Florian Möllers / Golden snub-nosed monkey (Rhinopithecus roxellana qinlingensis) adult male yawning showing canine teeth, Zhouzi Nature Reserve, Qinling mountains, Shaanxi, China. April 2006

Anup Shah / Bornean Orangutan (Pongo pygmaeus wurmbii) sub-adult male 'Pan' yawning - head portrait. Camp Leakey, Tanjung Puting National Park, Central Kalimantan, Borneo, Indonesia. June 2010. Rehabilitated and...

Anup Shah / Nile crocodile (Crocodylus niloticus) emerging from the Mara River - wide angle perspective, Masai Mara National Reserve, Kenya. August 2009.

Edwin Giesbers / Konik Wild Horse (Equus ferus caballus) yawning. The Netherlands, November.

Edwin Giesbers / Two Konik Wild Horse (Equus ferus caballus) interacting. The Netherlands, November.

Sergey Gorshkov / Kamchatka Brown bear (Ursus arctos beringianus) catching salmon in river, Kamchatka, Far east Russia, August

Fergus Gill / Greylag goose (Anser anser) calling at dawn with its breath showing as a cloud of steam. Serrated tomia (the equivalent of teeth) are visible in its beak. Scotland, Dec .

Orsolya Haarberg / Eurasian beaver (Castor fiber) portrait, Telemark, Norway, June

Orsolya Haarberg / Eurasian beaver (Castor fiber) sniffing, Telemark, Norway, June

Juan Carlos Munoz / Male Gelada baboon (Theropithecus gelada) showing his teeth. Simien Mountains, Ethiopia, Feb 2010

Anup Shah / African Lion (Panthera leo) head portrait of juvenile male, showing teeth in aggressive display, Masai Mara National Reserve, Kenya. April

Anup Shah / Hippopotamus (Hippopotamus amphibius) males fighting in pool, Masai Mara National Reserve, Kenya. February

Anup Shah / Hippopotamus (Hippopotamus amphibius) males fighting in pool, Masai Mara National Reserve, Kenya. February

Anup Shah / Hippopotamus (Hippopotamus amphibius) males fighting in pool, Masai Mara National Reserve, Kenya. February

Anup Shah / Hippopotamus (Hippopotamus amphibius) males fighting in pool, Masai Mara National Reserve, Kenya. February

Anup Shah / Nile crocodile (Crocodylus niloticus) attacking a Thomson's gazelle (Eudorcas thomsonii) as it crosses the Mara River. Masai Mara National Reserve, Kenya, October 2009

Anup Shah / Nile crocodile (Crocodylus niloticus) attacking a Thomson's gazelle (Eudorcas thomsonii) as it crosses the Mara River. Masai Mara National Reserve, Kenya, October 2009

Anup Shah / Nile crocodile (Crocodylus niloticus) attacking a Wildebeest (Connochaetes taurinus) as it crosses the Mara River. Masai Mara National Reserve, Kenya, October 2009

Andy Rouse / Mountain gorilla (Gorilla beringei) youngster with bad teeth in Susa group, Parc National des Volcans, Rwanda

Edwin Giesbers / Clouded leopard (Neofelis nebulosa) head portrait, yawning, captive

Kevin Schafer / Two Amazon river dolphins / Botos (Inia geoffrensis) swimming underwater in flooded rainforest, one with beak open, Rio Negro, Amazonia, Brazil, July

Alex Mustard / Female Grey seal (Halichoerus grypus) mouthiing the camera lens, Lundy Island, Devon, England, UK. July

Alex Mustard / Male Grey seal (Halichoerus grypus) mouths the camera lens, Lundy Island, Devon, England, UK. North East Altantic Ocean. July

Alex Mustard / Lemon shark (Negaprion brevirostris) in shallow water with reflection at the surface. Little Bahama Bank, Bahamas.

Alex Mustard / Lemon shark (Negaprion brevirostris) in shallow water at the surface, split level. Little Bahama Bank, Bahamas. West Atlantic Ocean.

Alex Mustard / Great white shark (Carcharodon carcharias) portrait, Guadalupe Island, Mexico, Pacific Ocean.

Alex Mustard / Male Great white shark (Carcharodon carcharias) showing scars from hunting, Guadalupe Island, Mexico, Pacific Ocean.

Alex Mustard / Lemon shark (Negaprion brevirostris) at the surface, split level. Little Bahama Bank, Bahamas. West Atlantic Ocean.

Bryan and Cherry Alexander / Close up of Narwhal (Monodon monoceros) in water showing its ivory tooth, Northwest Greenland.

Alex Hyde / Fosa / Fossa (Cryptoprocta ferox) male snarling, dry deciduous forest, Kirindy Forest, Western Madagascar, IUCN vulnerable species. Not available for ringtone/wallpaper use.

Edwin Giesbers / European Brown Bear (Ursus arctos) head portrait, with mouth open, captive.

Bence Mate / Jacare / Yacare caiman (Caiman crocodilus yacare) with young armadillo prey ib its jaws. Pantanal, Brazil. WINNER: Eric Hosking Award portfolio image 3/6 - Wildlife Photographer of the Year 2010

Angelo Gandolfi / Head portrait of a Grey Wolf (Canis lupus) captive.

Ann & Steve Toon / Nile crocodile (Crocodylus niloticus) with jaws wide open, Kruger National Park, South Africa

Sergey Gorshkov / Leopard (Panthera pardus) snarling, Botswana

Jeff Rotman / Great White Shark (Carcharodon carcharias) surfacing with mouth open, Dyer Island, South Africa, Atlantic Ocean.

Jeff Rotman / Great White shark (Carcharodon carcharias) surfacing with mouth open, Dyer Island, South Africa, Atlantic Ocean.

Jeff Rotman / Jewel Grouper / Coral hind (Cephalopholis Miniata) with mouth open, Red Sea, Egypt

Edwin Giesbers / Head portrait of Sumatran tiger (Panthera tigris sumatrae) with face half cast in shadow, with aggressive expression, captive

Piper Mackay / Head portrait of Coyote (Canis latrans) yawning, Bolsa Chica wetlands, Huntington Beach, California, USA

Neil Lucas / Weddell seal {Leptonychotes weddellii} mother with pup on ice, pup yawning, Antarctica

Paul Hobson / Water vole (Arvicola terrestris) Peak District, Derbyshire, UK

Nick Garbutt / Adult male Fosa (Crytoprocta ferox) yawning, on deciduous forest floor. Kirindy Forest, western Madagaascar.

Philip Dalton / Common zebra (Equus quagga) swimming across the Mara River on migration, Masai Mara GR, Kenya

Philip Dalton / Nile Crocodile (Crocodylus niloticus) grabbing Common Zebra (Equus burchellii) as it swims across Mara river during migration, Masai Mara GR, Kenya

Wild Wonders of Europe / Sá / Diamond lizardfish (Synodus synodus) with mouth open showing teeth, Deserta Grande, Desertas Islands, Madeira, Portugal, August 2009

Doug Perrine / Close up of teeth and mouth of Salmon shark {Lamna ditropis} captive, Prince William Sound, Alaska, USA (digitally edited)

Theo Allofs / Celebes Black Macaque (Macaca nigra) dominant male, Sulawesi, Indonesia

Andy Rouse / Nile crocodile (Crocodylus niloticus) chasing Wildebeest (Connochaetes taurinus) during migration crossing, Masai Mara, Kenya, Africa

David Shale / Midwater Bristlemouth fish {Sigmops elongatum} night, 188 - 507m, Mid-Atlantic Ridge, North Atlantic Ocean

David Shale / Fangtooth (Anoplogaster cornuta) portrait, Mid-Atlantic Ridge, North Atlantic Ocean

David Shale / Deepsea Dragonfish {Eustomias monodactylus} with bioluminescent lure, from between 498 and 805m, Mid-Atlantic Ridge, North Atlantic Ocean

David Shale / Lizard fish (Bathysaurus ferox) head portrait, from 2750m / 9022ft, Mid-Atlantic Ridge, North Atlantic Ocean

David Shale / Viper fish {Chauliodus sloani}, Mid-Atlantic Ridge, North Atlantic Ocean

David Shale / Head of Lancetfish {Alepisaurus brevirostris} from Mid-Atlantic Ridge, North Atlantic Ocean

David Shale / Angler fish Melanocetus murrayi, Mid-Atlantic Ridge, North Atlantic Ocean

David Shale / Angler fish (Melanocetus murrayi) Mid-Atlantic Ridge, North Atlantic Ocean

David Shale / Angler fish {Linophryne sp} from the Mid-Atlantic Ridge, North Atlantic Ocean

David Shale / Angler fish (Melanocetus murrayi) Mid-Atlantic Ridge, North Atlantic Ocean

Mark Bowler / Mandrill (Mandrillus sphinx) male showing aggression, captive

Andy Rouse / European Red Fox (Vulpes vulpes) yawning, resting in snow, UK, captive

Steven Kazlowski / Polar bear (Ursus maritimus) trying to bite window of a tundra buggy, with paws against the glass, 1002 coastal plain of the Arctic National Wildlife Refuge, Alaska, October 2005

Andy Rouse / Polar Bear (Ursus maritimus) mother and cub playing in water, Svalbard, Norway, September 2009

Mark Taylor / Maine Coon female cat, Serafin, in fierce defensive posture

Mark Taylor / Border Collie-cross bitch, Bliss, snarling, looking aggressive.

Fiona Rogers / Gelada baboon (Theropithecus gelada) sub-mature male showing aggression by lip flipping, Simien Mountains National Park, Ethiopia, November

Fiona Rogers / Gelada baboon (Theropithecus gelada) male yawning showing teeth, Simien Mountains National Park, Ethiopia, November

Andy Rouse / Leopard (Panthera pardus) yawning, South Africa

Wild Wonders of Europe / Lundgre / Anglerfish (Lophius piscatorius) portrait, Saltstraumen, Bod, Norway, October 2008. WWE INDOOR EXHIBITION Wild Wonders kids book.

Wild Wonders of Europe / Lundgren / Atlantic wolffish (Anarhichas lupus) close-up of mouth, Saltstraumen, Bod, Norway, October 2008

Wild Wonders of Europe / Lundgre / Atlantic wolffish (Anarhichas lupus) looking through hole in rocks, Saltstraumen, Bod, Norway, October 2008 WWE BOOK. WWE OUTDOOR EXHIBITION PRESS IMAGE.

Wild Wonders of Europe / Lundgren / Atlantic wolffish (Anarhichas lupus) approaching Sea urchin, Saltstraumen, Bod, Norway, October 2008

Wild Wonders of Europe / Geslin / Grey seal (Halichoerus grypus) pup lying on its back with its mouth open, Donna Nook, Lincolnshire, UK, November 2008. WWE INDOOR EXHIBITION

Wild Wonders of Europe / Lundgren / Atlantic wolffish (Anarhichas lupus) close-up of face, Saltstraumen, Bod, Norway, October 2008

Wild Wonders of Europe / Lundgren / Atlantic wolffish (Anarhichas lupus) close-up of mouth, Saltstraumen, Bod, Norway, October 2008

Pete Oxford / Female Jaguar (Panthera onca) under anesthetic, having teeth measured as part of the collection of biometric data and physiological samples for a relocation project, captive, Fundacion Santa Martha Ce...

Andy Rouse / Bottlenosed dolphin (Tursiops truncatus) underwater, Caribbean (non-ex)

Andy Rouse / Hippopotamus (Hippopotamus amphibius) showing aggressive behaviour, South Africa

Andy Rouse / Hippopotamus (Hippopotamus amphibius) aggressive posture, South Africa

Wild Wonders of Europe / Widstrand / Wild Eurasian wolverine (Gulo gulo) Kuhmo, Finland, July 2008

Wild Wonders of Europe / O. Haar / Arctic fox (Vulpes / Alopex lagopus) barking, dark summer phase, Hornstrandir, Iceland, July 2008

Wild Wonders of Europe / O. Haar / Arctic fox (Vulpes / Alopex lagopus) barking in a wild flower meadow, dark summer phase, Hornstrandir, Iceland, July 2008. WWE INDOOR EXHIBITION

Wild Wonders of Europe / O. Haar / Arctic fox (Vulpes / Alopex lagopus) dark summer phase, Hornstrandir, Iceland, July 2008

Wild Wonders of Europe / O. Haar / Arctic fox (Vulpes / Alopex lagopus) barking in a wild flower meadow, dark summer phase, Hornstrandir, Iceland, July 2008

Wild Wonders of Europe / Lesniewski / Alpine marmot (Marmota marmota) aggressive behaviour, Hohe Tauern National Park, Austria, July 2008

Mary McDonald / Mountain gorilla {Gorilla beringei} silverback male yawning, Volcans NP, Rwanda.

Wild Wonders of Europe / Lundgren / Atlantic salmon (Salmo salar) male, River Orkla, Norway, September 2008

Bruno D'Amicis / Hippopotamus (Hippopotamus amphibius) giving yawn threat, Gojeb river, Kaffa Zone, Southern Ethiopia, East Africa December 2008

Andrew Parkinson / Grey seal {Halichoerus grypus} two adolescents play-fighting among the breaking waves, Lincolnshire, UK

Andrew Parkinson / Red fox {Vulpes vulpes} wild adult male chewing food scavenged at a well used car park. Lancashire, UK Not available for ringtone/wallpaper use.

Doug Perrine / American alligator (Alligator mississippiensis) with mouth open, split level, Big Cypress National Preserve, Florida Everglades, USA

Doug Perrine / American alligator (Alligator mississippiensis) mouth closed but teeth showing, split level, Big Cypress National Preserve, Florida Everglades, USA

Doug Perrine / American alligator (Alligator mississippiensis) with mouth open, split level, Big Cypress National Preserve, Florida Everglades, USA

Doug Perrine / Snout of approaching American alligator (Alligator mississippiensis) Big Cypress National Preserve, Florida Everglades, USA

Bernard Castelein / Grey seal (Halichoerus grypus) yawning on beach, Helgoland, Germany. Second Place in the Comedy Award of the Terre Sauvage Nature Images Awards 2016.