Those which live on land are called tortoise (photo 1) and those which live in sea, rivers or ponds are called turtle (photo 2) by the zoologists. Both are different species. Turtles have broad legs which serve as flippers. A species of sea turtles known as leatherback can weigh up to 800 kilograms, but can attain speed of 35 kilometers per hour. And there is none which can match in deep diving. A biologist named Dr. Scott Eckert carried out an experiment in 1987 to ascertain the depth up to which a leatherback turtle could dive. He tied a pressure gauge on a leatherback and after securing the turtle with a thin wire released it in the sea near Virgin Island of the West Indies. This turtle descended up to a depth of 1,200 meters (3,973 feet). The bodies of giant leatherback turtles contain large amount of fat. No museum displays dead body of such a turtle because the fat in its body keeps on dripping for almost fifty years, filling the entire museum with its stink. Fresh water turtles, on the other hand, are not large. They measure 1.5 to 2 feet maximum in length and 63 kilograms (140 pounds) maximum in weight.
Land-dwelling tortoises, unlike aquatic turtles have short legs of uniform thickness. Not being agile, they are helpless against predators. However, large sized species of tortoise have found safe habitat on remote islands like Galapagos, Aldabra, Seychelles and Mauritius where there are no animals to prey upon them. The largest (250-300 kilograms) tortoises inhabit the Indian’s Ocean island Aldabra and they enjoy longevity of 150 years.