Tarsiers: Strange and Threatened Primates of Southeast Asia
Tarsiers are strange primates with huge eyes that look too big for their face. Each eye is approximately the size of the tarsier’s brain. The animal's thin and elongated fingers and toes have large adhesive pads at their tips, making them look swollen. Tarsiers also have very long and powerful hind legs that are folded up when they aren’t being used. Their strange appearance often reminds people of Yoda, the Jedi master in the Star Wars movies.
In the wild, tarsiers live only on the islands of Southeast Asia. They are generally nocturnal, although they may be active at dawn and dusk as well. They make their home in trees or sometimes in shrubs. Here they climb and leap with ease. They catch most of their food—insects and other small animals—in the trees. They also sleep, mate, and have their babies in the trees.
There is still a lot that is unknown about the natural life of a tarsier. Unfortunately, the populations of many species of the animal are in trouble. These species need our help in order to survive.
Biological Classification of Tarsiers
Tarsiers are our distant relatives. Like us, they belong to the order Primates and the suborder Haplorhini. They belong to the infraorder Tarsiiformes while humans belong to the infraorder Simiiformes, however. Monkeys and apes are classified in the same infraorder as us. This reflects their greater similarity to humans with respect to their body structure and other factors.
It should be noted that alternate classification systems exist. There is still some disagreement about how the different types of primates should be classified. It seems to be agreed that although tarsiers are primates, they are not as closely related to us as monkeys and apes are.
According to the latest classification scheme, three groups of tarsiers exist: the western tarsier (genus Cephalopachus), the eastern tarsier (genus Tarsius) and the Philippine tarsier (genus Carlito). Each genus contains different species and subspecies.
A tarsier's soft fur is grey or brown and may have buff or reddish patches. Fur color isn’t a reliable way to distinguish the species, though. They differ in features such as body size, size of their eyes, limb proportions, and vocalizations. Another difference is the length of the tail tuft. A tarsier has a long tail that is hairless except for a tuft at the end.
In May 2017, scientists announced that they had discovered two new species of tarsiers on the island of Sulawesi in Indonesia. Before this discovery, there were often said to be eighteen species of tarsiers in existence. There is some disagreement about how the animals should be classified, however.
Tarsiers are found in Malaysia, Indonesia, and the Philippines. They live in forests and treed areas of various types. They also inhabit areas with shrubs or bamboo plants. The animals are sometimes seen in grasslands but seem to use these areas only to travel from one habitat to another.
The primates are often found clinging to a trunk or branch only around six feet above the ground. They sometimes move higher in the trees or leave a tree and come to the ground. They move through the trees mainly by climbing and leaping. They also walk on all four legs and have been observed hopping on their hind legs.
Physical Appearance of the Animals
Tarsiers are small animals. Although they are sometimes said to be the world’s smallest primate, that honor actually goes to the Madame Berthe’s mouse lemur of Madagascar. This mouse lemur has an average weight of 1.1 ounces and a head plus body length of 3.6 inches. The pygmy tarsier is also a tiny primate but is slightly bigger that the mouse lemur. It weighs about 2 ounces and has a head plus body length of about 3.8 inches. The bigger tarsiers may reach around 5.2 inches in length (not counting the tail) and about 5.4 ounces in weight.
The tarsier has the largest eyes relative to its body size of any mammal. In some types, the eyes are not only large but also bulging. The eyes can’t rotate, but the animal can turn its head almost 180 degrees in each direction. This feature gives it a 360 degree view of the world and enables it to leap backwards.
Hands and Feet
The third finger is the largest of the digits in the hand. Most of the tarsier's digits have nails, but there are grooming claws on the second and third toes.
The name “tarsier” comes from the elongated tarsal bones in the animal’s feet. The big tarsal bones, the long hind legs, which are about twice as long as the animal's head and body, and the strong leg muscles make the tarsier a very good leaper.
Tarsiers need their large eyes to help them see in the dark. Unlike the eyes of many other nocturnal animals, tarsier eyes lack a tapetum lucidum. The tapetum lucidum (or simply the tapetum) is a light-reflecting layer behind the retina at the back of the eyeball. The retina is the part of the eye that detects light.
When light strikes the retina of an animal with a tapetum, some of the light is absorbed. Some passes through the retina and hits the tapetum, however. It’s then reflected back to the retina, which absorbs some of the reflected light. The tapetum therefore gives the retina two chances to absorb light rays, helping the animal see better in the dark. Tarsiers need their large eyes to see at night since they don’t have a tapetum lucidum to help their vision.
The Philippine tarsier is said to have the largest eyes in proportion to its body size of any animal on the planet. The giant squid (genus Architeuthis) or perhaps the colossal squid (Mesonychoteuthis hamiltoni) has the largest eyes in the world with respect to the physical size of the eye.
Diet of a Tarsier
The independent movement of a tarsier's ears helps the animal to locate its prey. Its long hind legs provide a powerful thrust for its leaps. Tarsiers often leap on to the prey to catch it. The Philippine tarsier has even been observed catching insects in the air, using its hands as a cage.
The tarsier is the only primate that is entirely carnivorous. Its diet consists mainly of insects, such as crickets, beetles, and termites, but it will also eat small frogs, lizards, crabs, snakes, birds, and even small bats and fish. It eats live prey and often keeps its eyes closed as it chews.
Most tarsiers seem to be social animals, but the degree of closeness and social interaction varies according to the species. Although the animals generally live in groups, the space between the group members during their various activities varies. The most social animals snuggle together, groom each other, and play with each other. They may also share food.
The animals sleep in tangled vegetation or in tree cavities. They sleep alone or with one or more companions, depending on the species. The Philippine tarsier is considered to be a solitary animal and sleeps on its own, though it's sometimes seen near other members of its species when it's awake.
Tarsiers are vocal animals and produce a wide variety of sounds. Some male-female pairs sing sunrise duets together before they go to sleep. Researchers have found that the spectral tarsier of Indonesia makes 15 different sounds in addition to the morning duet. These sounds include a variety of alarm calls, contact sounds, and food calls. Tarsiers have an excellent ability to hear and can detect sounds with a very high pitch.
Tarsiers are territorial. They patrol their territory and advertise it with scent marking and vocalizations. The animals have scent glands on their lips and abdomens. Urine, feces, and fluids from their reproductive tracts also contain smelly chemicals that serve to mark a territory or communicate with other animals in the same group. Tarsiers may group together to chase potential invaders away.
During the day, a tarsier frequently furls its ears (rolls or folds them up) and then unfurls them. The animal indicates fear by keeping its ears furled. It shows aggression by crouching with an open mouth and lunging or by standing on two legs.
Reproduction and Lifespan
Mating behavior varies. Some species appear to be monogamous, with one male mating with one female. In other species, a male is believed to mate with several females.
Gestation lasts five or six months. Only one baby is born. The babies are large at birth and weigh 20% to 33% of the adult's weight. Their eyes are open and their fur has developed. The youngsters are able to climb almost immediately after they are born. The mother carries her baby around in her mouth, however.
The young tarsier develops rapidly. Weaning takes place when the baby is about eighty days old. In at least some species, other females help the mother to take care of the baby.
The lifespan of the different tarsier species is uncertain. In the wild, some individuals are believed to live for twenty years or more. The lifespan is generally much shorter in captivity. This is the opposite trend to that seen in many other animals. Generally, when an animal is protected in captivity, it lives longer than it does in the wild.
IUCN Red List Categories
LC: Least Concern
NT: Near Threatened
CR: Critically Endangered
EW: Extinct in the Wild
Animals classified in the Vulnerable, Endangered, or Critically Endangered category are said to be threatened.
Population Status of Tarsiers
Predators of tarsiers include owls, tree snakes, monitor lizards, civets, and feral cats. Some humans hunt the animals for food. Habitat destruction for agriculture and human settlement is the biggest threat to their survival, however, as it is for so many endangered animals.
Tarsiers sometimes travel through agricultural areas. Here farmers may kill the animals, unaware that they aren't eating the crops but are instead eating the insect pests feeding on the crops. Political unrest has destroyed some suitable habitats for the animals. Another problem is that the animals are captured for the pet trade. They are kept in cages in some places so that tourists can get a good view of them.
The IUCN (International Union for Conservation of Nature) maintains a "Red List" that identifies the population status of different species. The tarsier species surveyed by the IUCN have been classified in the Near Threatened, Vulnerable, Endangered, or Critically Endangered categories of the Red List.
The Tarsier Foundation
In general, tarsiers don't do well in captivity and have a high death rate. They sometimes bang their heads against the bars of their enclosure repeatedly, injuring themselves. Some people keep captive tarsiers in large and natural habitats, however. These people have been more successful in breeding the animals and in keeping them relatively happy.
The Philippine Tarsier Foundation is one organization that is trying to keep the animals physically and mentally healthy and to breed them. The organization also aims to learn more about the animal's behavior, conserve the habitat of the wild animals, and educate the public.
Apart from the western tarsier, all tarsiers used to be classified in the genus Tarsius. Today the Philippine tarsier is often placed in the genus Carlito. Some sources still retain the original genus name, however. The word "Carlito" refers to Carlito Pizarras. It honors his efforts to protect tarsiers and his successful breeding of captive animals. Pizarras is associated with the Tarsier Foundation. He's often known by the name of Nong Lito and is sometimes called "The Tarsier Man" because of his conservation efforts.
Potential Conservation Problems
The writer of the National Geographic article referenced below has been to the Philippine Tarsier Foundation's facility and to another conservation organization's facility in the area. He made the following observations.
The animals in the Tarsier Foundation's habitat have a large area to explore. This means that there is no assurance that a visitor will see the animals, but the primates lead a relatively natural life.
The animals in the other conservation organization's habitat are apparently more restricted in their movement. They have trees to climb. Unfortunately, the writer says that during his visit people crowded around each tree that contained tarsiers and placed their camera lenses very close to the animals in order to take photos. The area was also noisy due to the sound of a chainsaw. Both of these situations would likely have been stressful for the animals. To be fair, it should be said that the conditions that the writer observed may not have been typical or may have been deliberately changed at some point after his visit.
Conservation organizations and people committed to tarsier protection are badly needed in order to save the wild populations of the animal. I think that it's important that people take into account the animal's abilities and needs during a conservation project, however.
Tarsiers are fascinating primates and a valuable contribution to the fauna of the world. I hope the situation improves for those groups and individuals that need help.
- Information about the tarsier from the National Primate Research Center, University of Wisconsin - Madison
- Philippine tarsier facts from The Tarsius Project
- Information about Carlito Pizarras and his efforts to save tarsiers from Motherboard
- Facts about "The Tarsier Man" from National Geographic
- Status of Tarsius syrichta from the IUCN
- Newly-discovered species look like Yoda from Star Wars from Mongobay
© 2011 Linda Crampton