Steven Kazlowski / Polar bear {Ursus maritimus} baring teeth at truck window, seen from inside vehicle, Coastal plain of the Arctic National Wildlife Refuge, Alaska.

Anup Shah / Hamadryas baboon male threat display {Papio hamadryas} baring teeth

Danny Green / Coyote (Canis latrans) on snow baring teeth in aggression display. Yellowstone, United States of America, February.

Nick Upton / American miniature horse (Equus caballus) baring its teeth as another grazes nearby, Wiltshire, UK, March.

Ben Lascelles / Common Vampire Bats (Desmodus rotundus) day roosting in a hollow tree, one baring its teeth at the camera. Chaco region, Argentina, October.

Bert Willaert / Mole Rat (Fukomys micklemi) baring its teeth in a threat posture. Belgium. Captive.

Daniel Heuclin / Emerald Tree Boa (Corallus caninus) baring its fangs; head in profile. Controlled conditions. Montagne de Kaw, French Guyana, August.

Edwin Giesbers / Sumatran tiger (Panthera tigris sumatrae) walking, and baring teeth in aggresive display, captive

Laurent Geslin / African Lion (Panthera leo) head portrait of juvenile male snarling and baring teeth in display of aggression, Chobe National Park, Khawai, Botswana, Southern Africa

Konrad Wothe / European Wolf (Canis lupus) pair fighting with one baring teeth, Bavarian Forest National Park, Germany

Patricio Robles Gil / Gelada baboon (Theropitecus gelada) male yawning baring teeth, Simien Mountains NP, Ethiopia

Mitsuaki Iwago / Giant Panda (Ailuropoda melanoleuca), captive bred cub baring its teeth, China