Types of sharks include the thresher shark, the porbeagle and the swellshark. The thresher shark's distinctive tail is shaped like a thresher. It is mostly found in temperate and tropical oceans. Thresher sharks mature when they're about 10 feet long, though females mature at about 9 feet. The largest thresher shark was about 25 feet long, and the heaviest weighed over 750 pounds.
The porbeagle is a medium-sized shark that can grow to about 12 feet long. It is blue-gray or brown on its dorsal regions and has a white belly and a conical snout. It's found off the coast of eastern North America to depths of 1,200 feet.
The swellshark is a small shark found in the Pacific Ocean off the coast of the United States and South America. It grows to a little over 3 feet long and is notable because it can swell up to twice its size. This mechanism allows it to wedge itself between rocks or crevices and prevent being pulled out by predators such as larger sharks. The swellshark eats crustaceans, bony fish and mollusks and lies in wait at the bottom of the sea till they swim by. The swellshark is also biofluorescent. It is harmless to human beings.