The genus Tarsius is the only genus in the family Tarsiidae. This small nocturnal primate genus consists of 10 tarsier species including; T. dentatus, T. fuscus, T. lariang, T. pelengensis, T. pumilus, T. sangirensis, T. supriatnai, T. tarsier, T. tumpara, and T. wallacei (Groves, 2018). Tarsiers are recognized by their large, beady, reddish-orange eyes and tiny stature. They weigh between 80 and 150 grams (Welman, 2017) and have an average body length of 12 centimeters (Merker, 2008). All species experience sexual dimorphism and females tend to be smaller than males. The fossil record of tarsiers dates to between 34 and 56 million years ago, in the Eocene era (Zijlstra, 2013). (Groves, 2018; Merker and Yustian, 2008; Zijlstra, et al., 2013)
Tarsiers inhabit tropical forests and islands of Southeast Asia. The island archipelagos of Southeast Asia include Sumatra, Borneo, Sulawesi, the southern Philippines, and smaller neighboring islands. There are 3 clades of living Tarsius species; western tarsiers, Philippine tarsiers, and Sulawesi tarsiers (Driller, 2015). These clades are composed evolutionarily and geographically, as some species are only found on certain islands or in particular regions. Fossils of Eocene and Miocene tarsiers are found in China, Thailand, and southern Pakistan (Zijlstra, 2013). (Driller, et al., 2015; Zijlstra, et al., 2013)
Tarsiers strictly inhabit forests of Southeast Asia. They reside in both primary and secondary habitats. These arboreal primates are found in forests that range in density and agriculture from island to island. Tarsiers main mode of locomotion is leaping from tree to tree. Tarsiers, being noctural, sleep during the daylight and predominantly roost in dense vegetation (Merker, 2008). Vegetation includes shrubs, bamboo, palm, dense thickets of grass, bush, thorn scrubs, and secondary habitats on plantations for logging and growing coffee, nutmeg, coconut, or coca crops (Gron, 2010) (MacKinnon, 1980). (Gron, 2010; Merker and Yustian, 2008; Zijlstra, et al., 2013)
Of living primates, Anthropoidea are most closely related to Tarsius (Ross, 2000). There is strong debate regarding Tarsius phylogeny. Tarsiers were once accepted to be of the Strepsirrhini suborder, grouped with Lemuroidea and Lorisidae (Wiesemüller, 1999) because of their similar appearance, small stature, and nocturnal nature. It is now widely accepted that tarsiers are members of the suborder haplorrhine, grouped with anthropoids (Ross, 2000). Based on phylogenetic research, including molecular data, tarsiers are more closely related to humans and apes then lemurs and lorises. Some scholarly articles suggest dividing the genus into 3 and some references reflect this attempted revised taxonomy. This taxonomic discrepancy is strongly supported by data collection of physiological attributes such as coat colors, tail lengths, and size, as well as molecular data (Groves and Shekelle, 2010). (Groves and Shekelle, 2010; Ross, 2000; Wiesemuller and Hartmut, 1999)
Tarsiers are small furry primates with large red eyes, small dentition, and short limbs and hands relative to other primates (Groves, 2010). Tarsier eye size, relative to body size, is the largest of any mammal and directly correlates to their nocturnal behavior (Gillian, et al. 2016). Tarsier dentition indicates an insectivorous diet, but some species will prey on small birds and rodents, crabs, frogs, bats, or snakes (MacKinnon, 1980). Their pelage is mostly grey, with hues of red, yellow, or brown (Gron, 2010). Tarsius species that inhabit different geographic ranges may exhibit differences in coat color, eye size, dentition, limb proportions, and hair length of tails or heels (Gron, 2010). Tarsiers are sexually dimorphic, where females are smaller in size than males (Welman et al, 2017). Tarsiers vary in size, ranging from 80-150 grams (Welman et al, 2017) and 10-15 centimeters long (Merker and Yustian, 2008). Tarsiers possess a unique spinal column that permits the ability to turn their heads almost 360 degrees. Other unique adaptations include the claws on their second and third digits, padded fingers, and long tarsal bones at their heels (Gron, 2010). (Gron, 2010; Groves and Shekelle, 2010; MacKinnon and MacKinnon, 1980; Merker and Yustian, 2008; Welman, et al., 2017)
Some species of Tarsius remain in lifelong groups of both males and females, while in other species the males and females rarely interact and even occupy different geographical ranges (Van Shaik and Kappeler, 1997). Some tarsier species enact mating rituals of "duetting", or mating calls that entail one party chattering out and another responding with a similar chatter. Some species that live in groups demonstrate alloparental care, where members occasionally look after another member’s young. Other species practice monogamous pair mating, where only parents will interact with their offspring. Mating pairs are territorial, while individuals in social species are often not (MacKinnon, 1980). Tarsier juveniles often have an orange tinge to their coat hair (Shekelle and Nietch, 2008). Juveniles grow to half the size of an adult tarsier in about 3 months, but are still smaller than adults until about 2 years of age (MacKinnon, 1980). (MacKinnon and MacKinnon, 1980; Shekelle and Nietch, 2008; Van Schaik and Kappeler, 1997)
Tarsiers have 2 mating seasons, in 6 month intervals. They exhibit mating calls referred to as "duets" to find and monitor mate ranges. All species designate a spot to roost in dense vegetation, usually either in pairs or groups. Occasionally young males seeking a group or mate will be alone for a period of time. Some species that stay in groups will let males join. Other species form groups that are exclusively male or female, and the two sexes only come into contact to breed. Females give birth to one offspring at a time (MacKinnon, 1980). (MacKinnon and MacKinnon, 1980)
For the first three weeks of an infant tarsier's life, it is common for the mother to carry them in their mouths whenever they move. In pair-bonded species fathers also carry infants in their mouths. While mothers hunt, the infants are often left on a tree branch for intervals of time. In a monogamous pair both parents will visit the infant during this time. In groups other group members might make brief visits to check up on the infant while the mother is away. Once the infant is about a month old it begins hunting on its own, but remains in the group and within visible range. Females often remain in their parental group throughout their life, unless forming monogamous pairs. Males often leave to live alone or join other groups between 1 to 2 years of age (MacKinnon, 1980). (MacKinnon and MacKinnon, 1980)
Longevity and lifespan has not yet been established for many species of Tarsius. Any evidence of captive lifespan is not directly applicable to wild tarsier lifespan. The longest reported lifespan in captivity is over 17 years. The oldest individual caught in the wild is estimated at 10 years old. Tarsier behavior changes due to old age between 14 and 16 years of age. Signs of advanced aging may include graying of hair around the face and dental wear (Shekelle and Nietch, 2008). (Shekelle and Nietch, 2008)
Tarsiers are nocturnal mammals that awake around sunset and spend the nights foraging for insects, eating, traveling between trees, resting, and socializing. Socialization includes grooming each other, scent marking, vocalizing (including duetting), and playing (Gursky, 1998). Males travel longer distances and occupy a larger area, while females hunt more efficiently and consume more insects (Neri-Arboleda et al, 2002). Tarsiers are both monogamous and polygynous. Some live in pairs, groups of variable size, and some males may live alone. (Gursky-Doyen, 2010). (Gursky, 1998; Gursky-Doyen, 2010; Neri-Arboleda, et al., 2002)
Tarsiers communicate through vocalization and scent marking. Vocalizations include high pitched whistles and chattering melodies referred to as duets. High-pitched whistles are varied from simple calls to predator warnings. Some tarsiers have distinct vocalizations to mob, or ward off, a predator (Gursky-Doyen 2010). The duet vocalizations are likely a mating call to lead males to females. Scent marking on trees is used to attract mates and warn off competitors by marking territory (Neri-Arboleda, 2002). (Gursky-Doyen, 2010; Neri-Arboleda, et al., 2002)
Tarsiers consume an exclusively carnivorous diet. Their diet is mostly insectivorous, but some species will prey on small birds and rodents, crabs, frogs, bats, or snakes (MacKinnon, 1980). Vision adaptations allow for hunting at night, through dense areas of forests (Welman et al, 2017). Limb adaptions allow for quick leaping locomotion between trees while capturing prey. They hunt prey on the ground, in the air, and on tree branches and leaves (Gron, 2010). Tarsiers capture methods typically include grabbing with strong, long fingers or leaping onto prey (Gron, 2010). (Gron, 2010; Welman, et al., 2017)
The primary predators of tarsiers are monitor lizards, civets, snakes, and diverse birds of prey. In the presence of bird predators, individuals vocalize and disperse to hide. When in the presence of a terrestrial predator, such as a snake, individuals “mob” the threat. When mobbing, all individuals respond to a threat with vocalizations as each repeats lunging towards and retreating from the predator (Gursky, 2002). Recent studies suggest predation by domestic animals as habitats grow smaller, and people who capture and sell (Shekelle and Nietch, 2008) or who erroneously consider them pests in farmland (Canete, 2003). (Canete, 2003; Gursky, 2002; Shekelle and Nietch, 2008)
Tarsier niches are largely as predator and prey. Their presence affects the population size of organisms that they feed on and of those who feed on them. They are host to many different endo- and ectoparasites, including mites and intestinal worms (Shekelle and Nietch, 2008). (Shekelle and Nietch, 2008)
Tarsiers draw crowds of eco-tourism, trophy hunters, and animal collectors. Some natives to Southeastern Asia, where tarsiers reside, make a living off of the attraction they draw (Canete, 2003). (Canete, 2003)
Like most primates, some parasites and diseases can be passed from tarsiers to humans. Although some agriculturalists consider them pests, this is a misconception because they do not negatively impact crops or farmland (Canete, 2003). (Canete, 2003)
Habitat loss and deforestation contributes to a decline in tarsier populations (Merker and Yustian, 2008). Currently, tarsiers reside in many protected areas. T. bancanus, T. dentatus, and T. tarsier are considered vulnerable. Tarsius syrichta is considered near threatened. Tarsius pelengensis and T. sangirensis are considered endangered. Tarsius tumpara is considered critically endangered. Tarsius lariang, T. pumilus, and T. wallacei are listed as data deficient. Tarsiers are protected through international treaties (Shekelle et al, 2018). (Merker and Yustian, 2008; Shekelle, et al., 2018)
Four fossil species are known. Specimen are dated from the middle Eocene of China, middle Miocene of Thailand, Oligocene of Egypt, Miocene of Lybia, and Eocene of Myanmar (Zijlstra, 2013). Because of the interest toward dividing the genus into 3, some species are referred to as the attempted revised taxonomic names including the genera Carlito and Cephalopachus . Molecular data and physiological differences noted by Groves and Shekelle suggest this may be true. There may be some cryptic species of Tarsius yet to be discovered (Groves and Shekelle, 2010). (Groves and Shekelle, 2010; Zijlstra, et al., 2013)
Sabrina Archuleta (author), Colorado State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
uses sound to communicate
living in landscapes dominated by human agriculture.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).
uses smells or other chemicals to communicate
helpers provide assistance in raising young that are not their own
active at dawn and dusk
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
A substance that provides both nutrients and energy to a living thing.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
An animal that eats mainly insects or spiders.
animals that live only on an island or set of islands.
parental care is carried out by males
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
found in the oriental region of the world. In other words, India and southeast Asia.
the business of buying and selling animals for people to keep in their homes as pets.
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
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