Andy Rouse / Alcedo volcano Galapagos giant tortoise (Chelonoidis vandenburghi) adult male on forest track, Urbina Bay, Isabela Island, Galapagos.

Ann & Steve Toon / Leopard / mountain tortoise (Stigmochelys pardalis) with elephant bull (Loxodonta africana) behind in water, Addo elephant national park, Eastern Cape, South Africa, September

Tui De Roy / Floreana giant tortoise hybrid descendants (Chelonoidis elephantopus) feeding on flower. These are descendants of the extinct Floreana giant tortoise, but are hybridised with other species. Fausto Lle...

Tui De Roy / Alcedo giant tortoise (Chelonoidis vandenburghi) silhouetted at sunrise, Alcedo Volcano, Isabela Island, Galapagos

Tui De Roy / Alcedo giant tortoise (Chelonoidis vandenburghi) group resting in pool, Alcedo Volcano, Isabela Island, Galapagos

Tui De Roy / Alcedo giant tortoise (Chelonoidis vandenburghi) group resting in water at night, Alcedo Volcano, Isabela Island, Galapagos

Tui De Roy / Alcedo giant tortoises (Chelonoidis vandenburghi) group resting in water on moonlit night to keep cool, Alcedo Volcano, Isabela Island, Galapagos

Tui De Roy / Alcedo giant tortoise (Chelonoidis vandenburghi) walking, Alcedo Volcano, Isabela Island, Galapagos

Tui De Roy / Alcedo giant tortoise (Chelonoidis vandenburghi) pair mating in shallow pool, with two others resting nearby. Alcedo Volcano, Isabela Island, Galapagos

Tui De Roy / Western Santa Cruz giant tortoises (Chelonoidis porteri) resting in water, South coast (Las Palmitas), Santa Cruz Island, Galapagos

Tui De Roy / Western Santa Cruz giant tortoise (Chelonoidis porteri) feeding on grass, El Chato II, Highlands, Santa Cruz Island, Galapagos

Tui De Roy / Western Santa Cruz giant tortoise (Chelonoidis porteri) portrait, Highlands, Santa Cruz Island, Galapagos

Chien Lee / Asian Brown Tortoise (Manouria emys) male in rainforest, Tawau Hills Park, Sabah, Malaysia

Tui De Roy / Saddleback Galapagos Tortoise (Chelonoidis nigra hoodensis) in defensive posture, Espanola Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) pair mating, Alcedo Volcano, Isabela Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) on ridge, Alcedo Volcano, Isabela Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi), Alcedo Volcano, Isabela Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi), Alcedo Volcano, Isabela Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) group wallowing in mud at night, Alcedo Volcano, Isabela Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi), Alcedo Volcano, Isabela Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) pair in volcanic landscape, Alcedo Volcano, Isabela Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) group wallowing in mud at night, Alcedo Volcano, Isabela Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) group wallowing in seasonal pond, Alcedo Volcano, Isabela Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) group in volcanic landscape, Alcedo Volcano, Isabela Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) group wallowing in seasonal pond, Alcedo Volcano, Isabela Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) group wallowing in seasonal pond, Alcedo Volcano, Isabela Island, Galapagos Islands, Ecuador

Tui De Roy / Chatham Island Tortoise (Chelonoidis nigra chathamensis), Galapaguera, San Cristobal Island, Galapagos Islands, Ecuador

Ann & Steve Toon / Honey badger (Mellivora capensis) feeding on a Leopard tortoise (Stigmochelys pardalis), Kgalagadi Transfrontier Park, Northern Cape, South Africa.

Pete Oxford / Galapagos Giant Tortoise (Chelonoidis nigra), Santa Cruz Island, Galapagos Islands, Ecuador

Pete Oxford / Galapagos Giant Tortoise (Chelonoidis nigra) grazing, Santa Cruz Island, Galapagos Islands, Ecuador

Tui De Roy / Santa Cruz Galapagos tortoise (Chelonoidis nigra porteri) feeding on grass, Santa Cruz Highlands, Galapagos

Tui De Roy / Santa Cruz Galapagos tortoise (Chelonoidis nigra porteri) feeding on grass, Santa Cruz Highlands, Galapagos

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi), Alcedo Volcano, Isabela Island, Ecuador

Tui De Roy / Hood island giant tortoise (Chelonoidis nigra hoodensis) used for breeding program since 1960s, Tortoise Breeding Centre, Puerto Ayora, Santa Cruz Island, Galapagos Islands, Ecuador, Critically endang...

Tui De Roy / Volcan Alcedo giant tortoises (Chelonoidis nigra vandenburghi) wallowing in rain pools on caldera floor, possibly for thermoregulation or detering parasites, with sulphur fumaroles in background, Alce...

Tui De Roy / Wolf Volcano giant tortoise (Chelonoidis nigra becki) portrait, Isabela Island, Galapagos

Tui De Roy / Wolf-Volcano giant tortoise (Chelonoidis nigra becki) portrait with ground finch (Geospiza sp. ) sitting on foot, Isabela Island, Galapagos. Did you know? Galapagos tortoises have a mutualistic relati...

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

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

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

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

Suzi Eszterhas / African Lion (Panthera leo) mother growling at curious 4 month old cub playing with tortoise, vulnerable, Masai Mara National Reserve, Kenya, sequence 3 of 4

Suzi Eszterhas / African Lion (Panthera leo) curious four month old cub, playing with tortoise, vulnerable, Masai Mara National Reserve, Kenya, sequence 2 of 4

Norbert Wu / Desert Tortoise (Gopherus agassizii), Nevada

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

Larry Minden / Desert Tortoise (Gopherus agassizii) emerging from burrow beneath Mohave Desertrue (Thamnosma montana), Mojave Desert, California

Larry Minden / Desert Tortoise (Gopherus agassizii) in a field of yellow flowers, Mojave Desert, California

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 / Feral Goat (Capra hircus) herd, new invasion causing rapid desertification of last Giant Galapagos Tortoise stronghold, 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

Morley Read / Twistneck turtle (Platemys platycephala) resting, with butterfly landing on its head, Rio Yasuni, Orellana Province, Ecuador. (non-ex)

Ann & Steve Toon / Leopard / Mountain tortoise (Stigmochelys pardalis) small male courting large female, Kgalagadi transfrontier park, South Africa, February

Robert Valentic / Eastern Hermann's tortoise (Eurotestudo hermanni boettgeri), sub-adult on rock. Makri, Alexandroupoli, Evros, East Macedonia and Thrace, Greece.

Tui De Roy / Alcedo giant tortoise (Chelonoidis vandenburghi), group bathing. Alcedo Volcano, Isabella Island, Galapagos. 2017.

Tui De Roy / Alcedo giant tortoise (Chelonoidis vandenburghi) in water at night, star trails in sky reflected in water. Alcedo Volcano, Isabela Island, Galapagos.

Tui De Roy / Alcedo giant tortoise (Chelonoidis vandenburghi) group resting in evening. Steam venting from fumarole in background, Alcedo Volcano, Isabela Island, Galapagos. 2017.

Tui De Roy / Alcedo giant tortoise (Chelonoidis vandenburghi) group sleeping at Alcedo Volcano at night, under starlit sky. Isabela Island, Galapagos.

Tui De Roy / Alcedo giant tortoise (Chelonoidis vandenburghi), group bathing in water at night, with fumarole behind. Alcedo Volcano, Isabella Island, Galapagos.

Fabio Pupin / Angulate tortoise, (Chersina angulata), South Africa, February . Non-ex.

Ralph Pace / Florida Gopher Tortoise (Gopherus polyphemus), Disney Wilderness Preserve, Florida

Andy Rouse / Alcedo volcano Galapagos giant tortoise (Chelonoidis vandenburghi) adult male on forest track, Urbina Bay, Isabela Island, Galapagos.

Andy Rouse / Alcedo volcano Galapagos giant tortoise (Chelonoidis vandenburghi) adult male on forest track, Urbina Bay, Isabela Island, Galapagos.

Andy Rouse / Alcedo volcano Galapagos giant tortoise (Chelonoidis vandenburghi) adult male on forest track, Urbina Bay, Isabela Island, Galapagos.

Andy Rouse / Alcedo volcano Galapagos giant tortoise (Chelonoidis vandenburghi) adult male on forest track, Urbina Bay, Isabela Island, Galapagos.

David Pattyn / Hermann's Tortoise (Testudo Hermanni) in its landscape, Kresna Gorge, South West Bulgaria, April

Martin van Lokven / Ground Hornbill (Bucorvus leadbeateri) predating young Leopard Tortoise (Geochelone pardalis), Ngorongoro Conservation Area, Tanzania

Lorraine Bennery / Radiated tortoise (Astrochelys radiata), walking in dry forest habitat. Tsimanampetsotsa National Park, Madagascar, Critically Endangered.

Nick Hawkins / Volcan Alcedo Galapagos giant tortoise (Chelonoidis nigra vandenburghi), portrait. Isabela Island, Galapagos.

Nick Hawkins / Volcan Alcedo Galapagos giant tortoise (Chelonoidis nigra vandenburghi), portrait. Isabela Island, Galapagos.

Nick Hawkins / Volcan Alcedo Galapagos giant tortoise (Chelonoidis nigra vandenburghi) with neck stretched out. Isabela Island, Galapagos.

David Perpinan / Oesophagostomy tube placed in a captive Red-footed tortoise (Chelonoidis carbonaria). These tubes are placed for animals that refuse eating by themselves. Small repro only.

David Perpinan / Deformed Hermann's tortoise (Testudo hermanni). This is a common condition in Mediterranean tortoises kept in cold weathers or under inadequate husbandry. Small repro only

David Perpinan / Radiography of a Spider tortoise (Pyxis arachnoides) showing a characteristic of this species - they just lay one egg. Captive. Small repro only.

David Perpinan / Microscopic image of oxyurid nematode parasites in the faecal sample of a captive Hermann's tortoise (Testudo hermanni) Small repro only.

David Perpinan / Sexual differences between female (left) and male (right) adult Egyptian tortoises (Testudo kleinmanni). dorsal view. Captive animals. small repro only

David Perpinan / Sexual dimorphism in adult red-footed tortoise (Chelonoidis carbonaria). Left: male (concave plastron, long tail), right: female (flat plastron, short tail) small repro only

David Perpinan / Female (left) and male (right) adult Egyptian tortoises (Testudo kleinmanni). Sexual dimorphism. Captive (exotic pet trade). Spain. Ventral view. small repro only

David Perpinan / Hatching of an egg from an African spurred tortoise (Geochelone sulcata) after artificial incubation. Captive small repro only

David Perpinan / Carapacial fracture in a gopher tortoise (Gopherus polyphemus) after being hit by a car. Rehabilitation Centre, Georgia, United States. Small repro only

Sean Crane / Red-footed Tortoise (Geochelone carbonaria), Saint Barts, Caribbean