Chondrichthyes: Life History and Ecology

Are all sharks man-eaters?

If asked about the ecology of cartilaginous fish, most people would probably identify them as rapacious carnivores. Many sharks are predators on fish, squid, and marine mammals -- although comparatively few are dangerous to humans. However, other cartilaginous fishes, such as skates, rays, and chimaeras, live on crustaceans and molluscs; they lack the daggerlike teeth of predatory sharks, and their teeth take the form of heavy crushing plates. (Incidentally, the sting in a stingray's tail is not used for attack or predation; it is purely for defense.) It may come as a surprise that several large sharks, like the basking shark featured at the top of this page, have small teeth and feed on plankton. As they swim in the open ocean, water is taken in through the mouth and strained through the gill slits. The largest shark of all, the whale shark, is such a plankton feeder.

The picture of the basking shark was posted to the newsgroup by an unknown person. Thanks.