In the toothless whales the roof of the mouth is provided with a large number of verti cal horny plates, quite close together, placed transversely on each side, so that there is a hare space in the median line. The outer end of each plate is smooth and hard. hut the inner end is frayed out into long bristly Mires. so the roof of the mouth looks as though covered with hair. ( See WHALEBONE. ) This whole ap paratus serves as a sieve for straining out the minute animals on which these whales feed, the water being taken into the mouth anteriorly and then let run out at the sides of the mouth, between the ends of the baleen-plates. The sur face water of the ocean swarms with iinimal life; on the feeding grounds of the whale this consists largely of mollusks of various kinds, together with more or less crustacean material. All this animal life is collectively known by whale-fishermen as 'brit' and is the only food supply of the toothless whales. Owing to the large size of the mouth, the maxillary and man dibular bones of the skull are greatly elongated, giving the cranium proper a disproportionately small appearance, although it is in reality of relatively good size. There are always seven vertebne in the neck, but they are crowded close together, are practically immobile, and are more or less fused together into a single piece. The remaining vertebne are remarkably large, nu merous, and very freely movable upon each other. There is no union of any of them in the sacral region. All the bones of a whale are spongy, the cavities being filled with oil.
There are many peculiarities in the soft parts of the whales, notably the development of `blubber,' a layer of fat, consisting of a dense mesh of areolar tissue, the interstices of which are filled with oil. This is an extraordinary non conductor of heat and serves to maintain the temperature of the body, thus replacing the ex ternal coat of hair present in other mammals hut wanting in all cetaceans. The salivary glands of a whale are rudimentary or want ing, the stomach is many-chambered and quite peculiar, the intestinal ea-cum is wanting or very small, the gall-bladder is wanting, the larynx has a peculiar shape, the blood system is re markable for itAi plexuses, both arterial and venous, the brain is large and round, with numerous and complex cerebral surface convolu tions, and the mammary glands are situated far back, one on each side of the female reproductive opening. There is a special arrangement of dilated ducts and compressor muscles, so that the milk can be forced into the mouth of the young one in considerable quantities at a time, by the action of the mother, so that 'sucking' under water is made feasible.
Whales are very widely distributed in all parts of the ocean and are frequently gregarious, some times occurring in thousands. Some species,
however, are generally seen singly or in pairs. A few species appear to be regularly migratory, while others wander almost at will, restricted by no natural barriers. All whales are car nivorous, but only the killers (q.v.) eat other warm-blooded vertebrates. Fishes and squids are the chief articles of diet of the toothed whales, while smell mollusks and other invertebrates maintain the whalebone whales. Whales are generally timid, inoffensive animals, active and graceful in their movements and very affectionate toward one another. The parents and offspring are especially attached to each other.
Commercially whales are of great importance, although they were much more so in the past. Ambergris. spermaceti, whale oil. whalebone, and ivory are the principal substances supplied by these animals, although leather is made from the skins of some of the smaller species. Before the discovery of petroleum. illuminating oil was de rived alinost wholly from whale oil, but kerosene has now entirely supplanted the animal oil. Nu merous substances have also been discovered or invented for replacing whalebone, which has been steadily increasing in price, and has thus become too expensive for many purposes. Am bergris (q.v.) is only incidentally a product of the whale fishery, but spermaceti is one of the principal productions of the sperm whale. It is a peculiar oily substance, which at the body temperature of the whale is a whitish fluid, but on cooling becomes solidified. After purifica tion by refining it is a white crystalline sub stance used largely in pharmacy and in making candles. It is nearly odorless and tasteless. Whale oil and whalebone are still widely used, although so generally replaced by cheaper sub stitutes. Whalebone is exeeptionally tough and elastic, and no perfect substitute has yet been found. Whale ivory is derived from the teeth of the sperm whale, which are five or six inches long. very solid, and composed of a superior grade of ivory.
For obvious reasons, the study of the anatomy, development, and natural history of whales is attended with unusual difficulties, and the ac cumulation of large series of specimens in mu seums is out of the question. It is therefore a matter of considerable question whether a given species of whale wanders into all parts of the ocean, and the number of species and their geo graphical distribution is practically unknown. Not more than 25 well-defined species of whale can he recognized, though nearly three times that many have been named. The classification is based primarily on the presence or absence of teeth after birth, the two suborders Denticete and l\lysticete being generally accepted. though under varying names.