Unusual Lemur Heats Up its Foraging Finger

The aye-aye lemur has never been known for its beauty. In fact, this shy and rare animal is considered one of the most hideous in the lemur family and have been surrounded with myth and tales of terror due to its mysterious demeanour. It is the world’s largest nocturnal primate with scraggly black and grey hair, large ears, and long, spindly, claw like fingers. Appearance wise, the aye-aye is what nightmares are made of.

However, despite its creepy fa├žade, the animal is actually quite shy and reclusive, and is a harmless forager that searches for insects hidden deep in the crevasses of trees.

The aye-aye uses its unusually long middle finger to search for insects. It does so by tapping the surface of tree trunks to find the nutritious beetle larvae underneath. After finding the insect, it then bores a hole into the surface and yanks out the beetle larva in order to eat up.

Interestingly enough, scientists have discovered that this long, specialized finger actually heats up while it is foraging for food, going up by at least 6 degrees Celsius. When it is at rest however, the finger is typically cooler than the rest of the body in order to conserve energy.

These new findings were published in the International Journal of Primatology and was lead by the Dartmouth College in New Hampshire US. The study was made primarily to study the surface temperature of delicate structures such as the ones found in an aye-aye’s fingers.

The aye-aye was chosen because its finger is already highly sensitive to vibrations and therefore is the perfect subject for the study. Gillian Moritz, a graduate student who participated in the study under their supervisor Dr Nathaniel Dominy says “It was striking to see how much cooler the third digit was while not in use and how quickly it warmed to match the other digits when engaged in an active foraging task”.

Using heat sensitive equipment, they studied the thermal differences on the animal’s body. The closer the reading is to white, the warmer it is, and the closer it is to black, the cooler it is. The long foraging finger registered as black, while the eyes and ears register as the warmest parts of the aye-aye’s body. However, the finger quickly warms up to match the temperature of the rest of the body as it forages.

While the fingers are generally bad for retaining heat because they are extremities on the body, they typically warm up because it helps the nerve endings become more sensitive to vibrations, which is what the aye-aye uses to heat up its body. This fires up the specialist sense receptors, which are considered relatively costly in terms of energy.

The scientists therefore remark that if the animal is at rest and not using its fingers to tap out its food, it makes sense that it should cool down in order to preserve energy. It also keeps the animal alert.

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