These animals always strike me as wonderfully implausible, holdovers from the Cretaceous period reappearing after millions of years. These tortoises are of the genus Geochelone, and several centuries ago they could be found on many isolated islands, including Mauritius, Rodrigues and the Seychelles. The ability of these animals to withstand long periods of drought and starvation, the very thing that allowed their success on these islands, unfortunately turned into their downfall. They became a perfect source of fresh meat for sailors, away from home for years at a time, and until then forced to rely on salted and dried meats. They could be stored by the hundreds in the hulls of passing ships, and provide endless tasty nutrition. As a result of this, the only remaining wild populations of giant tortoises are on Aldabra near the Seychelles, and the Galapagos.
The Galapagos tortoises originally descended from a much smaller animal, a Chilean desert tortoise that had somehow floated or rafted its way to the isolation of its new home. Gigantism is a common trait in islands, and can bring many advantages to the animal involved, such as better fat and water storage, better survival through hungry times, diminished heat loss and a better ability to throw its weight around decisively in competitive interactions with others of its own species.
Geochelone elephantopus, the Galapagos giant tortoise, spread to several islands, and became isolated, thus giving rise to several separate subspecies, of which eleven remain to this day. In general, those found on the larger islands fared a lot better than those on smaller islands did, as they were pretty much out of reach. Santa Cruz Island has a relatively healthy population, around 2000-3000 individuals, which can easily be seen during this time of the year. They particularly enjoy the many pastures of the highlands, and can often be found wallowing in mud pools such as the one in the picture, much to the astonishment of onlookers such as the vermilion flycatcher.
