Sea Turtles Sea turtles, also known as marine turtles, belong to the superfamily Chelonioidea. They are reptiles classified under the order Testudines and the suborder Cryptodira. Related Articles: A Guide to British Native Snakes and LizardsGreat White Shark (Carcharodon carcharias) Species Guide: Appearance, Diet, Habitat, Behavior, Stats, And Conservation Status