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 (200 times their own body weight), 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 known that, but have also pondered and debated about it, for the last 44 years.
The main area of contention was not the tiny insect's ability to generate energy that is 100 times what its muscles 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 froghoppers, fleas store their energy inside a stretchy protein pad called resilin, which is connected to the legs. The thing researchers could not agree upon was how it channeled the stored energy into the 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 leaped using their knee-like structures or tronchaters.
Now thanks to Dr. Malcolm Burrows and Dr. Gregory Sutton from University of Cambridge, this age-old debate has finally been put to rest. The researchers who published their findings in the Journal of Experimental Biology on February 10th, began by using high-speed recording equipment to film 51 jumps performed by 10 hedgehog fleas.
What they noticed was that for most jumps, both the toes (tarsi) and knees (tronchaters) came in contact with the ground prior to take off. However, for about 10 percent, the insects used just the toes. What was even more interesting was that regardless of how the jump was conducted, the height and rate of acceleration remained constant. This led the researchers to speculate that the knees were not that important to the jumping process.
To investigate further, they 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, confirming their initial suspicion that the knees had little to do with the large leaps.
As a final test, Dr. Gregory Sutton, ran some mathematical models to verify if the theory was correct. Sure enough, the models indicated that the insect's legs are too small to sustain the jumps. Instead what they do to leap to the extraordinary heights, is grip the ground with their toes and use them as levers for their legs. This allows them to take off with the huge amounts of force they are so well-known for. Turns out, Dr. Bennett had been right all along!
So why is this important? The Cambridge scientists believe that we can mimic the flea's technique to build robots that can leap through rough terrain. However before that happens, there are a few other mysteries that still need to solved - like how fleas lock their springs in place and release them and also how they are able control the movement of their rear hindmost legs such that they take off at the same time - a technique that allows them to land perfectly on their target! Who knew there was so much to learn from the tiny flea?
Resources: Telegraph.co.uk, msnbc.msn.com, dailymail.co.uk, nytimes.com