Monday, December 28, 2009

Big-eyes Lemur

 

Lemurs are primates endemic to the island of Madagascar and smaller surrounding islands, such as the Comoros, where they were likely introduced by humans. Molecular genetics indicates that they reached Madagascar after it broke away from mainland Africa, possibly by "rafting" across the ocean on large clumps of vegetation. While their ancestors were displaced in the rest of the world by monkeys and apes, the lemurs were safe from competition on Madagascar and differentiated into a number of species. These range in size from the tiny 30 gram (1 oz) Madame Berthe's Mouse Lemur to the 10 kilogram (22 lb) Indri. Larger species, some of which weighed up to 240 kg, have all become extinct since humans settled on Madagascar. Typically, the smaller lemurs are nocturnal, while the larger ones are diurnal.

The small cheirogaleoids are generally omnivores, eating a variety of fruits, flowers and leaves (and sometimes nectar) as well as insects, spiders and small vertebrates. The remainder of the lemurs - the lemuroids - are primarily herbivores, although some species supplement their diet with insects.

Except for the Indri, all lemurs have long tails that they use for communication with each other and balance when leaping between trees. They have opposable thumbs and long toes adapted for gripping tree branches. Lemurs have nails rather than claws on all digits except the second toe of each hind foot, which has a toilet-claw for grooming. All lemur species have a tapetum, the reflective layer over the retina that enhances night vision.Lemurs are thought to have limited color vision.Lemurs depend heavily on the sense of smell and have large nasal cavities and moist noses.

Unlike most other primates, lemur species that live in groups have a matriarchal society (i.e., females are dominant over males). Most lemur species are arboreal and traverse the canopy by vertical clinging and leaping or quadrupedalism, with the exception of the Ring-Tailed Lemur, which spend more time on the ground than other species.