Hummingbird drink with forked tongue
May 3, 2011 § Leave a comment
Wired Science has a post on the hydrodynamics of hummingbird tongues, describing the results of a paper that came out this week in PNAS. Apparently, the story until now has been that hummingbirds suck up nectar via capillary action, through tubes along the edges of their tongues. But if this were true, then hummingbirds should seek out medium-strength sugar solutions, around 20-40% sugar:liquid. In fact, hummingbirds prefer higher sugar concentrations. This is now explained by high-speed videos of hummingbird tongues: as the tongue flicks into the sugar solution, it uncurls into two forks (looking rather like tentacles in some parts of the video), which then come together again to trap an aliquot of fluid. Capillary action has essentially nothing to do with it. Many applications to biologically-inspired engineering are suggested, from improved mops to liquid-sipping robots.
Do we now understand how a hummingbird feeds? No: getting the liquid into the mouth via the tongue is one thing, but how the hummingbird swallows that fast is still “considered magic right now”. Or if not magic, at least unexplained.