The object of the whole series of baleen-plates with which the palate is furnished, is as follows : The Whale is a strictly carnivorous or zoophagous animal, but owing to the absence of teeth and the comparatively small calibre of the oesophagus, it lives upon very diminutive animals. The Whale, in fact, lives mostly upon the shoals of small Pteropodous Molluscs, Crustacea, Ctenophora and Medusae, which swarm in the arctic seas. To obtain these, the whale swims with the mouth opened, and thus fills the mouth with an enormous mass of water. The baleen - plates have the obvious function of a " screening apparatus." The water is strained through the numerous plates of baleen, and all the minute animals which it contains are arrested and collected together by the inner fibrous edges of the baleen-plates. When, by a repetition of this process, the Whale has accumulated a sufficient quantity of food within the central cavity of the mouth, it is enabled to swallow it, without taking the water at the same time.
We have now to speak of a phenomenon which has given rise to a considerable amount of controversy - namely, what is known as the "blowing" or "spouting" of the whale. In all the Cetaceans the nose opens by a single or double aperture (the latter in the Balaenidae) upon the top of the head, and these external apertures or nostrils are known as the "blow-holes" or "spiracles." The act known to the whalers as "blowing," consists in the expulsion from the blow-holes of a jet of what is apparently water, or at any rate looks like it. This act is performed by the whale upon rising to the surface, and it is usually by this that the whereabouts of the animal is discovered. The old view as to what takes place in the act of blowing is, that the whale is really occupied in getting rid of the surplus water which it has taken in at the mouth and strained through the baleen-plates. The modern and undoubtedly correct view, however, is, that the water which has been strained through the baleen really makes its escape at the sides of the mouth, and does not enter the pharynx to be expelled through the nose. Upon this view the apparent column of water emitted from the blow-holes in the act of blowing consists really of the expired air from the lungs, the contained watery vapour of which is suddenly condensed on its entrance into the cold atmosphere. With the expired air there may be such water as may have gained access to the nose through the blow-hole, for the expulsion of which proper provision exists in the form of muscular diverticula of the nasal cavity. It is also possible that the column of air in being forcibly expelled from the blow-hole may take up with it some of the superincumbent water.
Fig. 383. - Diagram of the baleen-plates of a Whale. a a Section of the palatal surface of the upper jaw, showing the strong median ridge or keel; b b Baleen-plates sunk at their bases in the palate; f f Fibrous margin of baleen-plates.
The skin in the Right Whale is perfectly smooth and naked, but it is underlaid by a thick layer of subcutaneous fat, which varies from eight to fifteen inches in thickness, and is known as the "blubber." The blubber serves partly to give buoyancy to the body, but more especially to protect the animal against the extreme cold of the medium in which it lives. It is the blubber which is chiefly the object of the whale-fishery, as it yields the whale-oil of commerce.
The whale which is captured in the South Atlantic is not the same species as the Greenland Whale, and is termed the Balaena australis. It is much about the size of the Right Whale, averaging about fifty feet, but the head is proportionately smaller. Another Atlantic species is the B. Biscayensis. In the South Pacific occurs Balaena antipodarum, and in the North Pacific we meet with the B. faponica along with the B. mysticetus or Right Whale of the North Atlantic (Van Beneden).
The only remaining members of the Balaenidae which require notice are the Rorquals and Hump-backed Whales, constituting the group of the ' Furrowed" Whales. These are collectively distinguished by having the skin furrowed or plaited to a greater or less extent, whilst the baleen-plates are short, and there is a dorsal fin. The specific determination of these animals is a matter of great difficulty, but there would appear to be probably three well-marked genera : 1. The genus Megaptera, including the so-called Hump-backed Whales, in which the flippers are of great length, from one-third to one-fifth of the entire length of the body. 2. The genus Balaenoptera, comprising the so-called Rorquals or Piked Whales, in which the flippers are of moderate size. 3. The Finner Whales proper (Physalus).
In all these genera there is a dorsal adipose fin, so that they are all "Finner Whales." The Balaenopterae reach a gigantic size, being sometimes as much as eighty or one hundred feet in length. They are very active animals, however, and their whalebone is comparatively valueless, so that the whalers rarely meddle with them, though they are not uncommon, and are often driven ashore on our own coasts.
Fam. 2. Catodontidae. - The family of the Catodontidae or Physeteridae. comprises the Sperm Whales or Cachalots, with which we commence the series of the toothed Whales (Odon-toceti). They are characterised by the fact that the palate is destitute of baleen-plates, and the lower jaw possesses a series (about fifty-four) of pointed conical teeth, separated by intervals, and sunk in a common alveolar groove, which is only imperfectly divided by septa. The upper jaw is also in reality furnished with teeth, but these do not cut the gum.