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Tarsiers

Locomotion

Moving somewhat like a small, furry frog, a tarsier can leap from small branch to small branch. In order to do this efficiently, the tibia and the fibula (the two lower leg bones) are fused about halfway down their length, giving the leg more strength. Tarsiers also have elongated ankle bones, which helps them leap, and which gives them their name, tarsier, a reference to the tarsal, or ankle, region. The legs are much longer than their arms.

These curious little nocturnal creatures dart around the undergrowth and low trees, keeping out the A tarsier clinging to a narrow tree branch. Photograph by Alan G. Nelson. The National Audubon Society Collection/Photo Researchers, Inc. Reproduced by permission. realm of the larger animals until they want to leap across the ground to gather up prey. Tarsiers are carnivorous, eating insects and small lizards. They have fat pads on the tips of their thin fingers and toes that help them cling to trees. These primates probably do not build nests.

Tarsiers have large bulging eyes, which close quickly for protection if large insect prey comes near. The eyes also face forward, providing binocular vision, an aid in catching insects at night. The animal's large ears can also be folded for protection. Their eyes do not move in their head, but they can turn their heads in a full half circle, like an owl. This fact accounts for the belief, recorded in Borneo, that tarsiers have detachable heads. The brain of some tarsier species weighs less than a single eye. Their big ears constantly move, listening for sounds of danger.

Tarsiers form family groups consisting of the male, the female, and their young. Each family stays in its own territory, and fusses loudly if another tarsier enters it. After a 180-day gestation, the female produces a single, fairly mature infant. The offspring rides either under its mother's abdomen or in her mouth. When she is off hunting, she may leave it in a safe place. The young can hunt on its own by the age of one month old, when it is also ready to leap.

There are only three species of tarsier in a single genus, Tarsius. All are endangered to some degree, and their ranges do not overlap.

The Mindanao or Philippine tarsier (T. syrichta) lives on several Philippine islands, where its forest habitat is being destroyed. The Western, or Horsfield's tarsier, T. bancanus, lives on Sumatra, Borneo, Java, and the nearby islands, and has been protected in Indonesia since 1931. The middle finger of its hand is amazingly long, almost as long as its upper arm.

The spectral, eastern, or Sulawesi tarsier (T. spectrum), lives in three areas of Sulawesi (formerly Celebes) and nearby islands. Unlike the other species, the spectral tarsier has scales on a skinny tail, rather like a mouse. There is the possibility that another species, T. pumilus, still exists in the mountains of central Celebes.

Over the years, many attempts have been made to domesticate tarsiers. However, without a continuous source of live food, these primates quickly die.


Resources

Books

Knight, Linsay. The Sierra Club Book of Small Mammals. San Francisco: Sierra Club Books for Children, 1993.

Napier, J.R., and P.H. Napier. The Natural History of the Primates. Cambridge: MIT Press, 1985.

Napier, Prue. Monkeys and Apes. New York: Grosset & Dunlap, 1972.

Peterson, Dale. The Deluge and the Ark: A Journey into Primate Worlds. Boston: Houghton-Mifflin, 1989.

Preston-Mafham, Rod, and Ken Preston-Mafham. Primates of the World. New York: Facts on File, 1992.


Jean F. Blashfield

KEY TERMS

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Binocular

—Using two eyes set so that their fields of vision overlap, giving the ability to perceive depth.

Dental comb

—A group of lower incisor teeth on most prosimians that have moved together into a horizontal position to form a grooming tool.

Diurnal

—Refers to animals that are mainly active in the daylight hours.

Nocturnal

—Active in or related to nighttime.

Additional topics

Science EncyclopediaScience & Philosophy: Swim bladder (air bladder) to ThalliumTarsiers - Locomotion