A carnivorous cetacean with large teeth, often found in British seas.
Having, then, shown that whales are mammals, we must now determine the chief features of the more typical members of the order. The extremities of whales are characteristic: a large head, occupying in some species as much as one-third of the total length; and the afore-mentioned forked, or lobed, tail set laterally. The flippers, which bear only a slight resemblance to the pectoral fins in fishes, are in reality hands encased in swimming-gloves. In some whales these hands are five-fingered, in others the fingers number only four, but many of the fingers contain more bones than the fingers of man. In some whales we find a dorsal fin, and this, as also the flippers, acts as a balancer. In no whale or porpoise is there any external trace of hind limbs, but the skeleton of some kinds shows in varying stages of degradation a rudimentary bone answering to this description. Perhaps however, the most distinctive feature of whales is the blow-hole, situated, like the nostrils of the hippopotamus, on the upper surface of the head, and similarly enabling the animal to breathe the air without exposing much of its head above the surface of the water. The blow-hole (or blow-holes, for whalebone-whales have two) may be said to take the place of nostrils as regards the breathing, though perhaps no sense of smell is included in its functions. In the Sperm-whale, or Cachalot, there is a single
-shaped blow-hole near the end of the snout. The well-known spouting of whales is merely the breathing out of warm vapour, which, on coming in contact with the colder air—and it should be remembered that most whaling is carried on in the neighbourhood of icebergs—condenses in a cloud above the animal's head. I have seen many a sperm-whale spout, and the cloud of spray, often mixed with a varying volume of water if the whale commences to blow before its blow-hole is clear of the surface, drifts forward over the forehead. This is due to the forward position of the blow-hole. I never to my knowledge saw a whalebone-whale spouting, but its double jet is said to ascend vertically over its back, and this would in like manner be accounted for by the more posterior position of the blow-holes. Having filled its lungs, which are long and of simple structure, with fresh air, in enormous draughts that fill the great cavities of its chest, the whale sinks to the depths. There, in ordinary circumstances, it will lie for a quarter of an hour or more, but the pain of the harpoon and the knowledge that there is danger at the surface may keep it below for as much as an hour. When it has to breathe again, a few powerful strokes from the laterally set tail suffice to bring it quickly to the surface. This is not the place for a detailed anatomy of the whale, but no one can fail to notice with admiration such parts of its equipment for the battle of life as the structure of its windpipe, which enables it to breathe with comfort with its mouth full of water, the complicated network of blood-vessels that ensures the slow and thorough utilising of all the oxygen in its lungs while it remains at the bottom, and the elastic cushion of blubber that makes this gigantic animal indifferent to extremes of pressure and temperature. Thanks mainly to its coat of blubber, the whale exists with equal comfort at the surface or hundreds of fathoms below it; in the arctic or in tropical seas.
Photo by A. S. Rudland & Sons.
SHORT-BEAKED RIVER-DOLPHIN.
In this type the head is produced into a beak, supported in the upper jaw by a mass of ivory-like bone.
It is not perhaps in keeping with the plan of this work that we should consider in detail the soft parts of the whale's inside. One or two parts of its feeding and digestive mechanism may, however, offer some points of passing interest. The complex stomach, which is divided into chambers, like that of the ruminants already described, has suggested that the latter function may in a modified process be performed by whales. It is, however, evident that the teeth of toothed whales are in no way adapted to the act of mastication, which is inseparable from any conception of ruminating, while the toothless whales have as complicated a stomach as the rest. Mr. Beddard, writing on the subject in his interesting "Book of Whales," takes the more reasonable view that the first chamber of the stomach of whales should be regarded rather as a storehouse in which the food is crushed and softened. The teeth of whales, the survival of which in the adult animal offers the simplest basis of its classification under one or other of the two existing groups, or sub-orders, are essentially different from the teeth of many other kinds of mammals. It cannot, perhaps, be insisted that the distinctive terms employed for these two categories of whales are wholly satisfactory. For instance, the so-called "toothless" whales have distinct teeth before birth, thus claiming descent from toothed kinds. On the other hand, the so-called "toothed" whales are by no means uniformly equipped in this respect, some of the porpoises having as many as twenty-six teeth, distributed over both jaws, while the bottlenoses have no more than two, or at most four, and these in the lower jaw only. Only the lower jaw, in fact, of the great sperm-whale bears teeth that are of any use, though there are smaller and functionless teeth in the gums of the upper. The teeth of whales, by the way, are not differentiated like our canines and molars, but are all of one character. Although, in "toothless" whales, the foetal teeth disappear with the coming of the baleen, or whalebone, the latter must not, in either structure or uses, be thought to take their place. The plates of whalebone act rather as a hairy strainer. Unless we seek a possible analogy at the other end of the mammalian scale, in the Australian duckbill, the feeding of the whalebone-whales is unique. They gulp in the water, full of plankton, swimming open-mouthed through the streaks of that substance. Then the huge jaws are closed, and the massive tongue is moved slowly, so as to drive the water from the angles of the mouth through the straining-plates of baleen, the food remaining stranded on these and on the tongue. The size and number of the baleen-plates appear to vary in a degree not yet definitely established; but there may, in a large whale, be as many as between 300 and 400 on either side of the cavernous mouth, and they may measure as much as 10 or 12 feet in length and 7 or 8 feet in width.
