BBC Nature - Aye aye ‘heats up’ middle finger. "Madagascar’s mysterious aye aye warms up its extra-long finger when searching for dinner, scientists have found. The lemur, the world’s largest nocturnal primate, taps its specialised middle finger on tree trunks to find nutritious beetle larvae.
Studying thermal images, researchers found that the digit was colder than the others but warmed by up to 6C during foraging. Scientists suggest that the aye aye saves energy by keeping the digit cool.”