2 Families of sea turtles are recognized today

Family CheloniidaeThis family includes all sea turtles with horny plates called scutes that are covering their shells. There are six species in the Cheloniidae family: The Loggerhead, Hawksbill, Flatback, Olive Ridley, Kemp’s Ridley and the Green Sea turtle. The Black sea turtle are by many considered as a subspecies under the Green Sea turtle.

Family Dermochelyidae
These turtles are scuteless. Today there’s only one sea turtle left in this family: The Letherback. Instead of scutes the Leatherback is covered with a leathery skin. Furthermore it’s the only sea turtle whose backbone is not attached to the inside of its shell.