Saturday, March 5, 2011

Pitcairn Island - Green Turtles on Henderson Island

Chelonia mydas, commonly known as the Green turtle, is a large sea turtle belonging to the family Cheloniidae. The range of the species extends throughout tropical and sub tropical seas with two distinct populations in the Atlantic and Pacific. With a flattened body, a beaked head at the end of a short neck, and paddle-like arms well adapted for swimming, it derives its common name from the green fat underneath its shell. Adults are known to grow to 1.5 m long and the average weight of mature individuals is around 200 kilograms. Males are larger than females and neither can pull their heads inside their shells. The carapace of the turtle is known to have various colour patterns that change over time. Hatchlings are mostly black, while juveniles are dark brown and adults are entirely brown, spotted or marbled. Sea turtles spend almost all their lives submerged but must breathe air for the oxygen. With a single exhalation and rapid inhalation, sea turtles can quickly replace the air in their lungs. They can rest or sleep underwater for several hours at a time, but submergence time is much shorter while diving for food or to escape predators as their breath-holding ability is affected by activity and stress. Although their habitat is the sea, Pacific green turtles are known to crawl onto secluded beaches during the day to bask in the sun. The ecology of Chelonia mydas changes drastically with each succeeding stage of its life history. For instance, newly emerged hatchlings are carnivorous and pelagic (ocean going), while immature juveniles and adult turtles are commonly found in sea-grass meadows closer inshore as herbivorous grazers. Gowri gave this minisheet to me.

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