Marine Turtle status Report - Indian Ocean - South-East Asian ...

1. IntroductionTurtles are reptiles of the order Testudines. They have lived on earth for over 200million years. There are three distinct types of turtles: marine turtles which arebig and live in saltwater; terrapins which have webbed feet and live in freshwater;and tortoises which have tough, thick shells and scales, and live on land in dryconditions.Marine turtles dwell in tropical and subtropical seas throughout the world. Theyare partially covered in scales, have streamlined bodies, large paddle-like flippers,lungs that require them to surface frequently for air, and salt glands that helpthem adapt to life in the sea. Unlike their terrestrial and freshwater counterparts,marine turtles are unable to retract their heads and limbs into their shells.Marine turtles are the only widely distributed marine reptiles. Many speciesmigrate for hundreds or even thousands of kilometres among their feeding,mating and nesting grounds. After mating occurs near their nesting grounds, thefemales come ashore to lay their eggs in the sand. Female turtles return to nest onthe same beach on which they were born. Males never return to the beach. Themales mate with several females in the water before returning to their feedinggrounds. All marine turtles begin their lives as tiny hatchlings on land. The sex ofhatchlings is determined by the temperature of the nest where warmer nestsproduce a majority of female hatchlings while cooler nests produce mostly malehatchlings.The scientific classification of marine turtles is described below:Kingdom : AnimaliaPhylum : ChordataClass : ReptiliaOrder : TestudinesSuborder : CryptodiraSuperfamily : Chelonioidea (Bauer, 1893)Family : Cheloniidae (Oppel, 1811): Dermochelyidae: Protostegidae (extinct): Toxochelyidae (extinct): Thalassemyidae (extinct)Today, there are seven extant or existing species of marine turtles; namely, theLeatherback (Dermochelys coriacea) (Family Dermochelydae), Loggerhead(Caretta caretta), Flatback (Natator depressus), Olive Ridley (Lepidochelysolivacea), Kemp’s Ridley (Lepidochelys kempi), Hawksbill (Eretmochelysimbricata) and Green turtle (Chelonia mydas) (all in the family Cheloniidae). Aneighth species, the Black turtle (Chelonia agassizii), is currently a subject ofdebate among biologists (Pilcher, 2001).1