Star of animal documentaries, the giant tortoise of the Galapagos is an emblematic reptile in more than one way. First by its span – the record weight stands at 422 kg – then by its longevity : up to two centuries of life! Portrait of an old lady with a placid temperament.
Galapagos Giant Tortoise Identity Card
The giant Galapagos tortoise (Chelonoidis nigra), also called a turtle elephantine – because of its huge legs – is a species of reptile belonging to the family of testudinidae. The animal forms a genus subdivided into ten species so closely related that many scientists consider them to be subspecies of Chelonoidis nigra. Largest land turtle in the world, it measures 1.50 to 2.20 m long on average. Males, particularly massive and heavy, weigh up to 250 kg against around 50 kg for females.
Galapagos giant tortoise: scales and thorns
The Galapagos giant tortoise has a large, thick shell made up of large scales while the back and ventral face have smaller scales. Like all of its body, its breastplate displays a color gray to green with black highlights. The reptile sports a large head, a sharp beak, a powerful jaw, a long neck, a short tail and large legs with strong claws. The male is adorned with a concave plastron (flat in the female) and its dorsal crest with solids thorns is more imposing.
Nine islands for the Galapagos giant tortoise
The Galapagos giant tortoise is endemic of the Galapagos archipelago, (Equateur province), in the Pacific Ocean. Each of the subspecies lives in one of the nine islands of the archipelago where it frequents the semi-open, dry and shrub savannas and clear tropical forests. Most of the year, the reptile occupies the humid uplands and flanks of volcanoes where the night temperature sometimes drops to -10 ° C. In the rainy season, the Galapagos giant tortoise migrates to the plains at the foot of the mountains to graze the tender grass.
The giant Galapagos tortoise, fond of fruit
Herbivorous and frugivorous, the Galapagos giant tortoise eats almost every plants that dot its path. Its menu consists mainly of herbs, leaves, lichens, ferns, aquatic plants, berries, fruits wild (guavas, melons, oranges, bananas, apples, grapes…). Devoid of teeth, it cuts food using its sharp beak. To hydrate, the giant Galapagos tortoise drinks dew and plant sap but is able to survive for month without drinking. For this, she transforms the fat located under its shell in water. However, if she finds a pool or stream, she will drink quickly and heavily, storing water in her bladder and neck.
Mud bath for the giant Galapagos tortoise
Animal to cold blood, the reptile regulates its body heat (between 25 and 30 ° C) according to the ambient temperature. Thus, the Galapagos giant tortoise usually activates the morning and in the evening then rest in the shade and costs the afternoon. With a very heavy shell and short legs, the animal moves slowly, at a speed average less than 0.50 km / h. He stops to eat, rest or bathe. The giant Galapagos tortoise thus offers itself mud baths or lie down in shallow water in order to thermoregulate and get rid of parasites, like ticks.
Male fight in the Galapagos giant tortoise
This gregarious animal lives mostly in group comprising 20 to 30 individuals of all ages. Gatherings are especially frequent during the migration period. However, in the mating season, violent fights can occur between males during which rivals attempt to bite the head and neck. In reality, unfinished shots are more a matter of attempts tointimidation than a real intention to hurt. An opponent who finds himself on his back plays his life because his organs will press on his lungs and prevent him from breathing. It will then have to vigorously shake its paws to rock its shell and turn around as quickly as possible. The loser will admit his defeat by leaving the head down.
Galapagos giant tortoise: incubation in the sand
The Galapagos giant tortoise breeds year round with a peak observed between January and August. After mating, the female migrates to areas sandy, near the coast. To build the nest, she chooses a place sunny and digs the ground with its hind legs. Between 2 and 15 eggs are deposited in the hole about 30 cm deep, which the female will then cement with a mud of earth and its urine. When dry, this mud cover will protect the spawn from dehydration and predators. The incubation period lasts from 120 to 240 days, depending on climatic conditions. Namely that the internal temperature of the nest determines the sex of the embryo.
Tiny giant Galapagos tortoises
When hatched, these future giants are completely black and tiny : their weight varies from 80 to 150 gr for a size that can reach 60 mm. Some will put a month to unearth oneself and finally get to know the open air. Abandoned by their parents who have resumed their daily activities, newborns must show themselves autonomous, fend for themselves to support themselves and join the adults in the highlands. At this point in their life, the little ones are very vulnerable facing predators. Their growth is rapid: they reach nearly 70 cm at 18 months and exceed 1 m around 3 years. Then development slows down and the juveniles reach their sexual maturity between 20 and 25 years old.
The giant Galapagos tortoise, more than a century old
If the adult turtle does not know no enemy, the young and the eggs fall prey to the nozzle Galapagos (the only natural predator) as well as animals introduced by humans: dogs, cats, pigs and rats. The reptile has long been used as a food resource both abundant and easily accessible by sailors and islanders. When they were discovered in the XVIe century, its numbers were estimated at 250,000 individuals against 15,000 Nowadays. The loss and degradation of its habitat (tourism, climate change) are among the main threat weighing today on the animal. The species is endangered and subspecies are already extinct like Chelonoidis abingdonii. Through programs of preservation, the global population of Galapagos giant tortoises is currently increasing. The life expectancy of this iconic reptile is 150 to 200 years wild.