Lemurs

Lemur Facts

Classification:

• Kingdom: Animalia
• Subkingdom: Bilateria
• Phylum: Chordata
• Subphylum: Vertebrata
• Class:Mammalia
• Order:Primates
• Suborders: Strepsirrhini
• Superfamily: Lemuroidea
• Families: Lemuridae (including brown lemurs, black lemurs, crowned lemurs, red-bellied lemurs, bamboo lemurs, ring-tailed lemurs, mongoose lemurs, ruffed lemurs); Lepilemuridae (sportive lemurs); Cheirogaleidae (dwarf lemurs and mouse lemurs, fork-marked lemurs); Indriidae (avahi or woolly lemurs, indri, sifakas); Daubentoniidae (aye-aye); several extinct families
• Geographical location:Madagascar and adjacent Comoro Islands
• Habitat: Forests (primary or secondary, dry, humid, or rain forests, evergreen or bamboo forests); sometimes also bush, scrub, or savanna edges of humid forests, spiny deserts, and tree plantations
• Gestational period: From 65 days in the dwarf lemur to 175 days in the larger sifaka, indri, and aye-aye
• Life span: Ranges from about nine years in the greater dwarf lemur to twenty-five to thirty years in ring-tailed, brown, and black lemurs
• Special anatomy: A long snout with a sensitive, moist pad (rhinarium); incompletely fused bony eye socket; reflecting retina (tapetum); ancestral dental formula of 2:1:3:3; dental comb in the lower jaw and sublingua (except aye-aye); unfused lower jaw and frontal bone; multiple pairs of breasts; two-section uterus; grooming claw on second toe of foot

Lemurs are primates found only in Madagascar and the Comoro Islands, where they have no competition from other primates except humans. While they were once thought to be ancestral to apes and monkeys due to certain primitive features, genetic evidence suggests this is not the case. Lemurs evolved from early primates and became geographically isolated on the island of Madagascar, where they further evolved separately from all other primates and became greatly diversified to fill various ecological niches, contributing to the unique makeup of the fauna of Madagascar. Humans arrived on Madagascar about two thousand years ago, contributing to extinctions of one third of the island’s species through habitat destruction, hunting, climate change, and perhaps new diseases. Most lemurs are highly endangered.

Most lemurs are arboreal (tree-dwelling), although ring-tailed lemurs spend more time on the ground. Lemurs subsist primarily on three to four food species, consisting of a mix of leaves, fruit, buds, bark, and shoots, but favored foods can vary monthly or seasonally; many species exhibit specialized anatomy or behaviors related to their preferred food source. The golden bamboo lemur tolerates high levels of cyanide in the bamboo shoots. The smaller, nocturnal lemurs and the aye-aye eat more insects, with the aye-aye having unique long fingers for capturing grubs from wood. Several species are cathemeral (active during parts of day and night), and there are also diurnal (day-active) forms, such as ring-tailed lemurs or indris. The diurnal species may have a nocturnal past, because they share certain features with nocturnal lemurs, including seasonal breeding, female dominance, and reliance on scent for communication.

Unique Primates

Lemurs exhibit many types of social organization. They are solitary in smaller nocturnal forms, while larger diurnal or cathemeral forms live in pairs that sometimes congregate in larger groups, usually with 1:1 sex ratios. Lemurs lack strong sexual dimorphism, and if there is a difference, females are larger than males. In social species, females largely dominate males, to the extent that males signal submissiveness to all females independent of context. This unusual primate pattern may be due either to seasonally low food productivity and the resulting reproductive costs, or may be partly a function of extinctions of raptors that preyed on primates.

Lemurs range in size from the pygmy mouse lemur at thirty-one grams (about one ounce) to the indri at seven kilograms (sixteen pounds), although many extinct forms were larger. All lemurs have longer posterior than anterior limbs, and their anatomy reflects their ability to practice vertical clinging and leaping. This is most developed in the sifakas and indris, which generally position themselves vertically while in the trees, leap from tree to tree, and exhibit a leaping, kangaroo-like gait when on the ground.

The great diversity of lemurs, as well as their relationship to other strepsirrhine primates (such as lorises, pottos, and bush babies or galagos), has led to significant disagreement in the scientific community regarding lemur taxonomy. For this reason the number of accepted species varies, and some taxonomic systems have differences at the infraorder and superfamily levels. The most widely accepted families are Lemuridae, Lepilemuridae, Cheirogaleidae, Indriidae, and Daubentoniidae, with several recognized extinct families as well. The aye-aye, the only member of the Daubentoniidae family, in particular posed a challenge to early taxonomists until it was shown to be the most basal of all lemurs, sharing some traits with rodents. The aye-aye has a high brain-to-body ratio and also has incisors that grow throughout its life (as in rodents) resulting in a dental formula of 1-0-0-3. The teeth are used to gnaw on dead wood during searches for grubs that are then removed with a lengthy third finger.

Cheirogaleidae include the fat-tailed and greater dwarf lemurs, primates that hibernate for up to six months during the dry season. Many of the females in Cheirogaleidae, Lepilemuridae, and Lemuridae families carry offspring in their mouths and sometimes park them on branches when active.

Principal Terms

dental comb: forward projecting lower incisors and canines that are used for grooming and feeding

dental formula: denotes the types of teeth in one quarter of the mouth: incisors, canines, premolars, molars

polygyny: males compete for access to several females

primitive: a feature that reflects an ancestral condition rather than those that represent more recent evolutionary changes (derived)

sexual dimorphism: behavioral and anatomical differences between the sexes

sublingua: fleshy plate under the tongue used to clean the dental comb

Bibliography

Bradford, Alina. "Facts about Lemurs." LiveScience, Purch, 1 July 2016, www.livescience.com/55276-lemurs.html. Accessed 6 Oct. 2016.

Duke Lemur Center, Duke U, 2016, www.lemur.duke.edu/. Accessed 6 Oct. 2016.

Falk, Dean. Primate Diversity. New York: W. W. Norton, 2000.

Jolly, Alison. “Pair-bonding, Female Aggression, and the Evolution of Lemur Societies.” Folia Primatologica 69, supplement 1 (1998): 1-13.

Kappeler, Peter M. “Determinants of Primate Social Organization: Comparative Evidence and New Insights from Malagasy Lemurs.” Biological Reviews of the Cambridge Philosophical Society 72, no. 1 (February, 1997): 111-151.

"Lemurs of Madagascar." WildMadagascar.org, Rhett Butler, 2012, www.wildmadagascar.org/wildlife/lemurs.html. Accessed 6 Oct. 2016.

Mittermeier, Russell A., William R. Konstant, David M. Meyers, and Roderic B. Mast. Lemurs of Madagascar. Washington, D.C.: Conservation International, 1994.

Rakotosamimanana, Berthe, Hanta Rasamimanana, Jorg U. Ganzhorn, and Steven Goodman. New Directions in Lemur Studies. New York: Plenum, 1999.

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