Nectar-Feeding Bat's Long Tongue Becomes Nectar Mop When Engorged With Blood

Posted on May 9, 2013

Mop-like tip of nectar-feeding bat's tongue

Brown University scientists have found that a species of bat, Glossophaga soricina, uses blood flow to reshape its tongue so it can mop up nectar. The researchers call the bat's mop-like tongue a "hemodynamic nectar mop." An image of the tip of the bat's tongue is pictured above.

Cally Harper, a graduate student in the Department of Ecology and Evolutionary Biology at Brown University and lead author of the paper, says the tongue tip is surprisingly clever. She says, "Typically, hydraulic structures in nature tend to be slow like the tube-feet in starfish. But these bat tongues are extremely rapid because the vascular system that erects the hair-like papillae is embedded within a muscular hydrostat, which is a fancy term for muscular, constant-volume structures like tongues, elephant trunks and squid tentacles."

The bag tongue has a mesh of muscle fibers that contract so that the tongue becomes thinner but longer, enabling it to extending farther into the flower. The researchers found that the same muscle contraction simultaneously squeezes blood into the tiny hair-like papillae on the tip of the bat's tongue. The erect papillae flare out and add exposed surface area and width enabling the bat to gather up lots of nectar. The bat tongue could inspire new industrial designs.

Here is Cally Harper explaining the bat's extraordinary tongue:

The findings were reported here in the Proceedings of the National Academy of Sciences.

Photo: Cally Harper in the Brainerd-Swartz Lab/Brown University

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