The earliest sharks date from more than 420 million years ago, before the time of the dinosaurs! The 400 species of modern sharks have evolved in various ways and scientists have classified them into the 8 major groups shown in this graphic. See how sharks fit into this family tree, from the most well-known sharks like the great white and tiger sharks, to the bizarre lesser-known sharks like the frilled shark, goblin shark and cookiecutter shark.
Most sharks are content to be bottom dwellers. They scavenge the bottom for food at a slow methodical pace. A few predatory sharks have stronger tails that thrust them forward at great speeds to catch their prey. Periodically these sharks breach the surface in a burst of speed.
It may surprise you just how massive some sharks are. The largest shark, the whale shark is 2 feet longer than a typical school bus and weighs more than twice as much! (The average 38? 84 passenger school bus weighs between 22,000-28,000 lbs). Luckily for us and most of the sea creatures out there, the two largest sharks alive today feed mostly on plankton. That makes the Great White the largest predator shark. On the other end of the scale the Dwarf Lanternshark is currently the smallest known shark, reaching only 8.3 inches (21.2cm) in length.