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All Creatures,

Episode 171: Giant Tortoise of the Galápagos

June 30, 2020

We last visited the legendary Galápagos Islands in Episode 118 with the Marine Iguana. This week we cover the more famous Galápagos Tortoise. Their natural history and conservation story is incredible and should not be missed. Joins us this week as we chat all about this giant and unique reptile.

Galápagos Tortoise History

The earliest turtles known date to the Late Permian Epoch(the Permian Period lasted from 298.9 million to about 251.9 million years ago). The first tortoises date back about 55 million years ago. The giant tortoises lived on every continent, excluding Australia and Antarctica. However, over time these eventually disappeared. The only existing populations of giant tortoise were found on the Galápagos, Seychelles and Mascarenes Islands. Eventually, they went extinct on the Mascarenes Islands due to human hunting.

How the giant tortoise came to inhabit islands is a fascinating one. It is believed these animals were washed out to sea, where they survived for great lengths of time. Eventually landing on islands they established populations. This hypothesis was proven partially correct when in 2004 one of the giant tortoises from Seychelles washed up in Tanzania, which was over 740 km away. The tortoise while emaciated was alive and covered in barnacles.

There are 15 known species of the Galápagos Tortoise, 5 of which are now extinct.

Galápagos Tortoise Physiology

The oldest tortoise- in the world is believed to be Jonathan, an 187-year-old  Seychelles giant tortoise who lives in St Helena. The all-time verified record holder for the world’s oldest tortoise, according to Guinness World Records, is Tu’i Malila, which died in Tonga in 1965 at the age of 189. How these animals survive to such ages has excited scientists for many years. It is believed their slow metabolisms has an affect. Additionally, Lonesome George, the last Pinta Giant Tortoise provided some insight. Scientists sequenced his DNA and found these animals possessed a number of gene variants linked to DNA repair, immune response, and cancer suppression not possessed by shorter-lived vertebrates.

More can be read about Lonesome George and his contribution to science HERE

One of the other fascinating facts about these animals are the different shell types. The Galápagos Tortoise with a saddleback more shell type inhabits the drier and lower elevations. Whereas, those with a domed shell type inhabit the higher elevations.

A fascinating Nature paper on different shell types can be read HERE

You can watch the blow by blow account of a male Giant Tortoise Fight HERE

Conservation

The Galápagos Tortoise was heading swiftly to extinction. However, focused conservation efforts have turned this around and many of the species are recovering. One such story is that of Diego who was one of the last of 15 giant tortoise on the island of Espanola.

His story can be read HERE

Organization

Galapagos Tortoise Movement Ecology Program 

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