Sea turtles are large turtles that inhabit warm waters of our planet's oceans, bays and estuaries. They are similar to their terrestrial (land) cousins, the tortoises, and to freshwater turtles, except that their legs have been modified into flippers to aid them in swimming. Their shape has taken on a flattened, more streamlined appearance - tapering off in the rear to allow for less water resistance during swimming. All sea turtles except the leatherback turtle have a hard carapace (top shell) and another hard shell on the belly called the plastron. The carapace, as with all other turtles incorporates their backbone, sternum and ribs. This is unlike most other animals whose backbone and ribs are free of a shell or skin.

Sea turtles are closely related to ancient species dating back 130 million years to the Cretaceous Period. Some may be more closely related to dinosaurs than our present day reptiles.

Like all other reptiles, sea turtles' body temperature depends upon their surroundings which explains their migration southward as northern waters cool off in the fall. The leatherback turtle, though, has recently been found to be able to create some body heat, thus making them able to withstand the chilly waters off Canada and Iceland, where they roam in the summer. Sea Turtles are air breathers, but are capable of holding their breath for quite some time. It is thought that they are also able to absorb oxygen from their skin, mouth and their cloaca.

Sea turtles remain in the sea during their entire lives except for adult females who briefly come ashore to nest in the summer months. In the eastern US sea turtles are found mainly along the southern and Mid - Atlantic coasts, Gulf of Mexico and in the Caribbean Sea. During the summer months when the Gulf Stream carries warm water north as far as Canada, sea turtles, with the exception of the hawksbill, roam as far north as Cape Cod near the shore, while the leatherback ranges even further north.

There are five species of sea turtle in the North Atlantic Ocean - hawksbill, loggerhead, Kemp's ridley, green and leatherback Of these, the last four regularly inhabit Long Island's waters.

LIFE HISTORY

All sea turtles have a similar life history. Life begins as the males and females mate in spring and early summer in the waters near the nesting beaches. The females come ashore and deposit 80 - 200 ping pong ball-sized eggs in a thick fluid in the 20 - 30 inch deep holes they excavate. The nest is located in the sand on the upper part of the beach, often at the base of the dunes or vegetation line. Females may return to the nesting beach to lay up to 10 clutches of eggs in a season (except the Kemp's Ridley).

After the hot sand incubates the eggs for about two months the tiny hatchlings break through the leathery shell of the egg and scramble out of the nest to head for the water. Although this usually occurs at night, these tiny creatures are prey to many predators such as ghost crabs, dogs, foxes, raccoons, opossums and gulls. If they make it to the sea another set of predators, fish and seabirds, are waiting to pick them off. It is estimated that only a fraction of turtles that hatch actually survive this gauntlet, and less than 1% endure to maturity. Once in the sea, the turtles will inhabit offshore waters of the Atlantic Ocean and the Gulf of Mexico. They remain there for several years, sometimes taking refuge in large clumps of Sargassum weed that host a variety of small fishes and crustaceans which presumably the turtles feed on.

After two to three years loggerheads, greens and Kemp's Ridleys move into coastal waters in their northern range, where they spend their juvenile life. Locally, these three species of turtles can be found in Long Island Sound and Long Island's eastern bays where they feed on crustaceans (crabs, shrimp, lobster, etc.), shellfish and even small fish. They arrive here every year in late June as water temperatures rise, then migrate south to warmer waters by late fall.

Leatherbacks lead a different lifestyle. They appear to inhabit deep oceanic waters for most of their life feeding on jellyfish, which make up their chief diet. Adult and sub - adult leatherback turtles are found in Long Island's offshore waters.