Franco Banfi / Blue shark (Prionace glauca) with fishing hook caught in mouth and Pilot fish (Naucrates ductor), Pico Island, Azores, Portugal, Atlantic Ocean
Shane Gross / Southern stingray (Dasyatis americana) female underside showing the mouth and gills.The Bahamas.
Nick Garbutt / Puma (Puma concolor puma) young male standing with mouth open. Estancia Amarga, near Torres del Paine National Park, Patagonia, Chile. December.
Danny Green / Polar bear (Ursus maritimus) male walking across frozen landscape. Svalbard, Norway, April 2019.
Danny Green / Polar bear (Ursus maritimus) male in snow. Svalbard, Norway, April.
Danny Green / RF - Polar bear (Ursus maritimus) male walking through snow covered landscape, mountains in background. Svalbard, Norway, April (This image may be licensed either as rights managed or royalty free.)
Andres M. Dominguez / Hawfinch (Coccothraustes coccothraustes) perched on branch amongst Hawthorn (Crataegus sp) berries. Sierra de Grazalema Natural Park, Cadiz, Spain. February.
Morley Read / Slow motion clip of a Linnaeus' sipo snake (Chironius exoletus) with open mouth, part of threat display, Amazon rainforest, Orellana Province, Ecuador.
Milan Radisics / Aerial shot of a confluence of three tributaries flowing over black sand at the mouth of the Affall River, Landeyjar area, Southern Iceland, August 2018.
Jordi Chias / Leopard seal (Hydrurga leptonyx) with mouth open, Antarctic Peninsula, Antarctica.
Nick Hawkins / Grey seal (Halichoerus grypus) opening mouth close up off Bonaventure Island, Gulf of Saint Lawrence, Quebec, Canada. September.
Nick Hawkins / Fishing ropes wrap around the head and mouth, damaging the baleen of a severely entangled North Atlantic right whale (Eubalaena glacialis) in the Gulf of Saint Lawrence, Canada. Fishing gear entanglem...
Shane Gross / American crocodile (Crocodylus acutus) with open mouth amongst Seagrass (Alismatales). Gardens of the Queen National Park, Cuba.
Franco Banfi / Striped marlin (Tetrapturus audax) feeding on Sardine (Sardinops sagax). Magdalena Bay, Baja California Sur, Pacific Ocean, Mexico.
Eric Baccega / Chimpanzee juvenile (Pan troglodytes schweinfurthii) in a tree. Kibale National Park, Uganda. January.
Tony Wu / View down the throat of a male Zoarchias major eelpout (Zoarchias major) that has opened its mouth during a confrontation with another male. Yamaguchi Prefecture, Japan. Pacific Ocean.
Tony Wu / Two male Zoarchias major eelpouts (Zoarchias major) engaged in a mouth-to-mouth confrontation. Yamaguchi Prefecture, Japan, Pacific Ocean.
Tony Wu / Zoarchias major eelpout (Zoarchias major) with her mouth wide open. Yamaguchi Prefecture, Japan, Pacific Ocean.
Stefan Christmann / Emperor penguin (Aptenodytes forsteri) male feeding chick aged a few days. Atka Bay, Antarctica. August. Sequence 1/2.
Stefan Christmann / Emperor penguin (Aptenodytes forsteri) male feeding chick aged a few days. Atka Bay, Antarctica. August.
Stefan Christmann / Emperor penguin (Aptenodytes forsteri) chick begging for food, on parent's feet. Atka Bay, Antarctica. August.
Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two chicks aged six to eight weeks brooding on parents' feet, one vocalising. Atka Bay, Antarctica. September.
Mark Carwardine / Aerial view of Fin whale (Balaenoptera physalus) lunge-feeding, with mouth open and throat pouch distended, southern Sea of Cortez (Gulf of California), Baja California, Mexico.
Paul Hobson / Parrot snake (Leptophis ahaetulla) in aggressive pose with mouth open. Costa Rica.
Paul Hobson / Keel-billed toucan (Ramphastos sulfuratus) perched on branch with beak open. Laguna del Lagarto, Alajuela, Costa Rica.
Paul Hobson / Red fox (Vulpes vulpes), two cubs play fighting. Sheffield, England, UK. May.
Paul Hobson / Wood warbler (Phylloscopus sibilatrix) singing whilst perched on branch, silhouetted at dawn. Sheffield, England, UK. May.
Pal Hermansen / Brown bear (Ursus arctos), two showing aggression at night. Finland. August.
Nick Upton / Female House spider (Tegenaria sp.) at the mouth of her tubular silk retreat in an old stone wall, Somerset, UK, September.
Klein & Hubert / Hippopotamus (Hippopotamus amphibius) opening mouth in river - detail upper jaw, nostrils and lips, Luangwa National Park, Zambia
Klein & Hubert / Hippopotamus (Hippopotamus amphibius) charging in Luangwa river, close up of mouth and teeth, Zambia
Tui De Roy / Nazca booby (Sula granti) in flight at dusk. Punta Suarez, Espanola Island, Galapagos.
Jurgen Freund / Timelapse of a Scolymia coral (Mussidae) feeding, lit with a UV light, Cairns, North Queensland, Australia.
Alex Mustard / Tiger cardinalfish (Cheilodipterus macrodon) male mouth brooding a clutch of eggs behind his sharp teeth. Gubal Island, Egypt. Strait Of Gubal, Red Sea.
Suzi Eszterhas / Giant panda (Ailuropoda melanoleuca) sitting with Bamboo in background. Shenshuping Panda Base, Wolong Nature Reserve, Wenchuan, Sichuan Province, China. Captive.
David Fleetham / Great white shark (Carcharodon carcharias), two below surface. Guadalupe Island, Mexico.
David Fleetham / Great white shark (Carcharodon carcharias) breaking surface with mouth open. Guadalupe Island, Mexico.
David Fleetham / Clark's anemonefish (Amphiprion clarkii), pair tending to egg mass placed beside the protection of an anemone. Yap, Micronesia.
David Fleetham / Ring-tailed cardinalfish (Ostorhinchus aureus), male protecting and incubating eggs in mouth, Philippines.