The size of a shark depends on its species. The largest living shark, the whale shark, averages 31.82 feet long. The extinct megalodon was even bigger at about 60 feet long. The smallest shark is the dwarf lanternshark, which is only 6.7 inches long.
There are over 470 species of living sharks. Their primary habitat is the oceans, though bull sharks and river sharks can live in fresh water. Most sharks are carnivorous, but some species feed on plankton. Some shark species hunt in packs and feed cooperatively. Sharks are capable of learning and have been observed investigating novel objects and engaging in play.