Nick Hawkins / Grey seal (Halichoerus grypus) opening mouth close up off Bonaventure Island, Gulf of Saint Lawrence, Quebec, Canada. September.

Solvin Zankl / Fire Ant (Solenopsis geminata) head of a major worker with mandibles used for opening seeds. Specimen photographed using digital focus stacking

Solvin Zankl / Just three hours after they hatch from the water and moult into mature adults, the male Long-tailed / Tisza mayfly (Palingenia longicauda) perish. Adult mayflies have no mouth opening and no guts. The...

Mitsuaki Iwago / African Lion (Panthera leo) female roaring, Serengeti National Park, Tanzania

Mark Raycroft / Brittany Spaniel (Canis familiaris) with training bumper

Mark Moffett / Tokay Gecko (Gecko gecko) showing underside of feet

Mitsuaki Iwago / Spotted Hyena (Crocuta crocuta) laughing, Serengeti

Shin Yoshino / African Lion (Panthera leo) male roaring, Kenya

Mitsuaki Iwago / African Wild Dog (Lycaon pictus) calling, Serengeti National Park, Tanzania

Gerry Ellis / Ostrich (Struthio camelus), east Africa

Jim Brandenburg / Nile Crocodile (Crocodylus niloticus) mouth defense displaying, South Africa

Mitsuaki Iwago / African Lion (Panthera leo) pride with one female snarling, Serengeti National Park, Tanzania