Mark Taylor / German Shepherd Dog bitch pup, Coco, 14 weeks old, with raised paw.

Piotr Naskrecki / Millipede close up showing body segments and legs, Mamang River Forest Reserve, Ghana

Albert Lleal / SEM close-up of a millipede at 70x magnification showing 2 pair of legs per body section, the attribute distinguishing this group from centipedes which have but a single pair of legs per section

Albert Lleal / SEM close-up of a millipede at 70x magnification showing 2 pair of legs per body section, the attribute distinguishing this group from centipedes which have but a single pair of legs per section

Piotr Naskrecki / Malagasy Web-footed Frog (Boophis luteus) clinging to limb, Madagascar

Michael & Patricia Fogden / Tiger-striped Leaf Frog (Phyllomedusa tomopterna) on Heliconia (Heliconia stricta), Amazon rainforest, Peru

Yva Momatiuk & John Eastcott / Black-bellied Plover (Pluvialis squatarola) non-breeding bird resting on one leg on shore, spring, Gulf of Mexico, Padre Island National Seashore, Texas

Claus Meyer / Tiger-striped Leaf Frog (Phyllomedusa tomopterna) waving, Amazon rainforest, Brazil

Gerry Ellis / Lesser Panda (Ailurus fulgens) sitting on tree limb, China, Nepal, Burma

Tui De Roy / Scarlet Macaw (Ara macao) pair perched on tree limb, originally hand raised by the research center, they are now living in the rainforest canopy, Tambopata-Candamo Reserve, Amazon Basin, Peru

Flip Nicklin / Sea Star, Anemones and Coralline Algae living 40 feet below the water surface, Admiralty Inlet, Lancaster Sound, Nunavut, Canada

ZSSD / African Elephant (Loxodonta africana) calf leaning on its mothers legs, native to Africa

Dave Watts / Platypus swimming underwater {Ornithorhynchus anatinus} Australia. Digital composite.

Suzi Eszterhas / Hoffmann's Two-toed Sloth (Choloepus hoffmanni) orphan baby clinging to person's arms, Aviarios Sloth Sanctuary, Costa Rica

David Welling / Great kiskadee (Pitangus sulphuratus) perches on a dead mesquite tree limb, with food in beak, Laguna Seca Ranch near Edinburgh, Texas, United States

Anup Shah / Western chimpanzee (Pan troglodytes verus) infant male 'Flanle' aged 3 years spinning in circles, Bossou Forest, Mont Nimba, Guinea. January 2011.

Donald M. Jones / Wild Turkey (Meleagris gallopavo) leg showing spur used in fighting, Troy, Montana

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) limb and claws. Galapagos Islands, Ecuador, May.

Martin Willis / Eastern Grey Kangaroo (Macropus giganteus) licking arms to stay cool, Tasmania, Australia

Chris Newbert / Blue Sea Star (Linckia laevigata) with two new arms budding from one leg, Indonesia

Ben Lascelles / Yacare Caiman (Caiman yacare) skin and limb-joint close up. Ibera wetlands, Corrientes, Argentina, October.

Donald M. Jones / Common Loon (Gavia immer) stretching leg, Troy, Montana

Piotr Naskrecki / Katydid (Mossula sp), newly discovered species, kicking legs to protect itself, Papua New Guinea

Piotr Naskrecki / Jumping Spider (Diolenius sp) with greatly enlarged front legs, Papua New Guinea

Piotr Naskrecki / Katydid (Phyllophora sp) leg with ridges used to produce hissing sound when rubbed against the sternum, Papua New Guinea

Tony Phelps / Bite from Cape Cobra snake (Naja nivea) on human limb,48 hours after the bite, showng blistering and swelling. Western Cape, South Africa. Model released

David Welling / Black-billed Cuckoo (Coccyxus erythropthalmus) perching on a tree limb. South Padre Island, Cameron County, texas, USA, April.

Thomas Marent / Harlequin Flying Tree Frog (Rhacophorus pardalis) hind limb with webbing, Forest Research Institute Malaysia, Malaysia

Thomas Marent / Palmate Newt (Triturus helveticus) eating Common Frog (Rana temporaria) tadpole, Switzerland

Pete Oxford / Fish dried by Macushi people, Yupukari Village, Rupununi, Guyana

Mary McDonald / Keel-billed Toucan (Ramphastos sulfuratus) adult in full breeding plumage on a tree limb at the edge of the lowland rainforest. Laguana del Lagarto, Costa Rica, Central America.

Mary McDonald / Keel-billed Toucan (Ramphastos sulfuratus) adult in full breeding plumage on a tree limb at the edge of the lowland rainforest. Laguana del Lagarto, Costa Rica, Central America.

Mary McDonald / Green-crowned Brillant (Heliodoxa jacula) male perched on tree limb, Bosque de Paz, Costa Rica, Central America.

Edwin Giesbers / Two Kodiak / Alaskan brown bears (Ursus arctos middendorffi) head portrait in water, with paw resting against tree limb, captive.

James Christensen / Equatorial Anole (Anolis aequatorialis) young male perched on mossy tree limb, Mindo, Ecuador

James Christensen / Equatorial Anole (Anolis aequatorialis) on mossy tree limb, Mindo, Ecuador

Suzi Eszterhas / Sumatran Orangutan (Pongo abelii) arm, Gunung Leuser National Park, north Sumatra, Indonesia

ZSSD / Western Lowland Gorilla (Gorilla gorilla gorilla) young holding onto leg of zoo staff member, native to Africa

Pete Oxford / Marsupial Frog (Gastrotheca riobambae) tadpole hind legs, Andes, Ecuador

Chien Lee / Katydid (Tettigoniidae) raising its legs in a defensive posture, Mount Kinabalu National Park, Borneo, Malaysia

Richard Du Toit / Reticulated Giraffe (Giraffa reticulata) tail and legs, Ol Pejeta Conservancy, Kenya

Albert Lleal / Mediterranean Mantis (Iris oratoria) detail of spines on front legs at 14x magnification, Spain

Albert Lleal / Painted Lady (Vanessa cardui) leg, Spain

Donald M. Jones / Wild Turkey (Meleagris gallopavo) male's foot and spur, western Montana

Steven David Miller / King parrot (Alisterus scapularis) male perched in tree limb listening to other birds calling, captive, Adelaide Zoo, South Australia

Norbert Wu / Bat Star (Asterina miniata) with regenerated arm, Monterey, California

Norbert Wu / Bat Star (Asterina miniata) with regenerated arm, Monterey, California

Piotr Naskrecki / Millipede showing body segments and legs, Atewa Range, Ghana

Piotr Naskrecki / Katydid (Arantia sp) cleaning leg, Mamang River Forest Reserve, Ghana

Piotr Naskrecki / Millipede climbing, Atewa Range Forest Reserve, Ghana

Piotr Naskrecki / Millipede body and legs, Atewa Range Forest Reserve, Ghana

Piotr Naskrecki / Millipede body and legs, Atewa Range Forest Reserve, Ghana

Pete Oxford / Waved Albatross (Phoebastria irrorata) foot with band, Hood Island, Galapagos Islands, Ecuador

Yva Momatiuk & John Eastcott / Mustang (Equus caballus) leg with primitive striped markings, Pryor Mountain National Wild Horse Range, Montana

Thomas Marent / Millipede legs, Montagne des Francais Reserve, Antsiranana, northern Madagascar

Thomas Marent / Tiger's Treefrog (Hyloscirtus tigrinus) back leg, new species discovered in 2007, Colombia

Norbert Wu / Sea Star (Solaster sp) regenerating arms, Vancouver Island, Canada

Norbert Wu / Sunflower Sea Star (Pycnopodia helianthoides) arms curling around a blade of kelp, Alaska

Yva Momatiuk & John Eastcott / Southern Elephant Seal (Mirounga leonina) bull hind flippers, St. Andrews Bay, South Georgia Island

Winfried Wisniewski / White Rhinoceros (Ceratotherium simum) leg folded under, Lake Nakuru National Park, Kenya

Norbert Wu / Common Basket Star (Gorgonocephalus eucnemis) with branching arms which are only seen at night in warmer waters, Alaska

Albert Lleal / Grasshopper (Anacridium sp) SEM close-up view of leg showing spikes at 35x magnification

Albert Lleal / Human Louse (Pediculus humanus) SEM close-up view of prehensile leg and human hair at 210x magnification

Heidi & Hans-Juergen Koch / Honey Bee (Apis mellifera) with pollen baskets on hind legs, Bee Station at the Bavarian Julius-Maximilians-University of Wurzburg, Germany

Suzi Eszterhas / Black-backed Jackal (Canis mesomelas) carrying gazelle leg, Masai Mara, Kenya

Pete Oxford / White-fronted Capuchin (Cebus albifrons) checking pant pocket of person, Puerto Misahualli, Amazon Rainforest, Ecuador

Pete Oxford / White-fronted Capuchin (Cebus albifrons) checking pant pocket of person, Puerto Misahualli, Amazon Rainforest, Ecuador

Sergey Gorshkov / Brown Bear (Ursus arctos) feet holding caught salmon, Kamchatka, Russia

Heidi & Hans-Juergen Koch / Honey Bee (Apis mellifera) with pollen baskets, Bee Station at the Bavarian Julius-Maximilians-University of Wurzburg, Germany

Thomas Marent / Tarantula (Theraphosidae) leg, showing fine hairs used as sense organs, Tambopata-Candamo Nature Reserve, Peru

Thomas Marent / Lubber Grasshopper (Tropidacris sp) leg, showing spines used as defense, Peru

Christian Ziegler / Foam-nest Frog (Leptodactylus sp) feeding on a Red-eyed Tree Frog (Agalychnis callidryas) at a mating pond, Soberania National Park, Panama

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

Peter Scoones / Red handfish {Brachyionichthys politus} Tasmania, Australia

Tim Fitzharris / Raccoon (Procyon Lotor) baby climbing on dead tree limb, North America

Chris Newbert / Cortez Starfish (Pentaceraster cumingi) arm with Shrimp, 80 feet deep, Papua New Guinea

Shin Yoshino / Saddle-billed Stork (Ephippiorhynchus senegalensis) standing in wetland, Savute, Botswana

Richard Du Toit / Bushveld Elephant Shrew (Elephantulus intufi) scratching itself, Kgalagadi Transfrontier Park, South Africa

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 / Giant Helmeted Katydid (Phyllophorella woodfordi) climbing on limb with brown ear membranes visible on forelegs, Solomon Islands

Piotr Naskrecki / Old World Tree Frog (Chiromantis sp) camouflaged on limb, Guinea, West Africa

Mark Raycroft / Australian Kelpie (Canis familiaris) standing on hind legs

Jane Burton / Common Frog (Rana temporaria) tadpole with fully developed limbs, the forelegs ready to burst out of opercula (one toe of the right limb is already out)

Pete Oxford / Katydid (Steirodon sp) close-up showing ear on front leg, western slopes of the Andes, Ecuador

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

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

Pete Oxford / Marsupial Frog (Gastrotheca riobambae) first day out of water, Ecuador

Gerry Ellis / Greater Flamingo (Phoenicopterus ruber) parent on nest with egg, Inagua National Park, Bahamas

Gerry Ellis / Rain Spider (Palystes sp) close-up, Ndumo Game Reserve, South Africa

Tom Vezo / Common Snipe (Gallinago gallinago) resting on one leg on snow-covered post, Teton Valley, Idaho

Heidi & Hans-Juergen Koch / Domestic Dog (Canis familiaris) sitting on the beach, scratching with hind leg, Armacao De Pera Algarve, Portugal

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

Ingo Arndt / Harlequin Beetle (Acrocinus longimanus) underside detail of leg and foot

Ingo Arndt / Harlequin Beetle (Acrocinus longimanus) underside detail of leg and foot

Pete Oxford / White-lined Leaf Frog (Phyllomedusa vaillanti) tadpole, first day out of water, Amazon, Ecuador

Pete Oxford / White-lined Leaf Frog (Phyllomedusa vaillanti) tadpole tail almost completely absorbed into the body, Amazon, Ecuador