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 Sea turtles are large air-breathing reptiles that inhabit warm waters of the world's oceans, bays and estuaries. They are similar to tortoises and freshwater turtles, except that their legs are actually flippers that aid them in swimming.
Species of sea turtles range in size, shape and color. The olive ridley is usually less than 100 pounds, while the leatherback ranges from 650 to 1,300 pounds.
Sea turtles are closely related to ancient species dating back 130-150 million years to the Cretaceous Period.
Sea turtle shells consist of an upper part (carapace) and a lower section (plastron). Hard scales (or scutes) cover all but the leatherback. Sea turtles are air breathers, but are capable of holding their breath for quite some time. Their streamlined bodies and large flippers make them remarkably adapted to life at sea.
Sea turtles lack teeth, but their jaws have modified beaks, particularly suited to their feeding habits, which for most species include a variety of crustaceans, such as crabs, shrimp, and lobsters. Leatherbacks, however, feed chiefly on jellyfish.
Like other reptiles, sea turtles are cold-blooded, meaning their body temperature depends upon their surroundings. In the Atlantic, this necessitates that the turtles must migrate southward as northern waters cool off in the fall. Unfortunately, some individual turtles wait too long and become stranded in the northern waters and must be rescued.
There are five species of sea turtle in the North Atlantic Ocean - hawksbill, loggerhead, Kemp's ridley, green and leatherback. In the eastern United States 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 roam as far north as Cape Cod near the shore, while the leatherback ranges even further north.
Life Cycle
The life cycle for sea turtles begins in the spring and early summer as the males and females mate in the waters near the nesting beaches. The females come ashore, excavate holes 20-30 inches deep usually in the upper beach near the base of the dunes. They then deposit 80-200 ping-pong ball-sized eggs into the holes. Females may return to the nesting beach to lay up to 10 clutches of eggs in a season (except the Kemp's Ridley).
The eggs incubate in the hot sand for about two months before the tiny hatchlings break through the shell of the egg, usually at night, and scramble out of the nest to head for the water. These hatchlings are prey to many predators, however, and many are snatched up by ghost crabs, dogs, foxes, raccoons, opossums and gulls before they make it to the water. Once at sea, others are lost to predators such as fish and seabirds. It is estimated that less than 1 percent of the hatchlings live to maturity.
Researchers believe that baby turtles spend their earliest years floating around the sea in giant beds of sargasso weeds, where they do little more than eat and grow. Once turtles reach dinner-plate size, they appear at feeding grounds in nearshore waters. They grow slowly and take between 15 and 50 years to reach reproductive maturity, depending on the species. There is no way to determine the age of a sea turtle from its physical appearance. It is theorized that some species can live over 100 years.
Endangered or Threatened Species
Hunting, fishing, development and pollution have seriously reduced sea turtle populations. Development in coastal areas have greatly reduced natural nesting habitats. Capture of adult turtles for eggs, meat, leather, and tortoise shell has decreased breeding populations. Incidental capture of adults in fishing nets and shrimp trawls has brought one species, the Kemp's ridley (Lepidochelys kempi), right to the brink of extinction. For these reasons all species of sea turtle are protected under federal endangered and threatened species legislation.
The above introduction to sea turtles is indebted to materials created by the Caribbean Coastal Conservation Corporation and Sea Turtle Survival League and the Coastal Research and Education Society of Long Island, Inc. For more information on sea turtles, visit the following websites:
Caribbean Coastal Conservation Corporation and Sea Turtle Survival League
http://www.cccturtle.org/contents.htm
Broward County, Florida Sea Turtle Conservation Program
http://www.co.broward.fl.us/bri00600.htm
Coastal Research and Education Society of Long Island, Inc. http://www.cresli.org/cresli/turtles/seaturts.html
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