Hummingbirds receive spotlight at fluid dynamics meeting
The abstract for their 13-minute talk says:
We present the results of a combined experimental and theoretical investigation of the drinking technique of the hummingbird. Its long, thin tongue is dipped into nectar approximately 20 times per second. With each insertion, fluid rises along the length of the tongue through capillary action.The New York Times explains further:
While the tongue is open in cross-section, resembling a sliced straw, experiments demonstrate that surface tension serves to close it, with the tongue's zipping front corresponding to the rising meniscus. Supporting theoretical and analogue experimental models of this novel, natural example of capillary origami are developed and explored.
For the latest research, Dr. Bush and his co-workers found that when a hummingbird stuck its tongue into a flower, the tongue, about three-quarters of an inch long, curled up into a cylinder just one twenty-fifth of an inch in diameter because of surface tension.Illustration courtesy of New York Times/Chris Gash
“The hummingbird’s tongue looks like a straw with a slot cut in it,” Dr. Bush said.
Also because of the surface tension, the slot in the cylindrical tongue zips closed, beginning from the tip. The nectar is drawn upward, and the cylinder fills.