There are seven kinds of sea turtles: green, flatback, hawksbill, loggerhead, Atlantic ridley, Pacific ridley, and the leatherback.  The sea turtles live in the warm ocean waters, though sometimes the leatherback will venture into the cold waters of Canada.  Sea turtles like their life in their shell.  Their shells are lighter than those of land or swamp turtles.  Sea turtles are some of the largest species to inhabit the oceans.  They range in size from 28 inches and weighing 100 pounds to 8 feet weighing 1,500 pounds.  Sea turtles have flippers instead of legs.  The large head of the sea turtle cannot be pulled back into the shell, though a few of the species can pull their heads back a little by bending their necks back.  Once a sea turtle enters the ocean waters it does not leave.  The only reason a female leaves is to lay her eggs.  A female may travel thousands of miles to the beaches where the eggs are laid and then buried.  Sea turtles are helpless when they are on land.  When the eggs hatch the baby turtles make a journey across the beach to the water.