Scientific Name                             Aldabrachelys gigantea

Conservation Status                    Vulnerable

Appearance

Giant tortoises are most noticeable due to their large domed shell. This acts as protection against predators as their body is quite soft. Their neck is elongated allowing them to reach up and tear leaves from branches. Their leaves are short and round with almost flat feet. These assist them when they are walking across sand. Their skin is a black or brown colour and the shell is brown.

Males reach lengths up to 1.1m while females are slightly smaller at 0.9m long. Their weight ranges between 150 and 250kg (330-550lbs).

aldabra giant tortoise

Lifespan                                                                                  

Some tortoises are reputed to be over 200 years old but is difficult to verify as their human companions often outlive them. Currently the oldest verifiable Aldabran giant tortoise is said to be 170 years old.

Diet

Aldabra giant tortoises are herbivorous animals. They feed upon grasses, leaves and woody plant stems. They will eat these food items even if they have dried out. Some evidence suggests that on occasion they take some carrion. In Some instances they may even eat another tortoise.

The shell adapts to the tortoises environment. Those in habitats where most of the food is on the ground have a shell which comes down over the neck and it is more dome shaped. Those where food is taken from the trees have a shell with a raised front and flattened top allowing the neck to extend up.

Fresh water is at a premium in tortoise habitat. This means most of their moisture is taken from their food.

Habitat

The Aldabra Giant Tortoise is found mostly on the Aldabra Atoll which is part of the Seychelles Island chain which is in the Indian Ocean. Populations also exist on Mauritius and Rodrigues along with a colony on Changuu Island near Zanzibar.

They reside in low scrub, grasslands, mangrove swamps and coastal dunes. Large concentrations of tortoises occur in grasslands known as platins. They will wander into sparse rocky areas when food is scarce but most of the time they live in vegetated areas.

aldabra giant tortoise

Reproduction

Breeding begins in February and ends in May. The eggs are carried by the female for ten weeks.

Nine to twenty-five eggs with a rubbery shell are deposited into a dry and shallow nest which the female will dig. On average about half of the eggs are fertile. Females able to produce two clutches of eggs in a year. This depends on how many tortoises live in an area. Areas with less tortoises have females which produce less eggs.

It takes eight months of incubation before the eggs hatch. This means they will emerge from their eggs between October and December.

Maturity is not reached until somewhere between 20 and 30 years of age for this species.

Behavior

These animals vary between being solitary and roaming in herds.

Most of their activity occurs in the morning. This is when they go browsing for food aiming to avoid warm temperatures. During the day they may dig underground or rest in a puddle of water.

Predators include dogs and goats who eat the tortoises along with their food. A species of giant crab living on the island is said to feed upon the young crabs. Climate change is posing a large threat to this species.

Quick facts

Aldabra giant tortoises appear to have no fear of humans which is part of the reason settlers were able to hunt them so easily.

They were referred to as the ‘ninjas’ of the tortoise world by Mexican biologist Jose Antonio de Alzate y Rammirez. This is due to the perilous acrobatic acts they undertake to reach low hanging branches.

Their used to be 18 tortoise species living in the Indian ocean with all but the Aldabras were hunted to extinction by sailors along with the rats, cats and pigs that they brought to the islands.

Photo Credits:

Top        – By Muhammad Mahdi Karim (www.micro2macro.net) (Own work) [GFDL 1.2 (http://www.gnu.org/licenses/old-licenses/fdl-1.2.html)], via Wikimedia Commons

Bottom – By Ltshears (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

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