Shark is the naming term of all members of Selachimorpha suborder in the subclass Elasmobranchii, in the class Chondrichthyes. The Elasmobranchii also include rays and skates; the Chondrichthyes also include Chimaeras. The first shark-like chondrichthyans appeared in the oceans 430 million years ago,[1] developing into the crown group of sharks by the Early Jurassic.[2]
Listed below are extant species of shark. Sharks are spread across 512 described and 23 undescribed species in eight orders. The families and genera within the orders are listed in alphabetical order. Also included is a field guide to place sharks into the correct order.
