The opossum has grayish with black fur. Feet and ears tend to be black. The tail is scaly and prehensile. The inner toe on the hind foot diverges widely away from the others making the track similar to that of a human hand.
Opossums are active year-round and inhabit moist woodlands and brushy habitats at low elevations.
They are common to abundant throughout California west of the Sierra Mountains. The preferred habitats include riparian, moist woodlands, brushy habitats, wetlands, agricultural areas, and residential areas that provide abundant food and cover. Water is required for species success so higher concentrations may be found near water sources, especially during dry years. Dense conifer forests and grasslands do not seem to support large numbers. Activity occurs throughout the night from dusk to dawn, peaking at midnight.