The blue shark, also known as the great blue shark, is a species of requiem shark in the family Carcharhinidae which inhabits deep waters in the world's temperate and tropical oceans. It is the only living species of genus Prionace. An extinct species, P. clarki, is known from teeth from California of the Late Pliocene. Averaging around 3.1 m (10 ft) and preferring cooler waters, the blue shark migrates long distances, such as from New England to South America. It is listed as Near Threatened by the IUCN.