February 10, 2011

High-Speed Camera Sheds Light On Agility Of Fleas

Researchers from Cambridge University have successfully recorded fleas jumping, and in the process discovered exactly how the tiny insects leap so quickly and cover such great distances.

While Henry Bennet-Clark discovered in 1967 that fleas are capable of storing enough energy to catapult themselves high into the air and cover distances some 200 times their own body length, questions remained about exactly how the creatures were able to utilize that stored energy.

According to a press release, Cambridge researchers Malcolm Burrows and Gregory Sutton noticed an infestation of hedgehog fleas near their laboratory sometime last year, and decided to see if they could answer the questions once and for all using a high-speed camera.

"We were concerned about how difficult it would be to make the movies because we are used to filming locusts, which are much bigger than fleas," Sutton said in a statement, adding that he and his colleague eventually realized that fleas would only jump in the light and would remain perfectly still in darkness.

Using that knowledge, they were able to record 51 jumps from 10 different fleas, and discovered that they tended to push off with their tarsus (or toes) rather than their trochanters (or knees).

In fact, in 10% of the jumps recorded, the trochanters did not even touch the ground and thus was not used by the fleas to gain height, distance, or velocity whatsoever, leading Burrows and Sutton to ponder whether or not they were even necessary at all.

"If you look at the actions and movements animals can generate, they are so much better than modern machines," Sutton told BBC News Science and Technology Reporter Victoria Gill on Thursday. "So I was interested in studying exactly how they generate these movements."

However, he and Burrows told Gill that more research is required to fully unlock the mystery of the flea's amazing agility.

"They always jump in the same direction and so we think they may be limited," he told BBC News. "And we don't know how the flea locks its legs into position when it's charging the spring"¦ This just shows us how little we know about [the abilities of] very common insects."


Image 2: This image shows the anatomy of a flea showing sections of the leg. Credit: Gregory Sutton


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