Navigation Links
44-year-old mystery of how fleas jump resolved

If you thought that we know everything about how the flea jumps, think again. In 1967, Henry Bennet-Clark discovered that fleas store the energy needed to catapult themselves into the air in an elastic pad made of resilin. However, in the intervening years debate raged about exactly how fleas harness this explosive energy. Bennet-Clark and Miriam Rothschild came up with competing hypotheses, but neither had access to the high speed recording equipment that could resolve the problem. Turn the clock forward to Malcolm Burrows' Cambridge lab in 2010. 'We were always very puzzled by this debate because we'd read the papers and both Henry and Miriam put a lot of evidence for their hypotheses in place and their data were consistent with each other but we couldn't understand why the debate hadn't been settled,' says Burrows' postdoc, Gregory Sutton. He adds, 'We had a serendipitous set of hedgehog fleas show up so we figured we'd take a crack at it and try to answer the question'. Filming leaping fleas with a high-speed camera, Sutton and Burrows found that fleas push off with their toes (tarsus) and publish their discovery in The Journal of Experimental Biology at

'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,' admits Sutton, but he and Burrows realised that the fleas stayed perfectly still in the dark and only jumped when the lights went on. Focusing the camera on the stationary insects in low light, the duo successfully filmed 51 jumps from 10 animals; and this was when they got their first clue as to how the insects jump.

In the majority of the jumps, two parts of the flea's complicated leg the tarsus (toe) and trochanter (knee) were in contact with the ground for the push off, but in 10% of the jumps, only the tarsus (toe) touched the ground. Sutton explains that Rothschild had suggested that fleas push off with the trochanter (knee), but if 10% of the jumps didn't use the trochanter (knee) was it really necessary, or were the fleas using two mechanisms to get airborne?

Burrows and Sutton needed more evidence. Analysing the movies, the duo could see that the insects continued accelerating during take-off, even when the trochanter (knee) was no longer pushing down. And the insects that jumped without using the trochanter (knee) accelerated in exactly the same way as the insects that jumped using the trochanter (knee) and tarsus (toe). Also, when Burrows and Sutton looked at the flea's leg with scanning electron microscopy, the tibia (shin) and tarsus (toe) were equipped with gripping claws, but the trochanter (knee) was completely smooth, so it couldn't get a good grip to push off. Sutton and Burrows suspected that the insects push down through the tibia (shin) onto the tarsus (toe), as Bennet-Clark had suggested, but the team needed one more line of evidence to clinch the argument: a mathematical model that could reproduce the flea's trajectory.

'I looked at the simplest way to represent both models,' explains Sutton. Building Rothschild's model as a simple mass attached to a spring pushing down through the trochanter (knee) and Bennet-Clark's model as a spring transmitting the spring's force through a system of levers pushing on the tarsus (toe), Sutton generated the equations that could be used to calculate the insect's trajectory. Then he compared the results from his calculations with the movies to see how well they agreed.

Both models correctly predicted the insect's take-off velocity at 1.35m/s, but then the Rothschild model began to go wrong. It predicted that the insect's acceleration peaked at a colossal 22,000m/s2 (2200g), whereas the acceleration of the insects in the movies only peaked at 1500m/s2 (150g). However, Sutton's calculations based on the Bennet-Clark lever model worked perfectly, accurately predicting the insect's trajectory and acceleration pattern.

So Sutton and Burrows have finally settled the argument and resolved how fleas jump. The insects transmit the force from the spring in the thorax through leg segments acting as levers to push down on the tarsus (toe) and launch the 0.7mg animals at speeds as high as 1.9m/s.


Contact: Kathryn Knight
The Company of Biologists

Related biology news :

1. Biologists discover gene behind plant sex mystery
2. Yale researchers unravel mystery of brain aneurysms
3. Deep heat solution to 500-million year mystery
4. Researchers solve piece of large-scale gene silencing mystery
5. MIT researchers explain mystery of gravity fingers
6. Peering inside the skull of a mouse to solve meningitis mystery
7. Fish guts explain marine carbon cycle mystery
8. Fishdunnit! Mystery solved
9. Biologists solve mystery of black wolves
10. Life secret exposed: Scientists unlock mystery of molecular machine
11. Genetic sleuth solves glaucoma mystery
Post Your Comments:
Related Image:
44-year-old mystery of how fleas jump resolved
(Date:10/27/2015)... 27, 2015 In the present market scenario, ... for various industry verticals such as banking, healthcare, defense, ... growing demand for secure & simplified access control and ... as hacking of bank accounts, misuse of users, , ... as PC,s, laptops, and smartphones are expected to provide ...
(Date:10/27/2015)... SAN JOSE, Calif. , Oct. 27, 2015 /PRNewswire/ ... human interface solutions, today announced that Google has adopted ... family of touch controller solutions to power its newest ... Nexus 6P by Huawei. --> ... ecosystem partners like Google to provide strategic collaboration in ...
(Date:10/26/2015)... and LAS VEGAS , Oct. ... Labs , an innovator in modern authentication and a ... announced the launch of its latest version of the ... enabling organizations to use standards-based authentication that supports existing ... S3 Authentication Suite is ideal for organizations deploying customer-facing ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... Studies reveal the differences in species of ... way for more effective treatment for one of the most ... --> --> Gum disease is ... yet relatively little was understood about the bacteria associated with ... by researchers from the WALTHAM Centre for Pet Nutrition together ...
(Date:11/25/2015)... 2015 /PRNewswire/ - Aeterna Zentaris Inc. (NASDAQ:  AEZS; TSX: ... prospects remain fundamentally strong and highlights the following ... received DSMB recommendation to continue the ZoptEC Phase ... the final interim efficacy and safety data ... men with heavily pretreated castration- and Taxane-resistant prostate ...
(Date:11/25/2015)... November 25, 2015 The ... is a professional and in-depth study on the ...      (Logo: ) , ... industry including definitions, classifications, applications and industry chain ... the international markets including development trends, competitive landscape ...
(Date:11/24/2015)... ... November 24, 2015 , ... The United States Golf Association (USGA) today ... Green Section Award. Presented annually since 1961, the USGA Green Section Award recognizes an ... turfgrass. , Clarke, of Iselin, N.J., is an extension specialist of turfgrass ...
Breaking Biology Technology: