Editor's note: “WHAT IS...” is a new feature of Primate Nooz which is aimed at some of our younger and more precocious readers in which we plan to ask different people in the field of primatology major “What is” questions. We expect the results to be pretty darn exciting, and we hope that before long kids everywhere will be clamoring for their very own copy of the Nooz.  In this issue, we begin with a question that has puzzled mankind for centuries, and to answer it we are fortunate to have Mr. Win Wing Wan, lately of the Beijing Zoo.

By
Mr. Win Wing Wan, lately of the Beijing Zoo

        The inscrutable tarsier is a small, furry, large-eyed primate, generally muscade and/or sennet in color, weighing on average 120g. or 4.25oz. and occupying the approximate ecological niche of an owl.  Tarsiers live only on the spicy islands of Southeast Asia.  Four species are taxonomically recognized: Horsfield's, Philippine, spectral and sulky.  Of these, the sulky tarsier is the best known and the least liked.
          Tarsius irritatus, like the other tarsiers, is only secondarily adapted to a nocturnal life, having many features much more in common with the anthropoids than with the prosimians, such as its proclivity to start small fires to provide light for itself after sunset.  Tarsiers, like anthropoids, have relatively heavy neonates, but the infants are more precocial.
          Solitary ranging pairs of males and females are often synterritorial, and there is a marked degree of both inter- and intra-specific variation in the amount of social contact that is observed.  Tarsiers have large and membranous ears and a tail the distal third of which is slightly tufted.  Their eyes are huge and practically immobile, but they can turn their heads around 180°, thus affording them a wide range of vision.
          Tarsiers derive their name from their elongated tarsal region.  This and the fusion of the tibia and fibula in the lower third of their lengths give the tarsier tremendous leaping ability, which it uses to good advantage in catching the insects that make up 90% of its diet.  Tarsiers have been observed leaping 50m into a tree to grab a cockroach for breakfast.
          Tarsiers have 34 teeth, having lost two of the incisors that are retained by the lemuriformes.  Their long hands are prehensile, with non-opposable thumbs, and their fingers have fleshy digit pads to facilitate clinging to vertical supports.  The eye of the tarsier lacks the tapetum lucidum of the other prosimians.
          In addition to insects, tarsiers eat spiders and lizards, and are preyed upon by owls.  They are primarily arboreal and remain in the trees most of the time.  All digits have small flake-like nails except the 2nd and 3rd digits of the feet, which have toilet claws.  Marking is accomplished by urination, and is a nightly territorial ritual.  Tarsiers rest in an upright clinging posture with the knees tucked under the chin and the tail used as a support.
          Preferred habitat for tarsiers is primary and secondary forest and they typically occupy the lower understory of     (Cont. on page 4)