Andy Rouse / Galapagos giant tortoise (Geochelone elephantopus / nigra) adult feeding, Santa Cruz, Galapagos

Cheryl-Samantha Owen / Aldabra giant tortoise (Geochelone gigantea) on beach at dusk, Aldabra Atoll, Seychelles, Indian Ocean

Roland Seitre / Childres with African spurred tortoise (Centrochelys / Geochelone sulcata) Dakar, Senegal, West Africa, Vulnerable species. Three newly hatched babies and one adult over 100 years old

Roland Seitre / Antoine Cadi, scientist, and assistant measure the shell of an African spurred tortoise (Centrochelys / Geochelone sulcata) Sahel desert, Ferlo North Reserve, Senegal, West Africa, Vulnerable species....

Roland Seitre / African spurred tortoise (Centrochelys / Geochelone sulcata) Sahel desert, Ferlo North Reserve, Senegal, West Africa, Vulnerable species

Pete Oxford / Saddleback form of Galapagos Giant Tortoise (Chelonoidis nigra) walking, Wolf Volcano, Isabela Island, Galapagos

Thomas Rabeil / Portrait of a Spurred Tortoise (Geochelone sulcata). Termit Massif, Niger, Africa.

Pete Oxford / Galapagos Giant Tortoise (Geochelone elephantophus / Chelonoidis nigra) head portrait, Charles Darwin Research Station. Puerto Ayora,Santa Cruz Island, Galapagos, endemic

Inaki Relanzon / Ploughshare / Angonoka tortoise (Geochelone yniphora), one of the most endangered turtles in the world, Baie de Baly National Park, North west Madagascar.

Albert Lleal / Red-footed Tortoise (Geochelone carbonaria), native to South America

Juan Carlos Munoz / Galapagos giant tortoise {Geochelone elephantopus} cooling in water, Santa Cruz Island, Galapagos, January

Juan Carlos Munoz / Galapagos giant tortoise {Geochelone elephantopus} head portrait, Santa Cruz Island, Galpagos, January

Pete Oxford / Galapagos Giant Tortoise (Geochelone elephantophus vandenburghi) near fumaroles, Alcedo Volcano crater floor, Isabela Island, Galapagos Islands

Pete Oxford / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi), Alcedo Volcano crater floor, Isabella Island, Galapagos Islands, Ecuador

Tim Laman / Galapagos giant tortoise (Geochelone nigra / Geochelone elephantopus) feeding (captive). Charles Darwin Research Station, Santa Cruz Island, Galapagos Islands.

MORLEY READ / "Lonesome George", the last Galapagos Tortoise {Geochelone elephantopus} from Pinta Island, Galapagos

Pete Oxford / Giant tortoise {Geochelone elephantopus}, Alcedo Volcano, Isabela Island, Galapagos

Pete Oxford / Giant Tortoise (Geochelone elephantopus) and tourists in the Galapagos Islands

Peter Blackwell / Leopard tortoise portrait {Geochelone pardalis} Amboseli NP, Kenya, East Africa

Pete Oxford / Red footed tortoise withdrawn inside its shell {Geochelone carbonaria}, Iwokrama Reserve, Guyana

Mark Moffett / Galapagos Giant Tortoise (Chelonoidis nigra) in Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Michio Hoshino / Galapagos Giant Tortoise (Chelonoidis nigra) pair communicating, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) yawning, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) large male on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Pinta Island Galapagos Tortoise (Chelonoidis nigra abingdoni), Lonesome George, the last survivor of his race, Darwin Reserve Station, Santa Cruz Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) group wallowing in seasonal pool on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) with Galapagos Hawk (Buteo galapagoensis) perched on back, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) group wallowing in seasonal pond on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) juvenile with flowers, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Mitsuaki Iwago / Galapagos Giant Tortoise (Chelonoidis nigra) pair and thermal vents, Galapagos Islands, Ecuador

Tui De Roy / Saddleback Galapagos Tortoise (Chelonoidis nigra hoodensis) old male portrait, Pinzon Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) Galapagos Hawk (Buteo galapagoensis) riding on back, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) old male in dry season on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) wallowing in temporary rainy season pool, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Pete Oxford / D - Galapagos Giant tortoise portrait - Dome form {Geochelone elephantopus} retreating into shell. Darwin Research Station. Santa Cruz Is. Galapagos Islands, Ecuador. South America

Pete Oxford / Galapagos Giant tortoise close up portrait - dome form {Geochelone elephantopus} retreating into shell. Galapagos Is

Pete Oxford / Galapagos Giant tortoise portrait {Geochelone elephantopus} Galapagos Is

Pete Oxford / Giant tortoise {Geochelone elephantopus} Galapagos Islands, Ecuador Charles Darwin Research Stn

Adam White / Giant tortoise {Geochelone elephantopus} wave breaking on back, Aldabra, Seychelles

Ben Lascelles / Aldabra Giant Tortoise (Geochelone gigantea) head portrait. Mauritius.

Ben Lascelles / Aldabra Giant Tortoise (Geochelone gigantea) head in profile. Mauritius.

Mark Carwardine / Aldabra giant tortoise (Geochelone gigantea) captive, vulnerable, from Aldabra and Seychelles, Bristol Zoo

Christophe Courteau / Leopard tortoise (Geochelone pardalis), Okavango Delta, Botswana

Christophe Courteau / Leopard tortoise (Geochelone pardalis) walking on short grass, Okavango Delta, Botswana

Christophe Courteau / African Lioness (Panthera leo) with a Leopard tortoise (Geochelone pardalis) in her mouth, Botswana

Loic Poidevin / Aldabra giant tortoise (Geochelone gigantea) pair mating, Curieuse Marine National Park, Seychelles, Indian Ocean

Loic Poidevin / Aldabra giant tortoise (Geochelone gigantea) pair mating, Curieuse Marine National Park, Seychelles, Indian Ocean

Tui De Roy / Iguna cove giant tortoise (Geochelone vicina), Cerro Azul Volcano, Isabela Island, Galapagos Islands, Ecuador

Tui De Roy / Iguna cove giant tortoise (Geochelone vicina) head, Cerro Azul Volcano, Isabela Island, Galapagos Islands, Ecuador

Michael D. Kern / Red footed tortoise (Geochelone / Chelonoidis carbonaria) captive from South America, vulnerable species.

Michael D. Kern / Red footed tortoise (Geochelone / Chelonoidis carbonaria) captive from South America, vulnerable species.

Michael D. Kern / Red footed tortoise (Geochelone / Chelonoidis carbonaria) mating pair, captive from South America, vulnerable species.

Pete Oxford / Yellow-footed Tortoise (Geochelone denticulata) in rainforest, Yasuni National Park, Amazon Rainforest, Ecuador

Roy Mangersnes / Leopard tortoise (Geochelone pardalis), Okavango Delta, Botswana, November

Roy Mangersnes / Leopard tortoise (Geochelone pardalis), Okavango Delta, Botswana, November

Roy Mangersnes / Leopard tortoise (Geochelone pardalis), Okavango Delta, Botswana, November

Luiz Claudio Marigo / Yellow footed tortoise / Brazilian giant tortoise(Geochelone denticulata) on forest floor, Tableland Atlantic Rainforest of Vale Natural Reserve, municipality of Linhares, Esparito Santo State, Easter...

Luiz Claudio Marigo / Red-footed tortoise (Geochelone carbonaria) on forest floor, Tableland Atlantic Rainforest of Vale Natural Reserve, municipality of Linhares, Esparito Santo State, Eastern Brazil.

Konrad Wothe / Red footed tortoise (Geochelone carbonaria) captive

Pete Oxford / Yellow-footed Tortoise (Geochelone denticulata), Yasuni National Park, Amazon, Ecuador

Roland Seitre / Close up of the posterior spur on the shell of an African spurred tortoise (Centrochelys / Geochelone sulcata) Sahel desert, Ferlo North Reserve, Senegal, West Africa, Vulnerable species.

Roland Seitre / Newly hatched baby African spurred tortoises (Centrochelys / Geochelone sulcata) emerging from burrow, Sahel desert, Ferlo North Reserve, Senegal, West Africa, Vulnerable species. First field study on...

Roland Seitre / African spurred tortoise (Centrochelys / Geochelone sulcata) Sahel desert, Ferlo North Reserve, Senegal, West Africa, Vulnerable species. Two newly hatched babies and one adult over 100 years old, Fir...

Roland Seitre / Newly hatched baby African spurred tortoise (Centrochelys / Geochelone sulcata) held in the hand of a research scientist, Sahel desert, Ferlo North Reserve, Senegal, West Africa, Vulnerable species. F...

Roland Seitre / Egg of an African spurred tortoise (Centrochelys / Geochelone sulcata) held in the hand of a research scientist, Sahel desert, Ferlo North Reserve, Senegal, West Africa, Vulnerable species. First fiel...

Roland Seitre / Antoine Cadi, scientist, and assistants measure the ventral shell of an African spurred tortoise (Centrochelys / Geochelone sulcata) Sahel desert, Ferlo North Reserve, Senegal, West Africa, Vulnerable...

Roland Seitre / African spurred tortoise (Centrochelys / Geochelone sulcata) Sahel desert, Ferlo North Reserve, Senegal, West Africa, Vulnerable species.

Roland Seitre / Antoine Cadi, scientist, and others radio tracking a tagged African spurred tortoise (Centrochelys / Geochelone sulcata) Sahel desert, Ferlo North Reserve, Senegal, West Africa, Vulnerable species. Fi...

Roland Seitre / Antoine Cadi, scientist, checks the ground surrounding the burrow of an African spurred tortoise (Centrochelys / Geochelone sulcata) Sahel desert, Ferlo North Reserve, Senegal, West Africa, Vulnerable...

Roland Seitre / Antoine Cadi, scientist, and others check the ground surrounding the burrow of an African spurred tortoise (Centrochelys / Geochelone sulcata) Sahel desert, Ferlo North Reserve, Senegal, West Africa,...

Roland Seitre / Antoine Cadi, scientist, checks the burrow of an African spurred tortoise (Centrochelys / Geochelone sulcata) Sahel desert, Ferlo North Reserve, Senegal, West Africa, Vulnerable species. First field s...

Roland Seitre / Andrea Gomis, director of the reserve, and Antoine Cadi, scientist, carry an African spurred tortoise (Centrochelys / Geochelone sulcata) Sahel desert, Ferlo North Reserve, Senegal, West Africa, Vulne...

Roland Seitre / Antoine Cadi, scientist, and Andrea Gomis, director of the reserve, study an African spurred tortoise (Centrochelys / Geochelone sulcata) Sahel desert, Ferlo North Reserve, Senegal, West Africa, Vulne...

Roland Seitre / African spurred tortoise (Centrochelys / Geochelone sulcata) Sahel desert, Ferlo North Reserve, Senegal, West Africa, Vulnerable species

Konrad Wothe / Radiated Tortoise (Geochelone radiata) male smelling female in courting ritual, Madagascar

Konrad Wothe / Leopard Tortoise (Geochelone pardalis) grazing, Africa

Konrad Wothe / Red-footed Tortoise (Geochelone carbonaria), South America

John Abbott / Galapagos giant tortoise (Chelonoidis nigra porteri) feeding, Mariposa Ranch on Santa Cruz Island, Galapagos

Ole Jorgen Liodden / Galapagos Giant Tortoise (Chelonoidis nigra). Galapagos

Ole Jorgen Liodden / Leopard Tortoise (Geochelone pardalis). Okavango, Botswana, November.

Pete Oxford / Saddleback form of Galapagos Giant Tortoise (Chelonoidis nigra) Wolf Volcano, Isabela Island, Galapagos

Pete Oxford / Baby Galapagos Giant Tortoise (Chelonoidis nigra) in habitat, Wolf Volcano, Isabela Island, Galapagos

Pete Oxford / Egg of Galapagos Giant Tortoise (Chelonoidis nigra) Wolf Volcano, Isabela Island, Galapagos

Pete Oxford / Egg of Galapagos Giant Tortoise (Chelonoidis nigra) Wolf Volcano, Isabela Island, Galapagos

Pete Oxford / Intermediate form of Galapagos Giant Tortoise (Chelonoidis nigra) Wolf Volcano, Isabela Island, Galapagos

Pete Oxford / Intermediate form of Galapagos Giant Tortoise (Chelonoidis nigra) Wolf Volcano, Isabela Island, Galapagos

Pete Oxford / Faecal pellet of Galapagos Giant Tortoise (Chelonoidis nigra) Wolf Volcano, Isabela Island, Galapagos

Pete Oxford / Saddleback form of Galapagos Giant Tortoise (Chelonoidis nigra) Wolf Volcano, Isabela Island, Galapagos

Pete Oxford / Intermediate form of Galapagos Giant Tortoise (Chelonoidis nigra) Wolf Volcano, Isabela Island, Galapagos

Pete Oxford / Saddleback form of Galapagos Giant Tortoise (Chelonoidis nigra) Wolf Volcano, Isabela Island, Galapagos

Pete Oxford / Saddleback form of Galapagos Giant Tortoise (Chelonoidis nigra) Wolf Volcano, Isabela Island, Galapagos

Pete Oxford / Taking blood from Galapagos Giant Tortoise (Chelonoidis nigra) Charles Darwin Research Station. Puerto Ayora, Santa Cruz, Galapagos

Pete Oxford / Galapagos Giant Tortoise (Chelonoidis nigra porteri) and cattle, Highlands, Santa Cruz Island, Galapagos, September

Lisa Hoffner / Leopard tortoise (Geochelone pardalis) seeks the only shade it can find, its shell, in the heat of the day on the dry riverbed of the Ewaso Nyiro. Kenya. The worst drought (2008-2009) in more than a...