Opossums are active largely at night and are non-territorial, solitary creatures. They are not true hibernators, and, except for brief periods during severe weather, they remain active during the winter. The opossum’s rather heavy, scaly, sparsely-furred tail is prehensile and is able to hold, seize and carry objects. They also use their tail for balance and leverage when climbing.
Possum eyes are well adapted to nocturnal life and are quite keen in the dark, even though they are thought to depend as heavily on smell, touch, and hearing for finding food. Opossums walk or run in a slow, hobbling manner, but they climb with agility and are very competent swimmers. Their slow gait and fondness for carrion doubtless contributes to the frequency with which they are killed by cars.
Because opossums do not move very fast, “playing possum” may have evolved as a means of fooling predators, which feed only on live prey. When confronted by a predator the possum’s first line of defense is to hiss, growl, and show its teeth. If the predator is not deterred and the opossum is attacked, it plays dead. While in this catatonic state, the opossum falls on its side and becomes completely limp, with its tongue hanging out of its mouth. It often defecates and may also emit a greenish, foul-smelling substance from its anal glands. During this state, which can last up to six hours, the opossum’s breathing and heart rate decrease.