between the ends of the baleen-plates. The surface water of the ocean swarms with animal 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 mandibular 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 vertebræ 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 vertebræ are remarkably large, numerous, 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 nonconductor of heat and serves to maintain the temperature of the body, thus replacing the external coat of hair present in other mammals but wanting in all cetaceans. The salivary glands of a whale are rudimentary or wanting, the stomach is many-chambered and quite peculiar, the intestinal caecum is wanting or very small, the gall-bladder is wanting, the larynx has a peculiar shape, the blood system is remarkable for its plexuses, both arterial and venous, the brain is large and round, with numerous and complex cerebral surface convolutions, 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, sometimes 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 carnivorous, 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 small 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 derived almost wholly from whale oil, but kerosene has now entirely supplanted the animal oil. Numerous 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. Ambergris (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 purification by refining it is a white crystalline substance 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 substitutes. Whalebone is exceptionally 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.
| STRUCTURE OF WHALEBONE. |
|
1. Diagram of the matrix of the baleen-plate, the dotted line, a, showing the outline of the pulp which forms b, the central fibrous part of the plate; c, external layers of firm substance formed by the elastic cementing material. 2. A vertical section of four baleen-plates in situ, the transverse bar at the top represents the vascular gum from which the pulps proceed that penetrate the base of the plates. Below this is shown the elastic substance cementing the plates together, beyond which the plates project free and terminate in a fringe of bristles. 3. Transverse section of a portion of a baleen-plate showing the area of the tubular cavities of the coarse central fibres, and the outer, denser substance. |
For obvious reasons, the study of the anatomy,
development, and natural history of whales is
attended with unusual difficulties, and the
accumulation of large series of specimens in
museums 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
geographical distribution is practically unknown.
Not more than 25 well-defined species of whale
can be 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 Mysticete being generally accepted, though
under varying names.
The Denticete (Odontoceti, Delphinoidea) include, besides the toothed whales, all those other cetaceans known as dolphins, narwhals, porpoises, killers, etc. The most important whale in this group is the sperm whale (Physeter macrocephalus), also called cachalot and spermaceti whale. It has a very wide geographical range,
