Are sharks fish

Also, unusually for fish that spawn eggs, around 60% of species of sharks give birth to live young, called pups.

Q. Are all sharks carnivores

A. No, although most sharks are meat eaters, some, notably the whale shark, eat plankton.

Q. Are all sharks man hunters

A. No, of the 360 different kinds of sharks, only four are truly harmful to humans. Humans are much more of a danger to sharks.

One of the biggest threats to sharks is the demand for shark fins for delicacies, medicines and aphrodisiacs. Conservationists estimate that about 100 million sharks are killed every year in this trade.

Q. How many sets of teeth do sharks go through in a lifetime

A. All sharks differ, but on the whole, sharks have hundreds of teeth throughout their life. Shark teeth grow in parallel rows, some teeth fall out every time they eat, rows of replacement teeth develop continuously throughout their life behind the outer row of functional teeth.

The shape of a sharks teeth and jaws give away what kind of feeders they are. A mako's teeth are thin and pointed. ideal for grabbing and holding prey; the great white's are serrated and, wedge-shaped for slashing its prey; and the nurse shark, which feeds at the bottom of the sea, has small conical teeth, perfect for crushing the shells of crabs and molluscs.

Q. How long do sharks live for

A. The average life span of a shark is 25 years, but some can live to be 100.

Q. How long have sharks been around for

A. Sharks and their relatives, the skates and rays, have enjoyed considerable success during their nearly 400 million years of existence on earth. One reason for this certainly is their little understood ability to resist disease. Sharks aren't immune to illness, but their incidence of disease is much lower than among the other fishes.

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by Lisa Cardy