Aldabra giant tortoise

Template:Taxobox begin Template:Taxobox image Template:Taxobox begin placement Template:Taxobox regnum entry Template:Taxobox phylum entry Template:Taxobox classis entry Template:Taxobox ordo entry Template:Taxobox familia entry Template:Taxobox genus entry Template:Taxobox species entry Template:Taxobox end placement Template:Taxobox section binomial Template:Taxobox end The Aldabra Giant Tortoise ('geochelone gigantea') is one of the largest tortoises in the world. Similar in size to the famous Galapagos Giant Tortoise, its carapace averages 120 cm in length. The average weight of a male is around 250 kg, but one male at the Fort Worth, Texas zoo weighs over 360 kg.

Physical Characteristics

The shell is a dark gray or black color with a high domed shape. It has stocky, heavily scaled legs to support its heavy body. The neck of the Aldabra Giant Tortoise is very long, even for its great size, which helps the animal to exploit tree branches up to a meter from the ground as a food source.

Females are generally smaller than males, with average specimens measuring about 90 cm in length and weighing around 150 kg.

Diet

Primarily herbivores, Aldabra Tortoises will eat grasses, leaves, and woody plant stems. They occasionally indulge in small invertebrates and carrion, even eating the bodies of other dead tortoises. In captivity, Aldabra Giant Tortoises are known to enjoy fruits such as apples and bananas as well as compressed vegetable pellets.

There is little fresh water available for drinking in the tortioses' natural habitat, therefore they obtain most of their mositure from their food.

Breeding

Aldabra Giant Tortoises reach sexual maturity when they attain about half their final size. Interestingly, it seems that reaching sexual maturity is determined by size, not by age.

After mating from February to May, Females lay between 9 and 25 rubbery eggs in a shallow, dry nest. Usually, less than half of the eggs are fertile. Females can produce multiple clutches of eggs in a year. After incubating for about 8 months, the tiny, independent young hatch between October and December.

Range and Habitat

The main population of the Aldabra Giant Tortoise resides on the islands of the Aldabra Atoll in the Seychelles. Another group of the animals resides on the island of Zanzibar. The tortoises exploit many different kinds of habitat including grasslands, low scrub, mangrove swamps, and coastal dunes.

A peculiar kind of habitat has evolved due to the pressures of the tortoises: "tortoise turf," a comingling of 21 species of grasses and herbs. Many of these distinct plants are natually dwarfed and grow their seeds not from the tops of the plants, but closer to the ground to avoid the tortoises' close cropping jaws.

As the largest animal in its environment, the Aldabra Tortoise performs a role similar to that of the elephant. Their vigorous search for food fells trees and creates pathways used by other animals.

Behavior

Aldabra tortoises are found both individually and in herds, which tend to gather mostly on open grasslands. They are most active in the mornings when they spend time browsing for food. They dig underground burrows or rest in swamps to keep cool during the heat of the day.

While they are characteristically slow and cautious, they are capable of appreciable speed, especially when tempted with a treat. They are also known to attempt perilous acrobatic feats, rising percariously on their hind legs to reach low branches. This risks death by tipping onto their backs and being unable to right themselves.

They are also excellent swimmers, being neutrally bouyant. This allowed the spread and eventual speciation of many kinds of related (and now extinct) tortoises across the Indian Ocean

Life Span

Large tortoises are among the longest-lived animals on the planet. Some individual Aldabra Giant Tortoises are thought to be over 100 years of age, but this is difficult to verify because they tend to outlive their human observers.

Conservation

The Aldabra Giant Tortoise has an unusually long history of organized conservation. No less a figure than Charles Darwin worked with the government of Mauritius to establish a preserve at the end of the 19th century.