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How hummingbird tongues work

The new science is in on how hummingbirds eat.

You might have heard of the astounding length of the hummingbird’s tongue. To get to the bottom of certain flowers, it is one and a half times the length of the bill in some species, and wraps around the skull. Textbooks on the birds say that these elongated tongues work by capillary action. That’s the force at work when one dips a straw into a glass of water and water moves up inside the straw higher than the level of the water outside. The effect is due to molecular interactions between water and the straw’s surface.

But Alejandro Rico-Guevara and Margaret Rubega at the University of Connecticut, Storrs say that it isn’t so. And they should know. They examined 120 hummingbird tongues in person and watched tongues on slow-motion video doing their thing—and found that their tips (that’s tips plural because the tongue is forked) roll in from the edges, trapping nectar. Think of scooping water up with your hands to get an idea of the effect. The neatest part is that the shape changes all happen passively as the tongue dips in and out of the nectar—no energy expenditure required on the bird’s part (see video).

The paper suggests that this new understanding will affect “models of foraging strategy and energy balance” in the bird, but we here at Nature’s News Blog also note that the information activates the “gee whiz” center of the human brain. And that goes for the authors as well. Rico-Guevara has worked with hummingbirds for years. “I was skeptical about capillarity being the whole story, but I was astonished as well the first time we saw the tongues transforming the way they do!”

If you watch carefully during the first part of this video, supplied by researchers, you can see the forked tongue in action.

The study joins “how snakes slither” and “”http://www.nature.com/nature/journal/v463/n7280/full/463433a.html">how people run" in the annals of recent biomechanics gee whiz center activators.

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