There’s a new tortoise in town, and this one is a giant! The Aldabra giant tortoise is one of the largest tortoises in the world, and it comes from the Aldabra Atoll in the Seychelles, in the western Indian Ocean.
Big, Friendly, and Bred
The Aldabrachelys gigantea has a huge domed shell that acts as armor to protect its otherwise soft and vulnerable body. It has a long neck that allows it to tear leaves from trees, and thick, short legs with flat feet that help it traverse the sand. Its carapace usually grows around 3 to 4 feet in length, and can weigh up to five hundred and fifty pounds.
“They are very friendly because they are captive bred,” says Jimi Lim of Congo Charlie Exotic Reptile Jungle and Advanced Hobbyist Genetic Breeding Station, Inc., which only breeds Department of Environment and Natural Resources (DENR) wildlife-registered reptiles. “They are quite accustomed to seeing humans, so imagine a few boulder sized tortoises coming towards you to get the bananas you are holding.
These guys will grow up to a meter—even more for the males. The males are much larger than the females. I think the males’ size are a significant factor in the mating process of the species.”
Jimi first got introduced to breeding Aldabra giant tortoises through friends, and he quickly fell in love with the gentle giants because of their friendliness and their size. “We managed to import a trio of [second-generation captive bred] adult Aldabras directly from Africa, and we made sure through the DENR-Protected Areas and Wildlife Bureau (PAWB) that we had the necessary documents, and we made sure that the suppliers also have the complete legitimate papers.”
And although Aldabra giant tortoises are usually cautious and slow, they have surprising speed when sprinting, especially when they smell a treat. “They have a huge appetite,” says Jimi. “We usually give them grass and fiber-rich greens; that’s their basic food. But we occasionally give them fruits, too. Bananas, papayas, watermelons, and cantaloupes… just peel one of these fruits and you’ll see how they react when they smell them.”
In the wild, Aldabra tortoises will eat grass, leaves, plants, and weeds. In fact, there is a particular habitat that has coevolved with the Aldabra giant tortoise, called “tortoise turf,” which is made up of over twenty species of grasses and herbs that are naturally dwarfed by the constant grazing pressure of the feeding tortoises. Although Aldabra giant tortoises are herbivores, they will occasionally also eat insects and carrion, even the bodies of other dead tortoises, in order to get obtain a little protein. They also need the right balance of calcium and phosphorus in their diet to maintain their enormous domed shells.
Jimi explains, “[With] most tortoises, the challenge is keeping their carapace perfect. No pyramiding. We’d like to avoid too much protein for our tortoises. Tortoises in the wild get animal protein from carcasses; the exact amount [they need] to have is still debatable, but I can say that they still need it. They need calcium and vitamin D, with the right ratio of phosphorus to metabolize and have enough minerals for their bones.” The Aldabra giant tortoise is also well-suited for the tropics. “One thing I liked about these tortoises when I first saw them was that they were waddling in mud, like carabaos, so they are used to the humidity and weather in a place like ours.”
The Place of Origin: Aldabra
Uninhabited and isolated, over 400 kilometers northwest from Madagascar, Aldabra Atoll is the world second largest coral atoll, or ring shaped coral reef, the largest being Kiritimati Atoll, or Christmas Island. Aldabra Atoll has the largest population of giant tortoises in the world, numbering about 100,000 individual animals. It is composed of four islands around a large shallow lagoon and encircled by fringing coral reef.
It was designated by UNESCO as a World Heritage Site in 1982, and was described by Sir David Attenborough as “One of the wonders of the world” and a “crown jewel” of the Indian Ocean. BirdLife International also declared Aldabra as an Important Bird Area in 2001. Aldabra hosts the Aldabra rail, the only surviving flightless rail species in the Indian Ocean.
Tortoises vs. Turtles
What’s the difference? Both are shelled reptiles, but there are major differences between tortoises and turtles, the biggest of which is that tortoises are land-dwellers, while turtles live in the water some or nearly all of the time. Tortoises have heavy, large, dome-shaped shells that are either black, brown, or tan, to protect them from land predators.
Turtles have flatter, more streamlined shells that can be green, black, or yellow; these are lighter to prevent the animal from sinking in water and to increase their swimming speed. Tortoises have round, almost flat feet that they use for digging, while turtles have webbed feet or flippers with long claws, good for gripping and swimming.
Common turtles generally live between 20-40 years, while sea turtles average 60-70 years. Tortoises, on the other hand, are among the longest-lived animals on Earth, with some individuals like Adwaita thought to be over 200 years of age at the time of his death. Esmeralda, another Aldabra giant tortoise, is 170 years old and is the second-oldest living giant tortoise in the world, after Jonathan, a Seychelles giant tortoise who is 182 years old.
No, this isn’t some sort of network marketing deal for tortoises, but a real problem for tortoise lovers who want to maintain that round, domed shell. ‘Pyramiding’ is a form of metabolic bone disease in tortoises that causes the keratin to pile up on the scutes (bony external plates or horn) on the tortoise’s shell, forming little ‘pyramids’ that sound hollow when you tap them. In advanced cases of pyramiding, the shell itself can become soft and flatten out.
Pyramiding can be caused by a dietary imbalance, either from too much protein (causing the keratin buildup), or too little calcium, or too much phosphorous, or not enough Vitamin D3, which can impair bone development in the shell, causing it to become soft. Lack of exercise can also cause a buildup of protein. In the wild, a tortoise must walk miles while foraging for food, and they need more protein the more exercise they get.
Exercise speeds up metabolism and causes healthy deposition of calcium in the bones. Water is also very important, not just for drinking but also humidity. A tortoise kept at higher humidity levels is less likely to show pyramiding than those kept in arid conditions, despite being placed on a high protein diet.
Preserving a Gentle Giant
The Aldabra Giant Tortoise is listed as an animal that is “Vulnerable” to extinction in the wild on the International Union for Conservation of Nature or IUCN Red List of Threatened Species, because of the effects of human activity. The tortoises and their eggs were particularly easy for early settlers of the island in the 1700s to hunt and good to eat, and within 100 years they were nearly wiped out.
On the other hand, the Aldabra giant tortoise has also been the beneficiary of organized conservation since the 19th century, and tortoises bred and raised in captivity have lived long lives. “With the proper care and conditions, they can surely outlive us,” says Jimi. “I think eating a lot of greens truly does wonders.” Some individual Aldabra giant tortoises are believed to be over 200 years of age, outliving their original human caretakers.
Adwaita (which means “unique” in Sanskrit), was a male Aldabra giant tortoise from Kolkata, India, who was reportedly given to Robert Clive of the East India Company in the mid-1700s. He was transferred to the Alipore Zoo in Kolkata around 1875, and lived there until his death in 2006, which would have made him around two hundred and fifty years old! “Our facilities primary purpose is breeding,” says Jimi, “and we select captive-bred specimens, because they are hardier and we can be assured of their breeding and lineage. There are only a few groups of breeders that can supply F2 to F4 specimens – that is, second to fourth generation captive bred Aldabras.
Since I am already in my prime, I selected adult specimens so that I could breed them as soon as I got them. My adults are even older than my children!” Outdoors is the best place to house Aldabra tortoises. The hatchlings can be housed indoors till they reach 2 years, but then they’ll need all the space they can get to roam. “The larger the enclosure, the better,” says Jimi. “They wander a lot, and during perfect weather days they’ll walk the whole time if possible. We want to keep their carapace scratch free, so we try to put them in large enclosures, to prevent them from scratching their carapace on the cement dividers. During the stormy or cold months, it’s best to provide them heat lamps.”
Tortoises require a body temperature of 80-90°F to properly digest their food. Being cold-blooded, if the tortoises are kept too cool, they will still eat and remain active, but they won’t be able to properly digest their food and absorb nutrients, especially calcium for their bones and shells.Despite being reptiles, Jimi assures us that Aldabra giant tortoises, especially captive bred individuals, are not dull, emotionless creatures.
“Yes, they are very friendly. Especially if they can smell you holding some of their favorite fruit, you can touch them, and they can feel it even through the carapace. But they most especially like it when you rub them under their chin!” He added that tortoises are like elephants with shells, and just like elephants, tortoises have good memories too. “I can say that they remember people,” says Jimi. “They remember us. There was this one time that my adult male had a problem, an internal one. It didn’t eat for at least a month. I personally oversaw his daily feeding, medication, and soaking. I even talked to him at times, and I think it made a difference. He slowly got back his weight, ate a few bananas, and even began eating his chili leaves by himself. So yes, I think they can show emotion.”
“They may seem dull in appareance, they might even look mean,” he adds, “maybe because they’re dark? Or because they’re huge? You have to look into their eyes. When you come face to face with an adult Aldabra, that’s how you’ll fall in love with it. That’s how you’ll get to understand how they are. Try to interact with them. We at Congo Charlie welcome the people who might want to see if these are the tortoises for them.”
This appeared as “The Shell Game” in Animal Scene’s October 2015 issue.