Though exclusively inhabitants of the salt sea, they sometimes chase their prey into a river, putting up with fresh water for the nonce.
Sharks are found nearly all over the world, but much more abundantly in hot climates. Their numbers gradually diminish, farther and farther from the equator. In tropical waters they are often present in overwhelming multitudes; and a man who should venture to bathe in such parts, would be as a scrap of bread flung to a horde of hungry little fishes. In less than a minute nothing of him would remain.
Off Kurrachee, where the catching of them is systematically carried on, about forty thousand are slain every year. This is for the sake of their fins, from which gelatine is obtained for the Chinese. That so many are killed, as a regular thing, says much with respect to the vast hordes which are not killed.
Of small shallow-water sharks, the most widely known are varieties of Dog-fishes. Though not large enough to be a terror to man, they are an endless trouble to fishermen, destroying great numbers of captured fish in the nets, and biting off the hooks from fishing-lines.
Among larger species, one kind found in the North Atlantic is the huge mild-mannered Basking Shark, which at times lies long and lazily close to the surface of the water, in company with a school of comrades. Its teeth are unimportant, and it feeds on smaller creatures, not attempting to include man among its eatables. But since it often has a length of thirty feet, and, like most sluggish natures, is capable of being roused, it becomes dangerous when excited. A blow of its tail may easily smash in the side of a whaling boat.
The largest of these creatures is the vast Whale-shark, belonging to the Indo-Pacific Seas, sometimes over fifty feet in length, and stated even to reach seventy feet.
However, if accounts be correct, this giant is much less of an enemy to the whale than the Greenland Shark. In the fashion of some savage nations, the latter feeds deliberately upon the live whale, biting raw steaks at pleasure from the worried leviathan—“scooping and gorging lump after lump,” so long as it feels “dispoged.”
The Greenland Shark is credited with feeling no pain, and it is extremely difficult to kill, as the unfortunate whale attacked by it finds to his cost.
Worse than all, so far as human beings are concerned, are the famous Man-eating Sharks of tropical waters, which occasionally, but not very often, find their way to colder latitudes.
Among them, the Great Blue Shark, from fifteen to twenty-five feet long, and the awful White Shark, known sometimes to reach a length of thirty-seven feet, have an undesirable pre-eminence.