Vampire bats know just where to bite for maximum effect by using in-built infrared technology.
Just as heat-seeking missiles home in on targets, so the bats are able to identify the hotspots on warm-blooded prey.
But precisely how the bats sense infrared has not been understood until now.
Scientists in the US discovered the secret after studying vampire bats in South America. They found that nerve endings in three ‘leaf pits’ around the bat’s nose are coated with a sensitive heat-detecting molecule called TRPV1.
Similar molecules on pain-sensing nerve fibres in the tongues, skin and eyes of humans react to the burning chemical capsaicin in chilli peppers.
In vampire bats, evolution has turned the pain sensor into a sophisticated heat-seeking device. Their detectors guide them to the best spot to bite, and their teeth can pierce through the hide of a sleeping animal – normally a cow or goat – without waking it.
Anticoagulant chemicals in the bat’s saliva keep the blood seeping through the open wound as they lap it up.