capillary action elastic micropumps humming birds Interesting Nature nectar University of Connecticut
Hummingbirds : Now a model for micropumps too!
For many years now, scientists have been studying the hummingbird for its flying abilities. Their acrobatic flight is a great model for aeronautical engineers to develop air-crafts for the the future. While everybody concentrated on the wing action, dynamics of the air flow below and over them and the structural differences between humming birds and other fliers to figure out what makes these birds such special fliers, there was something that we had wrongly presumed many years ago, waiting to be discovered about these wonderful birds.
Since the year 1833, we have been assuming that humming birds feed themselves using capillary action. This means, that bird dips its beak into the flower nectar and waits for nectar to slow rise along its longish beak, much like what happens when you sip a cola with a straw, except that you are actually using your mouth to sip in the cola but the humming bird simply waits for the nectar to reach its mouth.
There are two issues with this theory. One Scientific and other non-scientific. Let's go to the scientific one first. Lapping up nectar using capillary technique would take a lot of time, something that simply does not fit in, given the fact we have seen humming birds never ever dwell on a flower for very long. The second one being that waiting for capillary action is a lazy man's job, a route probably a sloth would take. If you have seen the effort these little beings put into flying, there is no way you would expect them to take the capillary route to feed themselves.
It is strange that nobody noticed these anomalies earlier but researchers at the University of Connecticut decided to look into this with the best tool that modern technology can currently offer, the slow motion cameras. Led by researcher Alejandro Rico-Guevara, researchers used slow motion cameras to analyze the feeding styles of different humming birds in Connecticut, Texas, California, and even Ecuador and Brazil. The set up of the experiment involved creating transparent artificial flowers (a process that took five long years) that would allow cameras to capture the events inside the flower. What the researchers found can be summarised in this short clip below.
A humming bird's tongue works very much like a straw but instead of using sucking air like we do, the tongue itself contracts to pull the nectar up. This action is so quick that the bird manages to consume up to 10 drops of nectar in less than 15 milli seconds. In scientific terms, the term would be called an elastic micro pump, and the frequency of the micropump in humming birds would be around 20 Hz or 20 to and fro motions in a single second. Needless to say, hummingbird tongues will now become models to bring in improved efficiency to the micro pumps we are currently using.
Rico-Guevara A, Fan TH, & Rubega MA (2015). Hummingbird tongues are elastic micropumps. Proceedings. Biological sciences / The Royal Society, 282 (1813) PMID: 26290074
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