Merryn Thomas,Merryn Thomas / Catamarans taking part in the Extreme 40 catamaran racing series in Cardiff Bay, Cardiff, Wales, UK, September 2012.

Alex Mustard / 2020VISION / Basking shark (Cetorhinus maximus) feeding on plankton in the surface waters around the island of Coll, Inner Hebrides, Scotland, UK, June. 2020VISION Book Plate. Did you know? The largest Basking sha...

David Shale / Female Anglerfish fanfin seadevil (Caulophryne jordani) - Deep sea species from Atlantic Ocean, found at 700-3000m.

Mark Carwardine / Great white shark (Carcharodon carcharias) underwater, Guadalupe Island, Mexico (North Pacific)

Doug Perrine / Great white shark jaws open at surface {Carcharodon carcharias} South Africa (Non-ex).

Brandon Cole / Great white shark (Carcharodon carcharias) attacking below surface. Dyer Is, South Africa NOT FOR SALE IN USA, DIGITALLY ENHANCED

Anup Shah / Nile crocodile holding newly hatched young in mouth {Crocodylus niloticus} Kenya

DOC WHITE / Blue whale underwater close-up of head and mouth feeding with pouch inflated, Mexico

Anup Shah / Cheetah female yawning with cub looking into her mouth (Acinonyx jubatus) Masai Mara NR, Kenya

Shane Gross / Humpback whale (Megaptera novaeangliae) portrait, Moorea, French Polynesia, Pacific Ocean.

Klein & Hubert / Nile crocodile (Crocodylus niloticus) close up of jaw and teeth, Chobe River, Botswana, Africa.

Andy Murch / Lemon shark (Negaprion brevirostris) surfacing with open mouth. Tiger Beach, Little Bahama Bank, Bahamas.

Andy Murch / Great hammerhead shark (Sphyrna mokarran) mouth wide open, feeding in shallow water, surrounded by fish. South Bimini Island, Bahamas.

Shane Gross / Cunner (Tautogolabrus adspersus) pair in Eelgrass (Zostera marina) bed. Newfoundland, Canada. September.

Pal Hermansen / Oystercatcher (Haematopus ostralegus) landing on coast in midnight sun. Lofoten, Norway. July.

Nick Garbutt / Walrus (Odobenus rosmarus) amongst group hauled out on shore. Spitsbergen, Svalbard, Norway. July.

Shane Gross / Face portrait of a Great hammerhead shark (Sphyrna mokarran) off Bimini, Bahamas.

Shane Gross / Southern stingray (Dasyatis americana) female underside showing the mouth and gills.The Bahamas.

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.

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.

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 / 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.

Pal Hermansen / Brown bear (Ursus arctos), two showing aggression at night. Finland. August.

Klein & Hubert / Hippopotamus (Hippopotamus amphibius) opening mouth in river - detail upper jaw, nostrils and lips, Luangwa National Park, Zambia

Tui De Roy / Nazca booby (Sula granti) in flight at dusk. Punta Suarez, Espanola Island, Galapagos.

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 / Smooth trunkfish (Lactophrys triqueter), portrait. Bonaire, Dutch Caribbean.

David Fleetham / Great barracuda (Sphyraena barracuda) with three parasitic Copepods at end of upper jaw. Hawaii.

Tony Wu / Asian sheepshead wrasse (Semicossyphus reticulatus), male in white breeding colouration. Niigata Prefecture, Honshu, Japan. June.

Tony Heald / Hippopotamus (Hippopotamus amphibius) splashing in pool in evening light. Mana Pools National Park, Zimbabwe.

Alex Mustard / Striped mackerel (Rastrelliger kanagurta) shoal swimming with open mouths, filtering for zooplankton. Marsa Shouna, Port Ghalib, Marsa Alam, Egypt. Red Sea

Steven David Miller / Emu (Dromaius novaehollandiae) juvenile with beak open to catch a leaf, Cleland Wildlife Park, South Australia, March. Captive.