These juvenile snapping shrimp have the fastest claws in the sea

Snapping shrimp, also known as pistol shrimp, are one of the loudest creatures in the ocean. Also, according to a recent paper published in the Journal of Experimental Biology, young snapping shrimp are even faster than full-grown older shrimp. Accelerates as fast as the , essentially setting a new acceleration record for repeated movements in water.

As previously reported, the cause of that large snap is an impressive set of asymmetrically sized claws. The larger of the two will generate the snap. Each snap also creates a powerful shockwave that stuns or kills small fish. Its shockwave creates a collapsing bubble, emitting an almost invisible flash of light. This is a rare natural example of sonoluminescence.

Scientists believe snaps are used for communication and hunting. Prowling shrimp hide in burrows or similar obscure places and extend their antennae to detect passing fish. The shrimp then emerges from its hiding place, pulls back its claws, and releases with a powerful snap, creating a deadly shockwave. The stunned prey can then be pulled back into the burrow and fed.

In 2020, scientists at the Woods Hole Oceanographic Institution published the results of an experiment using pistol shrimp. They concluded that as ocean temperatures rise with climate change, shrimp snaps will become more frequent and louder than before. Body temperature and activity levels respond to changes in the environment. This will make the world’s ocean soundscapes even louder. As to why shrimp seem immune to their own powerful snaps, the scientist said in 2022 that shrimp are protected by tiny transparent helmets that prevent serious nerve damage by dampening shock waves. concluded.

This latest study focuses on shrimp snapping large claws alpheus heterochelys, Native to the western Atlantic, especially the Gulf of Mexico. Co-authors Jacob Harrison and Duke University’s Sheila Patek were interested in evolutionary biomechanics and wanted to learn more about the so-called “latch-mediated spring actuation” (LaMSA). Equivalent to tuned springs and latches to store and release elastic energy. (This is also how legless larvae fly through the air, and how certain plants shoot their seeds like ballistic missiles.)

They were particularly interested in identifying at what size and age snap shrimp develop the elements behind the LaMSA mechanism, and how juvenile snap shrimp kinematics compare to adult snap shrimp. They collected eggs from female snap shrimp in Beaufort, South Carolina, and carefully scraped the eggs from myriapods that were stored during development. The eggs were placed in a small plastic container filled with synthetic seawater, mounted on a shaker table, and rocked gently to keep the water flowing over the eggs.

All eggs hatched within 20 days and larvae were cared for and monitored until they reached the postlarval stage. At that point, they were transferred to individual plastic containers and fed with brine shrimp eggs. Harrison and Patek selected 20 snapping shrimp from each of his four egg clutches for further study.

The researchers then induced a strike and captured high-speed video of the action with a microscope-mounted camera, yielding 125 complete strikes suitable for tracking strike kinematics. Initially, they shot at 50,000 frames per second (fps). However, the juvenile claws were moving too fast, so he switched to 300,000 fps to capture the movement.

Harrison and Patek found that even on a millimeter-sized scale, young snapping shrimp can snap their claws fast enough to generate cavitation, and those with larger claws tend to snap longer than smaller clawed shrimp. We have found that we can generate cavitation bubbles that are persistent and travel far.², 20 times faster than the claw acceleration of adult snapping shrimp. A full snap was completed in just 300 microseconds.

The authors also compared larval attack acceleration with that measured in previous studies of mantis shrimp larvae, trap-jaw spiders, slingshot spiders, bark beetle larvae, trap-jaw ants, and ~77 frog species. . Lamb ants can match the impressive acceleration of juvenile snap shrimp, and Dracula ants and termites show even higher accelerations. However, all three species are active in the air rather than in the water and therefore do not compete with hydrodynamic drag.

In fact, according to a 2006 study, the only known similarly sized creatures with faster acceleration in water are jellyfish. Specifically, nematocysts in jellyfish tentacles retain barbed or poisonous coiled threads that can be released for self-defense or to capture prey. But the authors point out that like harpoons, these nematocysts are only fired once and remain on the target: “These snapping shrimp have very high acceleration,” Harrison said. he told New Scientist.

DOI: Journal of Experimental Biology, 2023. 10.1242/jeb.244645 (About DOI).

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