Flightless animals have evolved a wondrous diversity of ways to control their movements up in the air. Cats rotate their body when falling, some lizards use their tail to change direction mid-air, and when wingless mantises jump, they use controlled spinning motions to reorient their bodies as needed. That’s how they land on their target each and every time, according to a study published in Current Biology this week.
Many jumping insects, from fleas to grasshoppers, lose all control once their legs leave the ground -- spinning unpredictably and then crash landing. Yet young, wingless praying mantises are not only precise jumpers, they're quick too: The amount of time from take-off to landing is less than a tenth of a second. Blink and you’ll literally miss it. Watch this slow-motion video of an impressive jump.
To figure out how baby insects accomplish these aerial acrobatics, Cambridge’s Malcolm Burrows and colleagues watched 381 high-speed videos of 58 young Stagmomantis theophila mantises jumping from a platform to a thin black stick a couple body lengths away. They used to think that these insects had evolved a way to deal with the spin that naturally occurs when small animals jump at those speeds. Well not so! The mantis deliberately injects controlled spin into the jump, rotating its body parts in a specific sequence to reposition itself mid-air and grasp the target precisely.
"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," Burrows says in a news release.
Here’s the order of the tightly controlled events: To prepare for a jump, the insect sways its head sideways and scans for targets before rocking its body backward and curling its abdomen up and out. Then, with a push from the legs, the mantis hurls into the air and spins its body: Its abdomen, front legs, hind legs rotate independently, shifting from clockwise to anti-clockwise mid-air. By transferring the spin (or angular momentum) from one body part to the next, the mantis keeps its body as a whole aligned with the target. And all this happens in 80 milliseconds.
"We had assumed spin was bad, but we were wrong -- juvenile mantises deliberately create spin and harness it in mid-air to rotate their bodies to land on a target," Burrows says in a university statement. "As far as we can tell, these insects are controlling every step of the jump. There is no uncontrolled step followed by compensation.”
When they moved the target closer, the mantises spun themselves twice as fast to make sure they were parallel to the target when they grab on. Then the team tried restricting the ability of the mantis to manipulate and spread angular momentum to its extremities. When they glued the segments of the abdomen together, the mantises still reached the target -- but because they couldn't rotate their bodies into the correct position, they crashed. Here’s a video of a mantis wipeout captured at 1,000 frames per second:
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