If you end up in a forest in Southeast Asia one night and feel a pair of huge eyes peering out from behind a branch, there’s a very good likelihood it is a tarsier. No larger than a clenched fist, this tiny primate has eyes which are each even larger than its own brain.
This nocturnal primate lives peacefully within the trees of select islands in Indonesia, Malaysia and the Philippines, carrying with it an evolutionary legacy that has remained largely unchanged for tens of thousands and thousands of years.
Fossil evidence shows that tarsiers have existed for roughly 45 million years. Since then, their shape and anatomy have modified so little that they’re also known as “living fossils.”
A primate who defies easy classification
From a scientific viewpoint, tarsiers are amongst probably the most enigmatic primates. They display features resembling those of apes like lemurs, but in addition display distinctive features of haplorhines, a bunch that features monkeys, apes and humans.
Their arboreal lifestyle and dental structure resemble those of monkeys, while their high dependence on vision, ability to specific themselves, and inability to synthesize vitamin C bring them closer to haplorrines.
Since 2010, tarsiers are divided into three types: Carlito within the Philippines, Cephalopes within the west wing and Tarsierwhich incorporates nine species within the eastern region. Differences between species are identified based on a mix of vocalizations, social structure, dental patterns, physical appearance, and geographic distribution.
Nevertheless, this classification stays provisional. Genetic analyzes reveal significant differences between populations, suggesting the opportunity of additional species which have not yet been formally recognized.
The discovery of the Wallace tarsier in 2010 further supports the concept that tarsier diversity has not been fully mapped.
An extreme body built for the night
Tarsiers have a highly specialized anatomy. They are the one fully carnivorous primates, feeding mainly on insects, but they can even hunt small birds, lizards and snakes. Some individuals have even been observed catching prey within the air.
Their necks allow the top to rotate as much as 180 degrees in any direction, providing a large visual view without moving the body. Their legs and tails are long, with extremely elongated ankles.
This structure allows them to leap as much as two meters horizontally and over one meter vertically, which is a crucial adaptation to life in trees.
When breeding, tarsiers again deviate from the everyday pattern of small mammals. A newborn baby can weigh as much as 30 percent of its mother’s body weight.
Gestation lasts about six months, for much longer than in other primates of comparable size. Although the feminine gives birth to just one baby, she has 4 to 6 nipples.
Life on the sting of survival
The tarsier’s entire life takes place within the treetops. Sticky pads on the fingertips help him stick when he sleeps or jumps. He can be very vocal; each species has a particular call, and female and male pairs often vocalize together in a duet-like manner.
However, tarsiers are under an increasing threat. Deforestation and habitat degradation have relegated most species to the endangered or critically endangered categories.
The Siau Island tarsier was once among the many 25 most endangered primates on the planet. Conservation efforts pose a specific challenge because keeping tarsiers in captivity is amazingly difficult and their mortality rate is high attributable to stress.
