Enrique Lopez-Tapia / Large flying fox (Pteropus vampyrus) hanging upside down on garden tree. Bali Island, Indonesia.

Enrique Lopez-Tapia / Large flying fox (Pteropus vampyrus) male hanging upside down on garden tree. Bali Island, Indonesia.

Nick Upton / Forest caterpillar hunter (Calosoma sycophanta), a ground beetle hanging upside down as it forages in a Holm oak (Quercus ilex) tree in search of Gypsy moth caterpillar (Lymantria dispar) prey, Bacu G...

Steven David Miller / An Apostlebird (Struthidea cinerea) dangling upside down from a tree branch, Cania Gorge National Park, Queensland, Australia. Others from the group are on the ground. September.

Suzi Eszterhas / Cotton-top tamarin (Saguinus oedipus) feeding on fruit in tree. Northern Colombia.

Lorraine Bennery / Flying fox (Pteropus rufus), roosting, Kirindy Mites National Park, Madagascar, Vulnerable, endemic.

Suzi Eszterhas / Pale-throated Three-toed Sloth (Bradypus tridactylus) male hanging in tree, Sloth Island, Guyana

Suzi Eszterhas / Pale-throated Three-toed Sloth (Bradypus tridactylus) male hanging in tree, Sloth Island, Guyana

Philippe Clement / Lyle's flying fox (Pteropus lylei) male hanging upside down from hind feet in tree, captive, occurs in Cambodia, Thailand and Vietnam,

Staffan Widstrand / Wild Wonders of China / Tibetan macaque (Macaca thibetana) juveniles playing, hanging upside down in tree, Tangjiahe National Nature Reserve, Qingchuan County, Sichuan province, China

Staffan Widstrand / Wild Wonders of China / Tibetan macaque (Macaca thibetana) juveniles playing, hanging upside down in tree, Tangjiahe National Nature Reserve, Qingchuan County, Sichuan province, China

Eladio Fernandez / Caribbean cracker butterfly (Hamadryas amphicloe) resting upside down on tree trunks, Dominican Republic.