Mammals only get two sets of teeth - milk (or baby) teeth and adult teeth. In all other toothed vertebrates, teeth keep coming in.

Sharks may grow 20,000 teeth in a lifetime. The teeth of the feared great white shark measure three inches long. The largest shark, 40-foot whale shark, has the smallest teeth of any shark - only 1/8th of an inch high.

A pair of tusks from an African elephant can weigh 465 pounds. Each of its molars can weigh 12 pounds. The tusks of the extinct straight-tusked elephant measured 16 1/2 feet long.

Walrus tusks can weigh 12 pounds

Giraffes have 32 permanent teeth, the same as humans. Their teeth can measure 17 inches long.

A hippo is capable of biting a small boat in half with its sharp, 20 inch-long teeth!

The largest toothed whale is the 70-ton sperm whale. It has from 36 to 60 teeth, all in its lower jaw. Each tooth can be more than eight inches long. The tusk of the male narwhal, an Arctic whale, is more than eight feet long.

Scientists count rings on a dolphin's teeth to find out its age. The long-snouted spinner dolphin has as many as 252 teeth.

Insects have teeth, but they are called fangs or mandibles. Some insects also have teeth in their gizzard to help grind up food.