Young snapping shrimp are the sea's most powerful claw

Young snapping shrimp are the sea's most powerful claw ...

Snapping shrimp were already known to have some of the finest claws under the waves. However, they aren't as powerful as their children.

Researchers report the most remarkable underwater accelerations of any reusable body part on February 28 in the Journal of Experimental Biology. Although the peak speed isn't particularly impressive, the claws go from zero to full throttle in record time.

Snapping shrimp send shock waves out of their powerful claws, much like a bow-and-arrow mechanism.

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A swifting jet of water is produced when the claw is slashed, and bubbles form behind it, releasing a significant amount of energy, momentarily flashing as hot as the sun, and causing a deafening crack (SN: 10/3/01).

'We knew that the snapping shrimp was a fantastic performer,' Harrison adds. 'We didn't know anything about how this mechanism worked.'

Harrison and his adviser, biomechanist Sheila Patek, raised bigclaw snapping shrimp (Alpheus heterochaelis) from eggs in the laboratory at the age of 1 month old. They captured high-speed video footage of these snaps and calculated their speed.

The wee shrimp might sabotage the collapsing bubbles like adults. The juveniles' claws accelerated 20 times as fast when firing, according to Harrison. This speed is "on the same order of magnitude as a 9-millimeter bullet leaving a gun."

The stinging cells of jellyfish launch their venomous harpoons about 100 times as fast, but snapping shrimp can fire their claws again and again.

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At the smallest sizes, the juveniles' firing and bubble creation weren't very reliable, but the shrimp tended to snapping anyway, so the group is curious if the young shrimp are practicing and training the necessary muscles.

Kate Feller, a visual ecologist at Union College in Schenectady, New York, specializes on ultrafast mantis shrimp but was not involved in the new study. "If you could manipulate the claws so that they couldn't close properly and they wouldn't snap," she says, "would that affect their ability to develop these mechanisms?"

Harrison finds it difficult to comprehend how elastic energy is stored in biological materials and how it flows through them. Understanding how tiny claws store so much energy without fracturing might help scientists understand this superpower.

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