Giant Tortoises

by Todd Metcalfe

Land Tortoises

Giant Tortoises (Geochelone elephantopus) are the largest of the naturally occurring land animals in the Galápagos. They can grow to weigh 250 kg (550 lbs). There are no reliable records of how long the tortoises can live as of yet, because they can far out live humans. There are reports of some of these animals living about 200 years. Part of the reason why these animals can live so long is because they have such a slow metabolism. Ironically, this is also part of the reason why their populations have declined so much. The Galápagos tortoises can live up to a year without food or water. This made them a great food source for many of the ships that visited the islands in the 1800s. The sailors would collect the tortoises and keep them alive on board to serve as a source of fresh meat while at sea. This slow metabolism also means that the tortoises do not digest their food well, as is evidenced by their droppings. The leaves are not very well digested and are mostly still intact. Click here to see picture.

At one time there were at least 14 different sub-species of giant tortoise, all of these are believed to be derived from one single parent species. However, today only 11 sub-species remain. And one of those species, the tortoises of Pinta, has only one known living member, Lonesome George (perhaps the most famous of all turtles). The main distinguishing feature between the different species is the shape of their shells. There are two main shapes domed, and saddle-backed. The saddle-backed variant is the reason for the name of the Archipelago: "galápagos" means "saddle" in Spanish.
A Saddle-backed turtle is present in the picture above, click here to see a domed tortoise.

Turtles have declined due to direct hunting by man and from predation on younger turtles by introduced animals. Until the tortoises are about 5 years old, rats and other introduced animals are able to prey upon them. To help preserve the turtles there has been a breeding campaign launched by the Darwin Research station.

At the Darwin center our group saw some of the young turtles, click here to see them.

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