Will Burrard-Lucas / Tufted gray langur (Semnopithecus priam) Close up portrait of head and shoulders. Minneriya National Park, Sri Lanka. September

Chase Dekker / Humpback Whale (Megaptera novaeangliae) pod gulp feeding on Northern Anchovy (Engraulis mordax), Monterey Bay, California

Chase Dekker / African Lion (Panthera leo) male, Masai Mara, Kenya

Gerry Ellis / Chimpanzee (Pan troglodytes) orphans, Larry investigating Daphne's tongue, Ape Action Africa, Mefou Primate Sanctuary, Cameroon

Jami Tarris / Walrus (Odobenus rosmarus) bull, Spitsbergen, Svalbard, Norway

Jami Tarris / Golden Eagle (Aquila chrysaetos) huntress, Altai Mountains, Bayan Ulgii, Mongolia

Juergen & Christine Sohns / African Lion (Panthera leo) male drinking at waterhole, Tswalu Game Reserve, South Africa

Juergen & Christine Sohns / African Wild Dog (Lycaon pictus) group attacking Cape Warthog (Phacochoerus aethiopicus), Tswalu Game Reserve, South Africa

Fiona Rogers / Eastern Chimpanzee (Pan troglodytes schweinfurthii) twenty year old male, named Titan, Gombe National Park, Tanzania

Fiona Rogers / Eastern Chimpanzee (Pan troglodytes schweinfurthii) twenty-five year old female, named Tanga, Gombe National Park, Tanzania

Fiona Rogers / Eastern Chimpanzee (Pan troglodytes schweinfurthii) four year old infant male, named Gizmo, Gombe National Park, Tanzania

Fiona Rogers / Eastern Chimpanzee (Pan troglodytes schweinfurthii) eighteen year old male, named Sampson, Gombe National Park, Tanzania

Fiona Rogers / Eastern Chimpanzee (Pan troglodytes schweinfurthii) four year old infant male, named Gizmo, Gombe National Park, Tanzania

Heike Odermatt / Walrus (Odobenus rosmarus), Hinlopen Strait, Svalbard, Norway

Gary Bell/ Oceanwide / Veined Octopus (Octopus marginatus) hiding in glass jar, Lembeh Strait, Indonesia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning mouth of Tomato Grouper (Cephalopholis sonnerati), Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning mouth of Tomato Grouper (Cephalopholis sonnerati), Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Whitemouth Moray (Gymnothorax meleagris) being cleaned by Cleaner Wrasse (Labroides sp) juvenile, Christmas Island, Australia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning Yellow-edged Moray (Gymnothorax flavimarginatus), Tulamben, Bali, Indonesia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning Honeycomb Moray Eel (Gymnothorax favagineus), Tulamben, Bali, Indonesia

Gary Bell/ Oceanwide / Variegated Jawfish (Opistognathus solorensis) male brooding eggs in mouth, Anilao, Philippines

Gary Bell/ Oceanwide / Variegated Jawfish (Opistognathus solorensis) male brooding eggs in mouth, Anilao, Philippines

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning mouth of Goldbelly Cardinalfish (Apogon apogonides), Tulamben, Bali, Indonesia

Suzi Eszterhas / Leopard (Panthera pardus) six-week-old cub nursing, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) mother playing with her six-week-old cub, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) five-week-old cub, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) five-week-old cub, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) mother grooming five-week-old cub, Jao Reserve, Botswana

Suzi Eszterhas / Leopard (Panthera pardus) five-week-old cub playing with mother, Jao Reserve, Botswana

Marie Read / Great blue heron (Ardea herodias) in breeding plumage, head and shoulders showing plumes on crown and neck, Montezuma National Wildlife Refuge, New York, USA, May.

Willi Rolfes/ BIA / European Wolf (Canis lupus), Lower Saxony, Germany

Willi Rolfes/ BIA / European Wolf (Canis lupus), Lower Saxony, Germany

Willi Rolfes/ BIA / European Wolf (Canis lupus), Lower Saxony, Germany

Willi Rolfes/ BIA / European Wolf (Canis lupus), Lower Saxony, Germany

Willi Rolfes/ BIA / European Wolf (Canis lupus), Lower Saxony, Germany

Marion Vollborn/ BIA / Polar Bear (Ursus maritimus), Svalbard, Norway

Marion Vollborn/ BIA / Polar Bear (Ursus maritimus), Svalbard, Norway

Richard Du Toit / Northern Giraffe (Giraffa camelopardalis) calves, iSimangaliso Wetland Park, KwaZulu-Natal, South Africa

Gary Bell/ Oceanwide / Intermediate Cardinalfish (Cheilodipterus intermedius) male incubating eggs in mouth, Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Intermediate Cardinalfish (Cheilodipterus intermedius) male incubating eggs in mouth, Great Barrier Reef, Australia

Paul Souders/ Worldfoto / African Elephant (Loxodonta africana) calf feeding, Ngorongoro Conservation Area, Tanzania

Donald M. Jones / White-tailed Deer (Odocoileus virginianus) mother cleaning fawn, Montana

Donald M. Jones / Black-tailed Prairie Dog (Cynomys ludovicianus) group, South Dakota

Thomas Marent / Buckley's Slender-legged Treefrog (Osteocephalus buckleyi), Putumayo, Colombia

Paul Souders/ Worldfoto / Humpback Whale (Megaptera novaeangliae) pod cooperative bubble-net feeding, Frederick Sound, Alaska

Chase Dekker / Humpback Whale (Megaptera novaeangliae) gulp feeding on Northern Anchovy (Engraulis mordax), Monterey Bay, California

Chase Dekker / Humpback Whale (Megaptera novaeangliae) pod gulp feeding, Monterey Bay, California

Ingo Arndt / Mountain Lion (Puma concolor), Torres del Paine National Park, Patagonia, Chile

Ingo Arndt / Mountain Lion (Puma concolor), Torres del Paine National Park, Patagonia, Chile

Ingo Arndt / Royal Flycatcher (Onychorhynchus coronatus) in defensive posture, Santa Rosa National Park, Costa Rica

Ingo Arndt / Royal Flycatcher (Onychorhynchus coronatus) in defensive posture, Santa Rosa National Park, Costa Rica

Suzi Eszterhas / African Lion (Panthera leo) young male feeding on Cape Buffalo (Syncerus caffer) prey, Sabi Sands Private Game Reserve, South Africa

Suzi Eszterhas / Komodo Dragon (Varanus komodoensis) pair flicking tongues, Komodo National Park, Indonesia

Marion Vollborn/ BIA / Cheetah (Acinonyx jubatus) cub, Castile-La Mancha, Spain

Anup Shah / Olive Baboon (Papio anubis) curious male investigating camera, Masai Mara, Kenya

Richard Du Toit / Northern Giraffe (Giraffa camelopardalis) with Red-billed Oxpeckers (Buphagus erythrorhynchus) feeding on parasites in symbiotic relationship, Mkhuze Game Reserve, KwaZulu-Natal, South Africa

Richard Du Toit / Impala (Aepyceros melampus) males fighting, Mkhuze Game Reserve, KwaZulu-Natal, South Africa

Piotr Naskrecki / African Lungfish (Protopterus annectens), Gorongosa National Park, Mozambique

Winfried Wisniewski / Hippopotamus (Hippopotamus amphibius) in territorial display, Mkhuze Game Reserve, KwaZulu-Natal, South Africa

Juergen & Christine Sohns / Swamp Wallaby (Wallabia bicolor) mother and joey, Mount Lofty, South Australia, Australia

Shane P. White / Japanese Macaque (Macaca fuscata) in hot spring, Jigokudani, Nagano, Japan

Hiroya Minakuchi / Humpback Whale (Megaptera novaeangliae) trio gulp feeding, Inside Passage, southeast Alaska

Sebastian Kennerknecht / American Bison (Bison bison) female in winter, Yellowstone National Park, Wyoming

Cyril Ruoso / Long-tailed Macaque (Macaca fascicularis) pair grooming, Khao Sam Roi Yot National Park, Thailand

Yva Momatiuk & John Eastcott / Atlantic Puffin (Fratercula arctica), Latrabjarg, Westfjords, Iceland

Mark Raycroft / White-tailed Deer (Odocoileus virginianus) buck in snowfall, North America

Mark Raycroft / Border Collie (Canis familiaris), North America

Suzi Eszterhas / Mallard (Anas platyrhynchos) rehabilitator, Isabel Luevano, with one day old orphan duckling, International Bird Rescue, Fairfield, California

Michael Quinton / Northern Hawk Owl (Surnia ulula) pair at nest, Alaska

Michael Quinton / Northern Hawk Owl (Surnia ulula) peering from nest, Alaska

Hiroya Minakuchi / Humpback Whale (Megaptera novaeangliae) pod gulp feeding, Inside Passage, southeast Alaska

Hiroya Minakuchi / Humpback Whale (Megaptera novaeangliae) pod gulp feeding, Inside Passage, southeast Alaska

Agustin Esmoris / Southern Right Whale (Eubalaena australis) surfacing with Kelp Gull (Larus dominicanus) picking off lice, Chubut, Argentina, sequence 1 of 4

Sebastian Kennerknecht / African Elephant (Loxodonta africana) bulls fighting, Kruger National Park, South Africa

Sebastian Kennerknecht / Leopard (Panthera pardus) female feeding on sub-adult male Impala (Aepyceros melampus) prey in tree, Greater Makalali Private Game Reserve, South Africa

Sebastian Kennerknecht / Harbor Seal (Phoca vitulina) pup, Elkhorn Slough, Monterey Bay, California

Sebastian Kennerknecht / Harbor Seal (Phoca vitulina) pup, Elkhorn Slough, Monterey Bay, California

Sebastian Kennerknecht / American Bison (Bison bison) bull browsing in winter, Yellowstone National Park, Wyoming

Sebastian Kennerknecht / American Bison (Bison bison) female cleaning nose with tongue, Yellowstone National Park, Wyoming

Sebastian Kennerknecht / American Bison (Bison bison) female covered with frost in winter, Yellowstone National Park, Montana

Heike Odermatt / Walrus (Odobenus rosmarus), Svalbard, Norway

Richard Du Toit / Burchell's Zebra (Equus burchellii) trio nuzzling, Itala Game Reserve, South Africa

Cyril Ruoso / Long-tailed Macaque (Macaca fascicularis) group, Khao Sam Roi Yot National Park, Thailand

Cyril Ruoso / Long-tailed Macaque (Macaca fascicularis) using stone tool to break shell, Khao Sam Roi Yot National Park, Thailand

Cyril Ruoso / Chimpanzee (Pan troglodytes) using stick to forage for prey in small tree cavity, Bossou, Guinea

Yva Momatiuk & John Eastcott / Atlantic Puffin (Fratercula arctica) with fish prey, Borgarfjordur Eystri, Iceland

Fiona Rogers / Eastern Chimpanzee (Pan troglodytes schweinfurthii) five year old juvenile female, named Fadhila, playing with her three year old brother, named Fifty, Gombe National Park, Tanzania

Donald M. Jones / Yellow-bellied Marmot (Marmota flaviventris) yawning, central Montana

Donald M. Jones / White-tailed Deer (Odocoileus virginianus) buck, western Montana

Donald M. Jones / Elk (Cervus elaphus) bull bugling, western Canada

Donald M. Jones / Bighorn Sheep (Ovis canadensis) ram, western Montana

Donald M. Jones / American Darter (Anhinga anhinga) preening, Everglades National Park, Florida

Jami Tarris / Japanese Macaque (Macaca fuscata) in hot spring, Jigokudani, Nagano, Japan

Christof Wermter/ BIA / Demoiselle Crane (Anthropoides virgo) parent with chick, Germany

Tim Fitzharris / Sumatran Orangutan (Pongo abelii) male, native to Sumatra

Tui De Roy / Galapagos Lava Lizard (Microlophus albemarlensis) on Marine Iguana (Amblyrhynchus cristatus), Punta Espinosa, Fernandina Island, Galapagos Islands, Ecuador