|Exposed tongue of a|
photo: Dr. Kristiina Hurme
Conventional wisdom among ornithologists held that the hummingbird's tongue used capillary action to draw in nectar. Capillary action describes liquid flowing into narrow spaces due to intermolecular forces, rather than some external forces like gravity.
This past summer, while hummingbirds in North America were gathering nectar in preparation for their migratory journey to equatorial locales, evolutionary biologist and functional morphologist Alejandro Rico-Guevara published the results of a study that suggests the hummingbird's tongue acts like an elastic micro-pump.
Rico-Guevara observed that hummingbirds can draw nectar from a flower in less than a second which, he reasoned, was much too quick to be attributed to the wicking action of intermolecular forces.
Rico-Guevara's slow-motion video posted on YouTube by Science News (above) shows a hummingbird repeatedly extending its tongue into a red drink.
The hummingbird's tongue acts like an elastic micropump.Rico-Guevara's study suggest that the hummingbird's tongue is compressed as it approaches the nectar, then becomes plump as the nectar rapidly hydrates grooves in the tongue.
And the humming-bird that hung
Like a jewel up among
The tilted honeysuckle horns
They mesmerized and swung
In the palpitating air,
Drowsed with odors strange and rare.
And, with whispered laughter, slipped away
And left him hanging there.
― James Whitcomb Riley
- How hummingbirds' tongues work | Science News, YouTube, 18 August 2015.
- Hummingbird, Wikipedia.
- Hummingbird tongues are elastic micropumps, Alejandro Rico-Guevara, Tai-Hsi Fan, Margaret A. Rubega Proc. R. Soc. B 2015 282 20151014; DOI: 10.1098/rspb.2015.1014. Published 19 August 2015.
- Hummingbird tongues are way weirder than we thought, Rachel Feltman, Speaking of Science, Washington Post, 19 August 2015
- Hummingbird tongues may work like micropumps: How nectar rises through specialized grooves has inspired debate, Susan Milius, Science News, 18 August 2015.