Lemurs are primates that are endemic to the island of Madagascar. They are mostly small-bodied, with a pointy snout, large eyes, and a long tail. They can mostly be found in tall trees, and they are primarily active at night.
The lemurs are divided into 8 families, 15 genera with an approximate count of a hundred existing species. They have a similar appearance with other primates, but they evolved separately from apes and monkeys.
Their evolution has produced a level of species variance competing with that of any other primates. This is due to the highly seasonal climatic condition of Madagascar. About 2,000 years ago, when human habitation was still sparse on the island, lemurs were almost the size of a male gorilla.
Lemurs belong to the strepsirrhini suborder. Similar to other primates in this suborder, they share ancestral traits with other primates. They are popularly confused with ancient primates.
The eight families include the Archaeolemuridae, Cheirogaleidae, Daubentoniidae, Indriidae, Lemuridae, Lepilemuridae, Megaladapidae, and the Palaeopropithecidae.
Description, Distribution and Diversity
Lemurs have various weight classes, and they range from the mouse lemur’s weight of 30 grams to the Indri, which weighs about 9kg.
They also share some usual primate traits at the base of their bodies; divergent digits on their limbs. Most species of lemurs also have nails instead of claws. However, they don’t share the same size ratio of their brain-to-body as theirs is smaller in proportion than other anthropoid primates.
Like other strepsirrhine primates, they possess rhinarium (a wet nose). They are also the most social strepsirrhine primate. They rely mostly on communication mediums such as scents and vocalizations instead of visual signs. They have the ability to display dormancy such as torpor or hibernation because of their slightly low metabolic rate.
Due to how diverse their diets are, it is possible to have two different lemurs species coexisting together in the same habitat because they have different diets. The name lemur is an extract from the Latin word lemures. This means specters or ghosts that were cast out during the Lemuria festival of ancient Rome.
The extreme limitations of resources and seasonal mating are thought to have given birth to three other common lemur traits. They include female social dominance, sexual monomorphism, and male versus male contests. The lemurs’ dentition usually consists of six teeth (2 canines and 4 incisors).
Indrids, sloth lemurs, and monkey lemurs, however, have four teeth due to the loss of a canine or incisor.
The lemurs can exclusively be found on the island of Madagascar and the Comoro Islands, in close proximity to Mozambique. They inhabit mountains, wetlands, spiny forests, dry deciduous forests and rain forests.
The smallest species of lemurs primarily feed on fruits and insects. They are omnivorous creatures. The larger species are more herbivorous in their diet, but the lemurs are highly flexible animals and so are their diet. When very hungry, lemurs can forgo their preferences and opt for anything edible.
Plants make up for most of the lemur diets. Lemurs feed on about 55% of plant species in Madagascar. Most of these plants are trees and shrubs. Some lemurs such as the ring-tailed lemur are also known to consume herbs.
Lemurs are generally seasonal breeders with very brief mating periods. Their birth seasons are determined by the highly seasonal availability of environmental resources. Their mating periods usually last less than three weeks annually.
Also, the vagina of the female lemur opens up only during a few days or hours of her most receptive times on heat. Their narrow opportunities for breeding and availability of resources correlates with their brief gestation periods. It also connects with their quick sexual maturation, low basal rates of metabolism, and the high energy cost of reproduction for the female lemur.
All this leads to a slightly high mortality rate among adult females and a higher proportion of adult males in lemur populations. Lemurs are known to time their breeding and procreation seasons.
This is done so that all weaning seasons are in sync with a period when food is abundant. Weaning takes place before or immediately after the advent of the first permanent molars in lemurs.
Mouse lemurs are capable of fitting their whole breeding cycle into the rainy season. In the case of the larger lemurs, they must lactate for about two months during the dry season. The survival of the infant lemur is hinged on certain factors such as environmental conditions and the mother.
The health, rank, and age of the mother have a huge impact on the infant’s survival chances. Mating behavior can either be monogamous or promiscuous.
Multiple lemur species are facing extinction due to hunting and loss of habitat. In the last two millenniums, a lot of their species have already gone extinct as a result of human habitation and activities on the island of Madagascar. Although local laws help protect lemurs and their forests, but unlawful logging and political instability hinder conservation efforts.
These threats triggered the tremendous drop in their populations, which is now just 2000-2,500 lemurs left in wildlife. They have experienced a 95% decline in their population from 2,000 years back.
The International Union for Conservation of Nature (IUCN) regards lemurs as the world’s most endangered mammals. They noted that almost 90% of all lemur species are facing extinction within the timeframe of the next 20-25 years. Their conservation status is “Critically Endangered.”