Richard Du Toit / Hippopotamus (Hippopotamus amphibius) threat yawning, Khwai River Botswana

Ingo Arndt / Mountain Lion (Puma concolor) female yawning, Torres del Paine National Park, Patagonia, Chile

Ingo Arndt / Mountain Lion (Puma concolor) yawning and stretching, Torres del Paine National Park, Patagonia, Chile

Ingo Arndt / Mountain Lion (Puma concolor) yawning, Torres del Paine National Park, Patagonia, Chile

Graeme Guy/ BIA / African Lion (Panthera leo) male yawning, Kruger National Park, South Africa

Hiroya Minakuchi / Leopard (Panthera pardus) yawning, Samburu National Park, Kenya

Suzi Eszterhas / Giant Panda (Ailuropoda melanoleuca) yawning, native to China

Hiroya Minakuchi / African Lion (Panthera leo) male yawning, Masai Mara, Kenya

Hiroya Minakuchi / African Lion (Panthera leo) male yawning, Masai Mara, Kenya

Hiroya Minakuchi / Leopard (Panthera pardus) mother yawning near cub, Okavango Delta, Botswana

Hiroya Minakuchi / Crabeater Seal (Lobodon carcinphaga) on ice, Paradise Bay, Antarctica

Richard Du Toit / Hippopotamus (Hippopotamus amphibius) large bull threat-yawning in the Khwai River, Botswana