Tarsiers, the World's Tiniest Primates

Small enough to fit in the palm of your hand, tarsiers are sometimes mistakenly called "the world's smallest monkeys," but they are not actually monkeys.

Taxonomic Classification of Tarsiers

Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Primates
Suborder: Prosimii/Haplorrhini
Infraorder: Tarsiiformes
Family: Tarsiidae
Genus: Tarsius
Species: Tarsius syrichta, T. tarsier, several others

There are between six and eight known species of tarsiers, and an additional few subspecies, although sources differ on the exact number since these secretive, nocturnal creatures are difficult to study. Taxonomic classification of tarsiers is also somewhat problematic. Some sources place them in the suborder prosimians, related to bush babies, lemurs and lorises, and they have also been classified as the suborder haplorrhini, or dry-nosed primates, which includes monkeys and apes.

Description and Behavior of Tarsiers

Tarsiers range in size from 3.8-5.2 inches long and weigh only 2-5.4 ounces. They have grey, tan or light brown fur and a long, hairless tail about twice their body length, with a tuft of fur on the end. Their long, narrow fingers have wide pads at the ends to aid in grasping branches.

Like owls, tarsiers can turn their heads 180 degrees in both directions. Most species have eyes that are enormous in comparison to the size of their heads. Their main form of movement is leaping, and some species can jump more than 16 feet. They also climb, hop, and walk on four legs. They are arboreal animals, leaping from tree to tree, and spending little time on the ground.

The diet of tarsiers consists entirely of living prey, and they are the only primates that do not eat any plant material. They are primarily insectivores, often snatching their prey out of the air, and eating a variety of insects including grasshoppers, beetles, butterflies and cockroaches. Some species also eat occasional small vertebrates such as frogs, birds, bats and snakes.

Tarsiers live in small groups, sometimes consisting only of one male and one female. They give birth to one infant at a time, with a gestational period of six months. The babies are very large relative to the body size of the mother, weighing up to 30% of the mother's body weight, the highest ratio of any mammal.

The lifespan of tarsiers in the wild is unknown, but the oldest individual in captivity died at 16 years of age.

Tarsier Range and Habitat

While the fossil record indicates that tarsiers once had a much wider distribution, all known species of tarsiers are now found only in Southeast Asia, on the islands of Borneo, Sumatra, Sulawesi, and the Philippines.

Tarsiers live in a variety of habitats including forests of all types, shrubs, swamps, bamboo and scrubland. They are also found in cultivated or agricultural areas, such as coffee or nutmeg plantations, although they require dense shrubbery in which to sleep.

Tarsiers are Threatened or Endangered Species

The populations of all known tarsier species are decreasing. These precious little animals are threatened due to habitat loss and fragmentation, poisoning by pesticides, and hunting. The critically endangered Siau Island Tarsier has been placed on the list of 25 Most Endangered Primates. Other species are on the IUCN Red List as endangered, near threatened or vulnerable.

Conservation organizations working to help protect tarsiers include the Tarsius Project and the Philippine Tarsier Foundation.

Sources:
Primate Info Net http://pin.primate.wisc.edu/factsheets/entry/tarsier
Animal Diversity Web http://animaldiversity.ummz.umich.edu/site/accounts/information/Tarsiidae.html