How Do Fleas Jump So High? It's All In The Toes!
Did you know that fleas, those tiny blood-sucking parasites that make your pet's life miserable, can leap as high as 13 inches or about 200 times their own body weight and, with an acceleration force that exceeds 100 times the force of gravity? Believe it or not, some of the world's leading scientists have not only know that, but have pondered and debated about it, for the last 44 years.
The main area of contention has not been how this tiny insect could generate energy that was 100 times what its muscles could provide to catapult this far and fast - That debate was settled in 1967 by Dr. Bennet Clark, who dissected the insect's legs and discovered that similar to a froghopper, the fleas stored their energy inside a stretchy protein pad called resilin that was connected to their legs.
The debate was how it channels this energy into a giant leap - Dr. Bennet Clark maintained that the insects used just their 'toes' or the foot-like segments at the end of their legs called Tarsus. However, British naturalist Miriam Rothschild argued that they leapt using their kneelike structures or tronchaters.
Dr. Michael Burrows, an insect jumping specialist at the University of Cambridge, finally decided to put this debate to rest, by recording over 51 high energy jumps from 10 hedgehog fleas, using some high-speed recording equipment.
What he noticed was that for most jumps, both the toes (tarsi) and knees (tronchaters) were in contact with the ground, prior to take off. But, in 10 percent of the jumps it was just the toes, that came in contact.
What was interesting is that the jump and the rate of acceleration for all of them was the same. This made him think that the knees did not really do much of the work. To investigate further, he examined the insect's legs under a sophisticated electron microscope and observed that while the shin and toe had gripping claws, the knee or tronchater was completely smooth, which led him to believe that there was no way the insect could do its huge jumps using just the knees.
As a final test, he invited Cambridge engineer, Dr. Gregory Sutton, to do some mathematical models to test if his theory was correct. Dr. Sutton concurred, saying there was no way the insect could jump using just the legs, especially given how small they are. Instead, what they do is grip the ground with their toes, and use it as lever system for their legs to take off with this huge amount of force - Proving that Dr. Bennett had been right all along!
So why is this important? The Cambridge scientists believe that we can use similar techniques to build robots to leap through rough terrain.
However, before we do that there are a few mysteries that Dr. Clark still needs solve - like how fleas lock their springs in place and release them and also how they control the movement of their rear hindmost legs so precisely, so that they take off at the same time - For if they didn't they would be flying out of control! Who know that there was so much to learn from the tiny flea? Science is truly quite fascinating, isn't it?
Resources: Telegraph.co.uk, msnbc.msn.com, dailymail.co.uk, nytimes.com