Nile crocodile (Crocodylus niliticus) on shore of Mara River with open jaws, Masai Mara National Reserve, Kenya, East Africa, Africa

Hippopotamus Amphibius (Hippo), open jaw used as warning by males protecting females, plentiful in the Luangwa River, Zambia, Africa

Nile crocodile (Crocodylus niloticus) with jaws open, Kruger National Park, South Africa, Africa

American alligator (Alligator mississipiensis) with open jaws, Sanibel Island, Florida, United States of America, North America

American alligator (Alligator mississipiensis) with open jaws, Sanibel Island, Florida, United States of America, North America

Sperm whale head-lunging with jaws open. Midriff region of the Gulf of California, Mexico.S(AW)S(Mexico (Pacific))S(sperm whale)S(lunging)

Basking Shark (Cetorhinus maximus) Close up of head. Cornwall, UK. (A4 only).

Yacare Caiman (Caiman yacare, Caiman crocodilus yacara), Pantanal, Mato Grosso do Sul, Brazil, South America

Spectacled caiman (Caiman crocodilus yacare), open mouth with leeches, animal portrait, Pantanal, Mato Grosso, Brazil, South America

Museum near Moose Jaw, Saskatchewan, Canada

Nile crocodile (Crocodylus niloticus) with a captured catfish, Chobe River, Chobe National Park, Botswana, Africa

Close-up of Nile crocodile (Crocodylus niloticus) with open jaws, Grumeti Serengeti Tented Camp, Serengeti National Park; Tanzania

Caribbean, Bonaire, Great Barracuda (Sphyraena Barracuda).

Mexico, Guadalupe Island, Great White Shark (Carcharodon carcharias) biting down on bait above ocean surface.

Hawaii, This galapagos shark (Carcharhinus galapagensis) can reach twelve feet in length and is listed as potentially dangerous. It has been attracted with bait and has broken the surface with a splash.

Mexico, Guadalupe Island, Great white Shark (Carcharodon carcharias) facing steel cage.

Mexico, Guadalupe Island, Great White Shark (Carcharodon carcharias) near safety steel cage.

Caribbean, Bonaire, Great Barracuda (Sphyraena Barracuda).

Micronesia, Yap, Yellow juvenile jacks swim with a grey reef shark, (Carcharhinus amblyrhynchos).

Two hippos, Hippopotamus amphibius, fight each other on land, one with his jaws wide open, the other with bloodied mouth and flanks, Londolozi Game Reserve, Sabi Sands, South Africa