The true, or typical lemurs (Lemuridae) are diurnal primates and thus have relatively smaller eyes than the mouse and dwarf lemurs. Their eyes are golden yellow. Their body is about the size of a domestic cat, but their tail is considerably longer. These lemurs eat fruit, leaves, and some insects. Their social groups vary in size from two to more than 20, and the females tend to dominate the males. The females also are responsible for defense of the group. The females usually bear a single offspring after a gestation period of about 18 weeks. The young lemur rides on its mother's back for several months.
The fluffy, black-and-white striped tail of the ring-tailed lemur (Lemur catta) is present in both males and females, though most lemurs exhibit sexual dimorphism, or different coloring in males and females. When moving, the ring-tailed lemur holds its dramatic tail up in a gentle curve. It also waves it to disperse the chemical released by its scent glands, which are located on its forearms. These glands have tiny spurs that can slash the bark of trees, leaving the slash scented with their territory-marking odor. The ring-tailed male also uses this scent in a strange kind of combat. When two aggressive males confront each other, each rubs its long tail on its forearm scent gland, turns, and waves its smelly tail. Apparently, one of the antagonists finds itself overwhelmed and gives in.
The ring-tailed lemur is about 15 in (38 cm) long, with an 18-20-in (46-51 cm) tail, and weighs about 6-7 lb (2.7-3.2 kg). Although ring-tailed lemurs spend most of their time on the ground (they are the only lemur that does this), they climb trees in their open forest in the early morning to reach the sunlight, which warms them after a chilly night. Because they spend much of their time walking on the ground, they have smooth, leathery palms and soles.
Only the male black lemur (L. macaco) is completely black. Females have a white ruff around their black face and a white chest. The rest of the female's body is reddish brown. The mongoose lemur (L. mongoz) exhibits similar sexual dimorphism. Although males and females are both gray-brown in color, the females have white cheeks and neck, while the males have red cheeks. The widely occurring brown lemur (L. fulvus) is a stay-at-home, rarely moving more than 300 ft (90 m) from its territory, which consists of only a few trees. Within this territory it tends to remain near the tops of the trees. It may be active day or night.
The largest of the true lemurs is the ruffed lemur (Varecia variegata) of eastern Madagascar. It may be 4 ft (1.2 m) long from head to tail and weigh up to 6.5 lb (3 kg). Mostly a black animal, the long, shaggy fur of its ruff may be white or reddish. Its back and part of its legs are also white. Strangely, unlike the other true lemurs, the ruffed lemur has a fairly short gestation period (about 100 days compared to 120-135 days for the other species), and its offspring (often twins) are born too weak to hang onto their mother. She places them in a small fur-lined nest for at least three weeks.
The genus of so-called gentle lemurs (which are no more gentle than other lemurs), Hapalemur, prefers a watery habitat as well as forest. These lemurs live among the reeds located by lakes, and are sometimes good swimmers. They eat the soft heart, or pith, of the reeds, and they also like sugarcane. The gentle lemurs are more thickset than most lemurs. The broad-nosed gentle lemur (H. simus) occurs in only three tiny populations and is close to extinction. The gray gentle lemur (H. griseus) is more widespread but also endangered.
The sportive lemur (Lepilemur mustelinus) received its name because, when threatened, it turns and raises its arms as if preparing to box. In its dry habitat, this lemur eats primarily prickly succulent plants that provide so little nourishment that it eats its own feces to further digest the food (this is known as coprophagy). Unlike most lemurs, the sportive lemur lives a semi-solitary life, with one male in a territory encompassing the smaller territories of several separated females. It is also the only true lemur to have 32 teeth as an adult instead of 36. Recent genetic studies have shown that the sportive lemurs, also called weasel lemurs, of different areas in Madagascar may actually be different enough from each other to represent seven species in a separate family, the Lepilemuridae.