Lemuridae

Characteristics

Lemurids are medium-sized arboreal primates, ranging from 32 to 56 cm (13 to 22 in) in length, excluding the tail, and weighing from 0.7 to 5 kg (1.5 to 11.0 lb). They have long, bushy tails and soft, woolly fur of varying coloration. The hindlegs are slightly longer than the forelegs, although not enough to hamper fully quadrupedal movement (unlike the sportive lemurs). Most species are highly agile, and regularly leap several metres between trees. They have a good sense of smell and binocular vision. All but one species (the ring-tailed lemur) lack a tapetum lucidum, a reflective layer in the eye that improves night vision. Among mammals, activity cycles are either strictly diurnal or nocturnal, however, these can widely vary across species. In general, lemur activity has evolved from nocturnal to diurnal. Some lemurs are also cathemeral, an activity pattern where an animal is neither strictly diurnal nor nocturnal.

Lemurids are herbivorous, eating predominantly fruits and leaves, with some species consuming nectar, gums, and insects. However, the composition of their diets varies greatly depending on the species. Most lemurids have the dental formula 2.1.3.32.1.3.3. Some subfossil records have contributed to the knowledge of the currently extant lemurs from the Holocene by showing the changes in their dental records in habitats near human activity. This demonstrates that lemur species such as the ring-tailed lemur and the common brown lemur were forced to switch their primary diet to a group of secondary food sources.

With most lemurids, the mother gives birth to one or two young after a gestation period of between 120 and 140 days, depending on species. The ruffed lemur species are the only lemurids that have true litters, consisting of anywhere from two to six offspring. They are generally sociable animals, living in groups of up to thirty individuals in some species. In some cases, such as the ring-tailed lemur, the groups are long-lasting, with distinct dominance hierarchies, while in others, such as the common brown lemur, the membership of the groups varies from day to day, and seems to have no clear social structure.

Some of the lemur traits include low basal metabolic rate, highly seasonal breeders, adaptations to unpredictable climate and female dominance. Female dominance is expressed in lemurs with the females and males being sexually monomorphic and females having priority access to food. Lemurs live in groups of 11 to 17 animals, where females tend to stay within their natal groups and the males migrate. Male lemurs are competitive to win their mates which causes instability among the other organisms. Lemurs are able to mark their territory by using scents from local areas.

A number of lemur species are considered threatened; two species are critically endangered, one species is endangered, and five species are rated as vulnerable.

Habitat

The highly seasonal dry deciduous forest of Madagascar alternates between dry and wet seasons, making it uniquely suitable for lemurs. Lemur species diversity increases as the number of tree species in an area increase and is also higher in forests that have been disturbed over undisturbed areas. Evidence from the subfossil records show that many of the now extinct lemurs actually lived in much drier climates than the currently extant lemurs.