The great white shark is known as “the man-eater.” It occasionally injures or kills swimmers, and sometimes attacks boats. Its appetite is huger sea lions, seals, and other large creatures have been found in the stomach of the shark. However, the piranha of South America is a more dangerous fish than this one. – sometimes in a whole condition – in white sharks’ stomachs. This shark also eats garbage and offal, at least occasionally.
The white shark inhabits temperate and tropical oceans all over the world, coming near shore fairly frequently in some regions. One specimen was thirty-six and one-half feet long, but mature females are usually about fifteen feet long, and few individuals arc found larger than this. A twenty-one-foot specimen weighed seven thousand pounds. The females bear living young.
The Thresher Shark, Alopias vulpinis, has an enormously elongated upper lobe of its tail fin which is often longer than all the rest of its body. This fin is apparently used in capturing prey. Riding herd on a school of fish, the thresher swims ’round and ’round them, all the while splashing with its great tail. Gradually it forces them closer and closer together, and finally goes in for the kill. Sometimes two threshers will work together in this fashion. Occasionally, the tail is used to strike prey such as sea birds and fish. The old belief that the thresher shark teams up with the swordfish to attack whales is untrue.
This temperate and tropical species occurs in the Atlantic and eastern Pacific, but whether the form found in the western Pacific and Indian oceans is the same species or not is still undecided. Thresher sharks grow to a length of twenty feet or more, about half of which is composed of the tail. The females bear living young, two to four at a time, about three feet long.
Threshers are harmless to man, although they sometimes cause trouble by becoming entangled in fishing nets.