is the northern temperate ocean in both hemispheres; it is included by De Kay in the fauna of New York; it herds in great numbers, apparently following a leader, and is easily driven upon beaches; the proper name is globicephalus melas (Less.). Some species of the genus have been found in the Mediterranean. The long-beaked dolphins (delphinorhynchus, La-cep.) have a prolonged snout, thin and narrow, not separated from the cranium by a furrow; the straight jaws are furnished with numerous sharp teeth, and the dorsal fin is single; some of the species attain the length of 36 ft.
The best known, D. micropterus, Cuv., or D. Sow-erbyi, Desm., is remarkable for the snout being four times the length of the cranium, and for the curvature upward and forward of the posterior part of the intermaxillaries, carrying with them the maxillaries, frontals, and occipital; it is a northern species, and has been found stranded on the French and English coasts. There are two remarkable genera of fresh-water dolphins, one of which, the dolphin of the Ganges (platanista Gangetica, Gray.), will be described under Soosoo, the Bengalee name. The other is the Bolivian dolphin (inia Boliviensis, D'Orb.), found in the tributaries of the Amazon and the neighboring streams and lakes, even to the foot of the Andes; the beak is long, but cylindrical, bristled round with strong hairs, and obtuse at the end; the teeth are about 134, resembling incisors in front and molars behind ; the body is short and slender, the pectorals large, the dorsal small and behind the middle of the back ; the skin is fine and smooth ; the average length of the adult is about 7 ft.; the color varies from pale blue to blackish above, and is rosy beneath.
It comes frequently to the surface, and is comparatively slow in its movements; its food consists almost entirely of fish, which are devoured with the snout above water; it is killed by the natives for its oil. This curious animal seems to form an intermediate type between the carnivorous and the herbivorous or sirenoid cetaceans. - The delphinidoe are of little value to the whaler, as they are difficult to catch, and their covering of fat is much less than in the whales. Near the mouths of rivers and on the coasts herds of them are occasionally hunted with profit for their oil and their skins, and in high northern regions even for food. Many genera of delphinidoe inhabited the seas during the tertiary epoch, some very like the present dolphins, others very different from them. Their fossil remains are found abundantly in the miocene, pliocene, and diluvial strata of America and Europe. - The name of dolphin was long ago given by Dutch navigators to a scomberoid fish of the genus coryphoea (Linn.), inhabiting the Mediterranean and the seas of warm and temperate regions.
The genus has no detached finlets, no isolated dorsal spines, and no armature on the tail; the body is moderately long, more or less compressed, and covered with small scales; there is a single dorsal fin, with flexible rays, extending from the head to near the caudal; the ventrals are thoracic. The generic name is derived fromsummit, in reference to the elevated shape given to the forehead by a bony crest of the interparietal and frontal which rises between the intermaxillaries and extends to the occiput; this gives a trenchant aspect to the head, with a very convex facial profile; the eyes conse-quently seem low. The mouth is large having card-like teeth on the jaws and palatal bones. The dolphin of the Mediterranean, so famous for the beauty of its colors when dying, is the C. hippurus (Linn.). Many writers have followed the Dutch error as to the name of this fish, and that of dolphin is taken away by sailors from the cetacean and given to the scom-beroid. This species grows to the length of about 5 ft.; the colors are bluish green above, with azure and golden reflections, and citron yellow below, with pale blue tints; the pectorals are partly leaden and partly yellow, the ventrals yellow below and black above, the anal yellow, and the iris golden. In the Atlantic is the C. equisetis (Linn.), with a shorter body and more elevated head. On the coast of South America is the G. dorade (Val.), from the name given to the genus by the Portuguese. About a dozen other species are described in different parts of the globe.
They are exceedingly active, strong, and voracious, pursuing the flying fish, forcing them to leave the water, and seizing them as they descend into it again. Nothing can be more beautiful in a calm sunny day, in the clear water of mid-ocean, than to see these brilliant creatures darting around the vessel, displaying their ever-varying tints of golden, blue, and green, with every movement. They gather around any floating object, and are readily caught by a hook or harpoon; when brought upon deck the beautiful play of rapidly changing colors commences, produced, as in the chameleon and the cuttle fish, by changes in the surface by muscular action, as may be seen by the constant undulation of the long dorsal fin. The flesh is considered good food; it is white, and rather dry. Sailors have an idea, which is probably true, that it is sometimes unwholesome and even poisonous, and they are in the habit of boiling a piece of silver money with the fish to detect the fact; if the piece be tarnished by the boiling, the fish is rejected; if it remain bright, it is fit for the table.
Common Dolphin (Delpbinus delphis).
Bottle-nosed Dolphin (Delphinus tursio).
White Dolphin (Beluga borealis).
Deductor (Globicephalus melas).
Bolivian Dolphin (Inia Boliviensis).