Praying mantis looks long before it leaps

[March 06, 2015]  Slowed-down video footage of a series of praying mantises leaping towards a target has demonstrated the extraordinary precision of the insect while jumping.

British scientists Malcolm Burrows and Gregory Sutton studied the insect's jump, which from take-off to landing lasts less than a tenth of a second - faster than the blink of a human eye. During a jump, the insect's body rotates in mid-air at a rate of about 2.5 times per second.

Burrows and Sutton, from the universities of Cambridge and Bristol respectively, recorded 58 young mantises jumping towards a thin black rod. They recorded almost 400 of the leaps, before slowing down the footage.

Monitoring the videos, the researchers saw that in preparation for a jump, the insects sway their heads sideways, scanning for their targets, before rocking their bodies backwards and curling their abdomens upwards, with the tip pointed forward.

After pushing into the air with their legs, the mantises' bodies launched into the air, spinning in controlled fashion. The insects each rotated their abdomen, front and hind legs, independently and in a complex sequence. As the mantises sailed through the air, the spin was transferred from one body segment to the next, keeping the body as a whole level and directly on target.

"Maintaining stability so that the body does not rotate uncontrollably in mid-air is a difficult task," said Burrows. "When the movement is rapid, as it is in a jump, and you don't have wings, then the task is even more difficult. Nevertheless, a praying mantis moves rapidly and controls the rotation of its body so that it lines up precisely with a target, and does all of this in less than 100 milliseconds."

Such jumping control is unusual in the insect world. Most insects lose all control once their legs leave the ground, the researchers say, spinning in unpredictable directions with frequent crash landings.

According to Burrows, the mantises' jumps are precise, landing on target every time. "This is akin to asking an ice skater who is rotating at the same speed as these mantises to stop suddenly and accurately to face a specific direction," he said.

The young mantises' skill could be used to help develop small leaping robots.

The researchers report their observations in the Cell Press journal Current Biology on March 5.

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