Jouan & Rius / Blue headed ground agama (Agama aculeata) standing up on hind legs, Kgalagadi Transfrontier Park, Kalahari desert, South Africa

Carol Walker / Black Freisian stallion, close up of legs and hoof, Ojai, California, USA, model released

Nick Turner / Close-up of walker's legs and walking boots at Llyn y Fan Fach, Brecon Beacons National Park, Powys, Wales

Ingo Arndt / Daddy Long-legs close up, Germany

Anup Shah / Close up of legs and tail of Giraffe {Giraffa camelopardalis} backlit at sunrise, East Africa

Premaphotos / Grasshopper (Agriacris trilineata), close up of spines on back leg which are used in defense, Peru

ZSSD / Orange-spotted Millipede (Anadenobolus arboreus gundlachi) detail of body segments and legs, native to Puerto Rico

PREMAPHOTOS / Close up of feet of caterpillar larva of Noctuid moth (Apopestes spectrum) with its prolegs grasping a leaf stem, Israel

Jane Burton / English Springer Spaniel dog sitting up on his hind legs

Jane Burton / Patterdale x Jack Russell Terrier standing on hind legs looking up at treat held by owner.

Jane Burton / Ruby Cavalier King Charles Spaniel bitch, standing up on hind legs

Jane Burton / Sable Border Collie standing up on hind legs

Jose B. Ruiz / Common crane {Grus grus} close-up of feet on ice, Laguna de Gallocanta, Teruel, Aragón, Spain

Jose B. Ruiz / Common crane {Grus grus} close-up of feet, Laguna de Gallocanta, Teruel, Aragón, Spain

Michael D. Kern / Aldabra tortoise {Geochelone gigantea} close-up profile of head and legs, captive, Aldabra Islands

Nature Production / Close up of hind leg of Migratory Locust {Locusta migratoria} Japan

Jane Burton / Cocker Spaniel standing on hind legs and bouncing up.

Petra Wegner / Domestic dog, Miniature Schnauzer (black-silver), standing on hind legs looking up

Piotr Naskrecki / Gladiator Heelwalker (Tyrannophasma gladiator) ferocious nocturnal predator that uses both front and middle legs to grab and crush its spider and insect prey, Namibia

Piotr Naskrecki / Mantid (Tauromantis championi) mating, male positions himself as far from female's front legs as possible to increase chances of survival

Piotr Naskrecki / Spider (Ricinoides afzelii) the second pair of legs of males is enlarged and probably used in combat with other members of its species, Guinea, West Africa

Piotr Naskrecki / Harvestman (Opiliones) portrait on moss, Costa Rica

Piotr Naskrecki / Daddy-Long-Legs Spider (Pholcus phalangioides) devouring an arboreal Earthworm, Costa Rica

Piotr Naskrecki / Daddy-Long-Legs Spider (Pholcus phalangioides) the body resembles a gondola suspended on long flexible stilts, Guinea, West Africa

Piotr Naskrecki / Daddy-Long-Legs Spider (Pholcus phalangioides) close-up, Costa Rica

Piotr Naskrecki / Daddy-Long-Legs Spider (Pholcus phalangioides) some are brightly colored, possibly to advertise their distastefulness, Guinea, West Africa

Piotr Naskrecki / Cochran's Running Frog (Kassina cochranae) rarely jumps, it instead prefers to run swiftly on its beautifully spotted legs, Guinea, West Africa

Andy Sands / Hornet Robberfly (Asilus crabroniformis) portrait. Close up of head, Buckinghamshire, UK

Pete Cairns / European Lynx (Lynx lynx) close up of front legs of adult female. Bardu, Norway, captive

Jabruson / Hippopotamus {Hippopotamus amphibius} close up of leg caught in snare, Rwindi, Virunga NP, Dem Rep Congo

Nigel Bean / Close up of legs of Grevy zebra {Equus grevyi} captive

Michael Hutchinson / Close up of legs and webbed feet of Herring Gull {Larus argentatus} California, USA

Philippe Clement / Close up of legs of Mexican red-knee tarantula {Brachypelma smithi} captive, central america

Jane Burton / Domestic Cat {Felis catus} lilac-and-white Burmese-cross kitten standing on rear legs among Pink chrysanthemums and Heather

Jane Burton / Domestic Cat {Felis catus} 10-week Black smoke British shorthair kitten, sitting up on back legs

Jane Burton / Domestic cat (Felis catus) 9-week-old kitten playing, sitting up on back legs

Jane Burton / Domestic cat (Felis catus) 12-week-old kitten playing, sitting up on back legs

Jane Burton / Domestic cat (Felis catus) 9-week-old kitten playing sitting up on back legs

Staffan Widstrand / Close-up of horses {Equus caballus} hoof, Sweden.

Eric Baccega / Close up of Korowai feet, Western Papuasia, Indonesia. 1999 / 2000. (West Papua).

Pete Oxford / Marsupial froglet climbing up leaf {Gastrotheca sp} Ecuador

Pete Oxford / Marsupial froglet climbing up leaf {Gastrotheca sp} Ecuador

Brent Hedges / Red hermit crab {Dardanus megistos} close-up, Solomon Islands, South Pacific

Steven David Miller / Close up of skin and leg of American alligator {Alligator mississippiensis} Florida, USA.

Mark Raycroft / Standard Smooth Dachshund (Canis familiaris) adult with front legs up on a rock on green lawn

Pete Oxford / Marsupial Frog (Gastrotheca riobambae) tadpole with back legs developed, Andes Mountains, Ecuador

Pete Oxford / Marsupial Frog (Gastrotheca riobambae) tadpole underwater, back and front legs developed, Ecuador

Winfried Wisniewski / Cheetah (Acinonyx jubatus) legs of cheetah, Africa

Duncan Usher / Midwife Toad (Alytes obstetricans) adult male carries eggs wrapped around his hind-legs until they hatch, Europe

Richard Du Toit / South African Giraffe (Giraffa giraffa giraffa) legs of several animals standing together, Phinda Game Reserve, South Africa

Mark Moffett / Wind Scorpion (Galeodidae) male at left lunges at a female tearing her body and damaging her legs before mating, desert, Iran

Ingo Arndt / Ball Python (Python regius) evolved from lizards and still has claw-like spurs which are evolutionary remnant of legs on underside

Jose B. Ruiz / Close up of limbs of Red seastar {Echinaster sepositus} Mediterranean

Mark Moffett / Harvestman (Phalangodidae) an arachnid, close-up portrait showing fused abdomen which differentiates Harvestmen from other spiders, Parana State, Atlantic Forest, Brazil

Michael & Patricia Fogden / Flag-footed Bug (Anisocelis flavolineata) pair displaying flagged legs and mating on Passionvine leaf with female feeding, rainforest, Costa Rica

Yva Momatiuk & John Eastcott / Bald Eagle (Haliaeetus leucocephalus) powerful yellow legs and talons get pigment from salmon-rich diet, spring, south central Alaska

Heidi & Hans-Juergen Koch / Cayenne Slender-legged Tree Frog (Osteocephalus leprieurii) silhouette of tadpole with developed tail and legs, native to South America

Heidi & Hans-Juergen Koch / Cayenne Slender-legged Tree Frog (Osteocephalus leprieurii) tadpole with developed tail and legs, native to South America

Mark Moffett / Marauder Ant (Pheidologeton diversus) swarm of minor workers with major worker carry lizard that is still alive, but its legs have been torn off

Claus Meyer / Centipede (Otostigmus sp) showing many legs, southern Brazil

Claus Meyer / Centipede (Otostigmus sp) showing many legs, southern Brazil

Gerry Ellis / Praying Mantis (Mantis sp) head and legs, Los Cedros River Valley, Ecuador

Patricio Robles Gil / Asian Elephant (Elephas maximus) with its trunk between its front legs, Sri Lanka

Norbert Wu / Millipede (Tylobolus deses) has 300 legs, California

Norbert Wu / Millipede (Tylobolus deses) coiled into a protective ball, has 300 legs, California

Mark Moffett / Yellow-kneed Tarantula (Selenocosmia javanensis) interior of shed skin showing holes from legs, Java

Mark Moffett / Marauder Ant (Pheidologeton diversus) swarm attacking photographer Mark Moffett's legs, Malaysia

Gertrud & Helmut Denzau / Himalayan marmot {Marmota bobak himalayana} sitting on hind legs, Ladakh, India

David Shale / Deep sea jellyfish {Periphylla sp} Atlantic ocean

Constantinos Petrinos / Veined / Marginated octopus {Octopus marginatus} climbs into shell for protection and buries it in seabed using its funnel and legs. Shells are found in seabed and dug up and cleaned by octopus. Lembe...

Dave Watts / Female Crested black / Concolor gibbon {Hylobates concolor} standing up on hind legs. Endangered species native to the forests of South China to Vietnam.

Paul D Stewart / Illustrations of Birds of Paradise (Paradisaea spp), woodcut from Merian and Jonston's 'Historia Naturalis' 1660 (which continued to be printed up to 1767). Shows a range of species including the blue...

Nick Upton / Moulted crarapaces and legs of Common spider crabs / Spiny spider crabs (Maja brachydactyla / Maja squinado) and moulted carapaces washed up on Rhossili Bay, with the Worm's Head in the background, Th...

Nick Upton / Moulted carapaces and legs of Common spider crabs / Spiny spider crabs (Maja brachydactyla / Maja squinado) washed up on sandy beach. Rhossili Bay, The Gower Peninsula, UK, July.

Nick Upton / Moulted carapace and legs of Common spider crab / Spiny spider crab (Maja brachydactyla / Maja squinado) washed up on sandy beach. Rhossili Bay, The Gower Peninsula, UK, July.

Konrad Wothe / Oldworld Swallowtail (Papilio machaon) caterpillar legs, Upper Bavaria, Germany

Petra Wegner / Satin Dwarf Rabbit, sitting up on hind legs

Petra Wegner / Lion-maned Dwarf Rabbit, black-and-white, sitting up on hind legs

Petra Wegner / French Bulldog, male standing up on hind legs

Petra Wegner / French Bulldog, male standing up on hind legs

Petra Wegner / French Bulldog, male standing up on hind legs

Petra Wegner / French Bulldog, male standing up on hind legs

Bernard Castelein / Gerenuk (Litocranius walleri) feeding up on hind legs, Samburu NP, Kenya, East Africa

Winfried Wisniewski / Ostrich (Struthio camelus) legs of a non-sexual adult, Africa

SIMON KING / Meerkat up on hind legs {Suricata suricatta} Tswalu Kalahari Reserve South Africa

Ben Osborne / Dolphin gull close-up of legs {Larus scoresbii} Falkland Is