The Javan slow loris is active at night (1) (5) (8) (9) and sleeps in tree hollows or vegetation during the day (8) (10) (12). As its name suggests, this species moves with quite slow, deliberate movements as it walks or climbs hand-over-hand along branches (7) (8) (10).
The diet of the Javan slow loris is quite varied, and includes sap, flowers, fruit, insects, bird eggs and even small vertebrates, such as lizards and small mammals (5) (7) (8) (10) (12) (13). Like other slow lorises, the Javan slow loris is also able to gouge trees with its teeth to feed on gum (10) (12) (13). Despite its slow, stealthy movements, this species can strike quickly to seize prey with its hands (7) (8) (9) (13).
The Javan slow loris is usually seen alone or in pairs (7) (12), but has also been known to sleep in small groups (12). In general, slow lorises are not thought to have a distinct breeding season, and births may occur throughout the year. Male slow lorises are territorial, and do not tolerate the presence of other adult males in their territory (7) (8).
Little specific information is available on the breeding behaviour of the Javan slow loris, but it is likely to be similar to that of other slow loris species. In general, female slow lorises give birth to a single infant after a gestation period of just over six months (8). Both the male and female may take turns at carrying the infant, or it may be left clinging to a branch for short periods while the adults forage (7) (8). Young slow lorises are weaned at about 5 to 7 months old, and reach sexual maturity at around 17 to 24 months. Slow lorises have been known to live for over 26 years in captivity (8).
The only venomous primates, slow lorises produce venom by combining secretions from a gland on the elbow with saliva (3) (7). The exact function of the venom is not known, but it is likely to be involved in protection against predators (3). Adult slow lorises may lick their young to spread the venom over them, possibly to protect them (7), and when threatened a slow loris often covers its head with its arms, allowing it to take in the toxin from its elbow glands (9). The bite of a slow loris can be very painful, and can potentially cause serious allergic reactions in humans (3) (7) (9).