10 Terrific Facts About Tarsiers

Tarsiers are little-known nocturnal primates, about the size of a tennis ball. Once more widespread, tarsiers are now limited to the Southeast Asian islands of the Philippines, Malaysia, Brunei, and Indonesia. There are 10 tarsier species and four subspecies, belonging to a sister group of monkeys and apes. Extinction threatens all tarsier species, to some degree.

With a stare like no other animal, super long fingers, velvety soft fur, and the ability to catch insects or even birds with a pounce, they are worth a second look. Here are a few things that make the tarsier a fantastic animal.

1. Tarsiers Have Enormous Eyes

Tarsiers have the largest eyes relative to body size of any mammal. Each eyeball is around 16 millimeters in diameter, which is as large as the tarsier’s entire brain. The eyes are so large that they can’t rotate them. Instead, tarsiers can twist their necks a full 180 degrees in either direction, just like owls. They use this ability to wait silently for prey to approach, rather than moving around to hunt.

The size of their eyes is likely related to the absence of a reflective layer called a tapetum that's typically found on the eyes of other nocturnal animals. Babies are born with their eyes open, ready to climb trees within an hour of birth.

2. They Are Entirely Carnivorous

Tarsiers are the only entirely carnivorous primate. While the specific diet varies with the species, they all have one thing in common: they don’t eat plant matter of any kind. They feast on insects, reptiles like lizards and snakes, frogs, birds, and even bats. They’re serious ambush predators, waiting silently for prey to approach nearby—and can even snag birds and bats right out of the air.

Old texts, based on regional lore, reported that tarsiers eat charcoal. This report is untrue; instead, the tarsiers dig through charcoal to reach bugs.

3. They Have Elongated Appendages

Tarsiers get their name from the extraordinarily elongated tarsus bones in their feet. While the tarsier’s head and body are 4 to 6 inches in length, their hind legs and feet are twice as long. They also have a long, usually hairless tail that adds an extra 8 or 9 inches. Their fingers are extra long to help grasp tree branches, and their third finger is as long as their entire upper arm. The tips of their digits can expand into disk-like adhesive pads that aid them in gripping. This unique anatomy allows tarsiers to be vertical clingers and climbers—and jumpers. They can jump 40 times their body length in a single leap.

4. They Live Close to the Ground

Tarsiers typically reside between 3 and 6.5 feet off the ground. These animals prefer to live in areas of dense, dark vegetation. They need plenty of tree cover, especially for sleeping. They sleep during the day while clinging to a vertical tree branch or bamboo. The thick vegetation of the rainforest and living close to the forest floor provides greater access to insects and other prey. It also shades their sensitive eyes from the sun. They can be found in both old growth and secondary forests, as well as in low scrubby vegetation.

5. There Are Three Types of Tarsiers

There are three types of tarsiers: Eastern, Western, and Philippine. Eastern tarsiers inhabit Sulawesi and the surrounding islands, Philippine tarsiers are limited to the Philippines and have a totally bald tail and hairless feet, while Brunei, Borneo, Indonesia, and Malaysia host populations of Western Tarsiers, which have tails with tufts at the end. The Philippine and Western tarsiers are predominantly lowland species. Eastern tarsiers are spread across many habitats and elevations, except for the pygmy species, which is solely found above 1,600 feet. The pygmy variety was thought to have gone extinct when it wasn't spotted between 1921 and 2008.

6. They Are the Oldest Surviving Primate Group

Tarsiers are some of the oldest primates on the planet, dating back at least 55 million years, with fossil records showing them once spread worldwide, including North America and Europe. The fossil remains of tarsiers indicate a tiny creature of only around an ounce. Eye sockets on these fossils suggest that some were likely active during the day. They do have the long hindlimbs and grasping feet that today's tarsiers use to leap between branches.

7. They Don't Do Well in Captivity

Tarsiers' specific needs in both habitat and prey make captive breeding programs virtually impossible, and only around 50% of tarsiers put into captivity survive. Tarsiers that are stressed or in cages that are too small have suicidal tendencies. Particular stressors are light, noise, humans in their habitat, and being touched. They will bash their thin skulls against trees, the floor, or walls of the cage. Habitat conservation is their only hope. Life expectancy in captivity drops to two to 12 years, as compared to 24 years in the wild.

8. They Perform Duets

Pairs of tarsiers engage in complex duet calls, most likely to occur at sunrise as the tarsiers head to sleep. Scientists believe that the tarsier couple is providing other tarsiers in the area with information about their pair-bond. The duets also may serve to mediate territorial issues. Researchers are interested in these duets because the co-singing may provide insights into the evolution of human language. Tarsiers can produce calls that are in the ultrasonic range, possibly to warn others of humans approaching or predators like snakes or owls.

9. Pygmy Tarsiers Were Believed Extinct

In 2008, scientists located the first population of live pygmy tarsiers (Tarsius pumilus) since collectors obtained specimens in 1930. Measuring only 3 to 4 inches long, including the tail, they are the smallest living tarsiers, about the size of a small mouse. They have thick, curly coats and can wiggle their ears. Pygmy tarsiers aren't as vocal as lowland tarsiers, but scientists speculate they may make high-pitched noises undetectable to human ears.

10. They Are at Risk of Extinction

All tarsier species are vulnerable to extinction due to rapidly shrinking habitats and fragmentation. Oil palm, coconut, and coffee plantations have replaced the dense vegetation that tarsiers need to maintain their numbers successfully. Vulnerability to predation by feral cats and dogs, plus human poaching for food and short-lived pets, add to the issues faced by these animals. Focused and wide-ranging conservation efforts are needed across Southeast Asia to preserve these species.

The Siau Island Tarsier is among the 25 most endangered primates in the world. Not only has their primary habitat been destroyed, but they are also regularly eaten as a snack food.