Hummingbird tongues are super weird. They are so long that when not in use, they are coiled around the bird's skull. They are forked at the end, and each fork curls up into a not-quite-closed tube. The birds use these weird tongues to dip into flower nectar at speeds up to 18 times a second. In 1833, scientists proposed that hummingbirds drink by capillary action, but that has been disproven. Margaret Rubega and Alejandro Rico-Guevara set out to study the exact mechanics of how hummingbirds drink. That involved building glass flowers and teaching hummingbirds to drink from them. Then a high-speed camera revealed what their tongues did.
As the bird sticks its tongue out, it uses its beak to compress the two tubes at the tip, squeezing them flat. They momentarily stay compressed because the residual nectar inside them glues them in place. But when the tongue hits nectar, the liquid around it overwhelms whatever’s already inside. The tubes spring back to their original shape and nectar rushes into them.
The two tubes also separate from each other, giving the tongue a forked, snakelike appearance. And they unfurl, exposing a row of flaps along their long edges. It’s as if the entire tongue blooms open, like the very flowers from which it drinks.
When the bird retracts its tongue, all of these changes reverse.
The tongue acts like a tiny pump, pumping tiny bits of nectar into the tiny bird. Ed Yong gives us an explanation of what happens when a hummingbird drinks at the Atlantic (with video). The original scientific paper is more technical, but it contains diagrams of hummingbird tongues. -via Metafilter
(Image credit: Mdf)