WHY ARE SLOW LORIS POISONOUS ?
Both sexes of all slow loris species have a gland inside their elbow (brachial gland), which sweats a clear oil. Loris often lick the gland when under stress, then lick their young all over or rub the mixed saliva and oil over their heads. Observations show that the liquid is toxic to leeches and ticks, and repels predators such as Sun Bears. The oil in the gland contains venom that is activated when combined with saliva. This venom is powerful enough to kill mice when injected, and cause severe allergic shock in humans, occasionally resulting in death.
Nekaris et al. (2013) suggest that the poison has developed as a defense against both predation and attacks from rival slow loris during territorial breeding fights. If toxins are sequestered from poisonous saps and beetles, then toxin strength would vary with diet. A slow loris that ate toxic foods, signaled to predators and rival Slow Loris by urine smell, would have a competitive advantage.
The orange arrow points to the brachial gland on the underside of the arm of this male slow loris. This gland secretes a clear poisonous liquid used by slow loris for defense.
MARIANNE NORTH DESCRIBES THE RESULT OF BEING BITTEN BY A SLOW LORIS IN SARAWAK
” A.H. Everett was bitten by a slow loris he had caught and given to a friend. Walking back over the mountains, he felt as if his shirt was throttling him, but found his fingers so swollen he could not unbutton his shirt, and soon fell down in a swoon, remaining there till the morning when some Dyaks found him all puffed up and unable to move or speak. He said that he did not suffer, but was utterly powerless. The Dyaks poured half a bottle of gin down his throat and carried him home and he got well in time. It was all the result of the Slow Loris bite”
Extracted from Marianne North (1892) the botanical artist from her book Recollections of a Happy Life (1892) in which she describes a visit to Sarawak in 1876.
A.H. Everett was an English zoological collector active in Sarawak and northern Borneo.