Tarsiers are haplorrhine primates of the family Tarsiidae, which is itself the lone extant family within the infraorder Tarsiiformes. Although the group was once more widespread, all the speciesliving today are found in the islands of Southeast Asia.
Pygmy tarsiers differ from other species of tarsiers in terms of their morphology, communication, and behavior. The differences in morphology that distinguish pygmy tarsiers from other species of tarsiers are likely based on their high altitude environment.
All tarsier species are nocturnal in their habits, but like many nocturnal organisms, some individuals may show more or less activity during the daytime. Based on the anatomy of all tarsiers, they are all adapted for leaping even though they all vary based on their species.
Ecological variation is responsible for differences in morphology and behavior in tarsiers because different species become adapted to local conditions based on the level of altitude. For example, the colder climate at higher elevations can influence cranial morphology.
Gestation takes about six months, and tarsiers give birth to single offspring. Young tarsiers are born furred, and with open eyes, and are able to climb within a day of birth. They reach sexual maturity by the end of their second year. Sociality and mating system varies, with tarsiers from Sulawesi living in small family groups, while Philippine and western tarsiers are reported to sleep and forage alone.
Tarsiers tend to be extremely shy animals.
Tarsiers have never formed successful breeding colonies in captivity. This may be partly due to their special feeding requirements.
A sanctuary near the town of Corella, on the Philippine island of Bohol, is having some success restoring tarsier populations. The Philippines Tarsier Foundation (PTFI) has developed a large, semiwild enclosure known as the Tarsier Research and Development Center. Carlito Pizarras, also known as the “Tarsier man”, founded this sanctuary where visitors can watch tarsiers up close in the wild (naturally without touching them). As of 2011, the sanctuary was taken care of by him and his brother. The trees in the sanctuary are populated with nocturnal insects that make up the tarsier’s diet.
The conservation status of all tarsiers is vulnerable to extinction. Tarsiers are a conservation dependent species meaning that they need to have more and improved management of protected habitats or they will definitely become extinct in the future.
The 2008-described Siau Island tarsier is regarded as Critically Endangered and was listed among The World’s 25 Most Endangered Primates by Conservation International and the IUCN/SCC Primate Specialist Group in 2008. TheMalaysian government protects tarsiers by listing them in the Totally Protected Animals of Sarawak, the Malaysian state in Borneo where they are commonly found.
The phylogenetic position of extant tarsiers within the order Primates has been debated for much of the past century, and tarsiers have alternately been classified with strepsirrhine primates in the suborder Prosimii, or as the sister group to the simians (=Anthropoidea) in the infraorder Haplorrhini. Analysis of SINE insertions, a type of macromutation to the DNA, is argued to offer very persuasive evidence for the monophyly of Haplorrhini, where other lines of evidence, such as DNA sequence data, remain ambiguous. Thus, some systematists argue the debate is conclusively settled in favor of a monophyletic Haplorrhini. In common with simians, tarsiers have a mutation in the L-gulonolactone oxidase (GULO) gene which confers need for vitamin C in the diet. Since the strepsirrhines do not have this mutation and have retained the ability to make vitamin C, the genetic trait which confers the need for it in the diet would tend to place tarsiers with haplorrhines.
At a lower phylogenetic level, the tarsiers have, until recently, all been placed in the genus Tarsius,while it was debated whether the species should be placed in two (a Sulawesi and aPhilippine-western group) or three separate genera (Sulawesi, Philippine and western groups). Species level taxonomy is complex, with morphology often being of limited use compared to vocalizations. Further confusion existed over the validity of certain names. Among others, the widely used T. dianae has been shown to be a junior synonym of T. dentatus, and comparably, T. spectrum is now considered a junior synonym of T. tarsier.
In 2010, Colin Groves and Myron Shekelle suggested splitting the genus Tarsius into three genera, the Philippine tarsiers (genus Carlito), the western tarsiers (genus Cephalopachus), and the eastern tarsiers (genus Tarsius). This was based on differences in dentition, eye size, limb and hand length, tail tufts, tail sitting pads, the number of mammae, chromosome count, socioecology, vocalizations, and distribution. The senior taxon of the species, T. tarsier was restricted to the population of a Selayar island, which then required the resurrection of the defunct taxon T. fuscus. Their classification, which includes several newly described species, is as follows: