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The Bengal slow loris: Cuddly with a chance of venom

A Bengal slow loris with a baby clinging on to her back. Photo: Wiki Commons

A Bengal slow loris with a baby clinging on to her back. Photo: Wiki Commons  

Slow lorises may look cute but will bite anyone stupid or ignorant enough to try touching them

The focus of Swapna Nelaballi’s research was a cute tailless creature, the size of a well-fed house cat, called the Bengal slow loris. None of the eight species of slow lorises reciprocates affectionate human cuddling and will bite anyone stupid or ignorant enough to try, not even sparing celebrities such as Lady Gaga. Their sharp teeth spill blood but also infect the wound with venom. Besides the platypus, slow lorises are the only venomous mammals.

The stinky oily secretion from glands on the inner surface of loris elbows is harmless but becomes toxic when mixed with its saliva. Smearing this nasty concoction on itself and its young puts off nocturnal mammal predators and even insect parasites. The venom, similar to allergy-causing proteins in cat dander, can cause a severe allergic reaction in humans.

Nelaballi, however, had no reason to worry about being bitten during her study at Trishna Wildlife Sanctuary, Tripura. She was content to gaze up at the forest canopy by the light of a headlamp that made the loris’ large round eyes reflect bright, fiery red. “You cannot confuse them with anything else,” she says.

Liquid diet

Despite the potency of the venom that can kill its rivals, the Bengal slow loris does not use it to overcome prey as it lives on an almost entirely liquid diet. It snacks on fruits, insects and bird eggs occasionally, but unlike the south Indian and Sri Lankan slender loris, its staple is plant sap and gum. It rouses itself from sleep after nightfall and climbs down head first from the forest canopy. With its closely spaced lower incisors and canines that biologists call ‘toothcomb’, it gouges deep holes in the trunks of trees and lianas.

Not any tree will do. The primate favours particular species such as belliric myrobalan, climbing wattle, and elephant rope tree, and it selects specific specimens of those species much as we choose the best fruits in the market. Some trunks sport more than a hundred ‘taps’ while others are barely marked. Nelaballi watched a loris tear a new cavity for over 30 minutes. “It’s rare to see one start afresh,” she says. When it goes to work, it holds its posture stock-still for several minutes without suffering cramps because of its unique blood circulation.

Most often, instead of ripping fresh holes every night, the slow loris remembers the location of existing ones, visiting them as frequently as twice a night. With its long pointed tongue, the primate drinks up sap that drips from these injuries. Viscous gum collects slowly, which it scrapes and chews. While the watery liquid is easy to digest, the enlarged cecum in its gut processes the carbohydrate-rich gums.

Stickler for routine

Late in the dry season, when the wild guava (unrelated to the common edible fruit) blooms at night, the slow loris abandons its habitual diet and favourite trees to bury its face in the pom-pom-like flowers to sip the sweet nectar. Nelaballi knew before the study to expect the creature to live off plant secretions, but she was surprised by how much time it spent at it.

The Bengal slow loris is a stickler for routine, always using the same routes to reach the same dining trees, a boon to the researcher during her fieldwork. If she arrived late, she knew where to find her subject.

The night after a heavy storm, she noticed a thin branch used by a loris had snapped. The animal paced back and forth, distressed by this unexpected obstacle on its highway. Reluctant to find an alternative route, it climbed on to the broken limb only to have it crash to the ground. The primate landed on all fours like a cat and stood stunned for a moment before shinning up the tree and walking along another branch to reach its dinner. And a new routine was born.

The writer is not a conservationista but many creatures share her home for reasons she is yet to discover.

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Printable version | Feb 24, 2020 11:31:09 AM | https://www.thehindu.com/sci-tech/energy-and-environment/cuddly-with-a-chance-of-venom/article30828847.ece

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