Video: Bat makes good use of hairy tongue

The hairy bristles on the tongue of a particular bat that feeds on nectar help it draw up the sweet liquid. Now the precise way in which those bristles work has been glimpsed for the first time using high-speed video.

By filming Glossophaga soricina at a high frame rate, Cally Harper and colleagues from Brown University in Providence, Rhode Island, have captured how hair-like structures lining the tongue actively change shape. The tiny projections usually lie flat and were thought to increase the tongue’s surface area in a static way. But the researcher’s footage reveals how their veins fill with blood as the tongue extends, increasing the length of the tip by 50 per cent (see video above).

The strategy is likely to have developed to help the bats gather nectar more efficiently. “As the hairs extend, they create little spaces between the rows that trap nectar,” says Harper. “This means the bat can draw up a greater column of nectar.”

Since hovering close to a flower uses up a lot of energy, other nectar-eating bats have also evolved strategies that exploit tongue action. The rare Ecuadorian bat Anoura fistulata, for example, has a tongue that is up to 1½ times its body length, proportionally the longest of any mammal. This gives it exclusive access to tubular flowers that bats with shorter tongues cannot feed from.


The speed with which G. soricina can change its tongue’s length and texture could inspire new technology. The researchers say the mechanism could be developed to help miniature surgical robots unclog arteries or explore conditions in the stomach.

Journal reference: PNAS, DOI: 10.1073/pnas.1222726110