The Sperm-Whale, or Cachalot (Physeter macrocephalus), rivals the great smooth-backed whales both in its various utility to man and the colossal dimensions of its unwieldy body. The largest authentically recorded size of the uncouth animal is seventy-six feet by thirty-eight in girth; but whalers are well contented to consider fifty-five or sixty feet the average length of the largest examples they commonly obtain. The male, however, alone attains these ample proportions; the adult female does not exceed thirty or at most thirty-five feet, so that there is a greater disproportion of size between sexes than in any other known species of cetaceans.
The form of the beast is without symmetry, and from the general absence of other prominent organs than the tail or pectoral fins, can be compared to little else than a dark rock or the bole of some giant tree. The prevailing colour is a dull black, occasionally marked with white, especially on the abdomen and tail. The summit of the head and trunk presents a plane surface, until about the posterior third of the back, whence arises a hump or spurious fin of pyramidal form, and entirely composed of fat. From this embossed appendage an undulating series of six or eight similar, but smaller elevations, occupies the upper margin or ridge of the tail to the commencement of the caudal fin. The pectoral fins or paddles are placed a short distance behind the head; they are triangular in shape, diminutive as compared with the size of the whale, and being connected to the trunk by a ball and socket joint, possess free movement, either vertical or horizontal.
Cuttle-fish (Sepia).
Owing to the flexibility of the tail, the movements of the tail-fin, or "flukes," which sometimes measures eighteen feet across, are exceedingly extensive, whilst its power may be estimated by the gigantic bundles of round tendons, which pass on either side the loins, to be inserted into its base. Whether wielded in sportive mood or in anger, its action is marked by rapidity and ease, and when struck forcibly on the surface of the ocean, produces a report which may be heard at a considerable distance. In progression, the action of this organ is precisely the reverse of that of the tail of the lobster, for whilst the latter animal swims backward by striking the water with its tail from behind forwards, the cachalot and other cetaceans swim forward by striking with their flukes in the contrary direction, the fin being brought beneath the body by an oblique and unresisting movement; while the act of springing it back and straightening the tail propels the animal ahead with an undulating or leaping gait. When employed offensively the tail is curved in a direction contrary to that of the object aimed at, and the blow is inflicted by the force of the recoil. The lower jaw appears diminutive, slender, and not unlike the lower mandible of a bird. When the mouth is closed it is received within the soft parts pendent from the border of the upper jaw, and is nearly concealed by them. True and serviceable teeth are situated only in the lower jaw, and are received into corresponding sockets in the upper jaw. In aged males they are of great solidity and size, attaining a weight of from two to four pounds each; their entire structure is ivory. This powerful armament shows us at once that the food of the cachalot must be very different from that of the whalebone cetaceans; it generally consists of cuttle-fish, many kinds of which are ejected from its stomach when it is attacked by the boats, as well as after death. Owing to the great projection of the snout beyond the lower jaw, it may be requisite for this whale to turn on its side or back to seize its more bulky prey; a supposition strengthened by the fact that, when the animal attacks a boat with its mouth, it invariably assumes a reversed posture, carrying the lower jaw above the object it is attempting to bite. As long as it continues on the surface of the sea, the cachalot casts from its nostril a constant succession of spouts, at intervals of ten or fifteen seconds. As in all whales, the jets are not, as frequently imagined, water-columns, but a thick white mist ejected by one continual effort to the height of six or eight feet, and rushing forth with a sound resembling a moderate surf upon a smooth beach. The peculiar fat or sperm which renders the cachalot so valuable, is chiefly situated in the head. Junk is the name given by the fishermen to a solid mass of soft, yellow, and oily fat, weighing between two and three tons, based on the upper jaw, and forming the front and lower part of the snout; while the cavity called case is situated beneath and to the right of the spouting canal, and corresponds to nearly the entire length of that tube. It is filled with a very delicate web of cellular tissue, containing in large cells a limpid and oily fluid, which is liberated by the slightest force. The quantity, chiefly spermaceti, contained in this singular receptacle, is often very considerable, nearly 500 gallons having been obtained from the case of one whale. So vast an accumulation of fat has obviously been intended to insure a correct position in swimming, to facilitate the elevation of the spiracle above the surface of the sea, and to counteract the weight of the bony and other ponderous textures of the head; objects which in the Greenland whale are sufficiently attained by a similar accumulation of fat in the lips and tongue, and by the more elevated situation of the spout-hole.
While the large whalebone whales generally roam about in solitary couples, the cachalot forms large societies. Schools, consisting of from twenty to fifty individuals, are composed of females attended by their young, and associated with at least one adult male of the largest size, who generally takes a defensive position in the rear when the school is flying from danger.
Pods are smaller congregations of young or half-grown males, which have been driven from the maternal schools. Two or more schools occasionally coalesce to a "body of whales," so that Bennett[L] sometimes saw the ocean for several miles around the ship swarming with sperm leviathans, and strewn with a constant succession of spouts. These large assemblies sometimes proceed at a rapid pace in one determinate direction, and are then soon lost sight of; at other times they bask and sleep upon the surface, spouting leisurely, and exhibiting every indication of being at home, or on their feeding ground. Like most gregarious animals, the cachalots are naturally timid. A shoal of dolphins leaping in their vicinity is sufficient to put a whole school to flight: yet occasionally fighting individuals are met with; particularly among those morose solitary animals that most likely from their intolerable character have been turned out of the society of their kind. The central deserts of ocean, or the neighbourhood of the steepest coasts, are the chief resort of the cachalot; and so great is the difference of his habitat from that of the smooth-backed whales, that during the whole time Bennett was cruising in quest of cachalots, he in no single instance saw an example of the true whale. The cachalot is more especially found on the line-currents, which extend from the equator to about the seventh degree of north and south latitudes, yet it has been noticed in the Mediterranean, and one individual, a stray sheep indeed, has even been captured in the Thames.
[L] Narrative of a Whaling Voyage round the Globe.
The Narwal, or Unicorn-fish, attains a length of from twenty to twenty-five feet. He is of a grey-white colour, punctured with many white spots, and as his head is not disproportionate to the length of his body, may rank among the handsomest cetaceans. He distinguishes himself, as is well known, from all other members of the family by the long twisted tooth or horn projecting horizontally from the upper jaw. This mighty weapon, the true use of which has not yet been fully ascertained, was formerly sold at a very high price, as proceeding from the fabulous unicorn; at present, it is only paid according to the worth of its excellent ivory, which is harder, heavier, and less liable to turn yellow than that of the elephant. The whalers are therefore highly delighted when they can pick up a chance narwal, but this only succeeds in narrow bays; for the unicorn-fish is an excellent swimmer, and extremely watchful. In spite of his menacing appearance, he is a harmless sociable creature, fond of gambolling and crossing swords playfully with his compeers. It is remarkable that the opening of the mouth of so huge an animal is scarcely large enough to admit the hand of a man. Scoresby found in the stomach of a narwal remains of cuttle fishes, which seem to form his chief aliment, besides pieces of skates and plaice. The narwal is frequent about Davis' Straits and Disco Bay, but is nowhere found in the Pacific, having most likely not yet discovered the north-western passage. He rarely wanders into the temperate seas, yet one was caught, in 1800, near Boston in Lincolnshire, and two others, in 1736, on the German coast of the North Sea.
The Dolphin tribe is distinguished from the cachalot by a more proportionate head; from the narwal by the absence of the long horn; and generally possesses sharp teeth in both jaws, all of one form. The number of species is very great; Linnæus distinguished four sperm-whales and three dolphins; now many naturalists acknowledge but one species of the former, while the dolphins have increased to more than thirty, and many are as yet unknown.