Tarsiers' eyes are stationary in their orbits requiring that they rotate their heads almost 360 degrees to change their field of visions. Of all the primates, tarsiers have the largest eyes relative to body size with an average eyeball diameter of 16 mm. Tarsius bancanus, one of the five Tarsius species, lives in Borneo and Sumatra. Adults weigh 80-165 g (.17-.36 lb), and have head and body lengths of 8.5-16 cm (3.3-6.3 in). They have small upper bodies, extremely long hindlimbs, and large heads. Tarsiers are nocturnal, feeding on invertebrates and vertebrates, including small poisonous snakes. As vertical clingers and leapers, they can jump distances up to 6 m (18 ft) at a time.