There are 3 separate lemur familes, 10 genera, 20 species and 40 subspecies. The ring-tailed lemur (Lemur catta) is known as the "common" lemur, and has light grey fur, a black and white masked face and a ringed tail. The ringed tail, consisting of 13 alternating black and white bands, makes these lemurs easily recognizable and give them their name. Sexes show very little dimorphism; males have slightly heavier heads and shoulders (however this hard to see) and the male scrotum is large, black and pendulous (Haring 2004). Ring-tailed lemurs weigh between 6 1/2 to 7 3/4 pounds, with a head and body length of 10 to 12 inches. They have long hind legs and short forelegs, and they run quadrupedally (on all fours) (San Francisco Zoo 2004).

Lemurs have several vocalizations including a bark, howl (given by males, usually at dusk when settling), meow (an answer to a howl), a scream which can carry 750-1000 m, and clicks and purrs which can carry up to about 1 m (Jolly 1966).

Humans and lemurs both share a mutual forebear, a squirrel-sized mammal that lived in the subtropical forests at least 50 million years ago. It had forward-facing eyes supported by a pillar of facial bone. It had projecting thumbs and fingernails. The anscestors of lemurs first appeared more than 40 million years ago; they rafted across the straight to Madagascar on branches or logs as Madagascar began to separate itself from Africa. Few other mammals made the journey, and the larger-brained monkeys evolved later in Africa (Jolly 1988).