How does this Teeny-Tiny sea crack like Mike Tyson collapse

Less than a quarter of a centimeter long, the amphipod – a crustacean that looks a bit like shrimp – lives a leisurely life, passing through algae up and down the East Coast. Well it is superficial leisurely, as scientists have just discovered. A male amphipod has a massive claw that can exceed a third of its mass, and when it fixes it in less than 10,000 seconds, it organizes an overloaded jet of water to make its dissatisfaction known. Thanks to a $ 150,000 camera filming at 300,000 frames per second, researchers captured for the first time a male amphipod in action, a moment so violent that it is almost enough to the animal explodes.

You’re probably wondering how to experimentally upset a male amphipod – more specifically, the species Dulichiella cf. appendiculata. So I tell you. Working in the laboratory, the researchers glued toothpicks to the animals’ backs, then attached the toothpicks to “micromanipulators”, devices that allowed them to accurately position the amphipods. All they had to do was hang their hair from a brush near the amphipods, violating their personal space. And then, SNAP. “So I use it clearly in an aggressive context,” says Sheila Patek, a Duke University biologist and co-author.

With the running of the ultra-fast camera, Patek and her colleagues suddenly made the invisible visible. “In a way, it’s almost magical,” says Patek. Previously, you might only hear or feel an amphipod if you had one in a tray, not if you looked at one in the wild. “But then, to highlight everything and beautiful lighting, you can suddenly see this little appendix filling the screen, loading it and then breaking it,” she says.

The critical part of this appendix, more formally known as a gnatopod, is called the dactyl. In the image above, this is the long, blade-like structure at the top of the claw. It is no thicker than human hair. To break, the amphipod contracts a muscle, throwing back that dactyl and storing an incredible amount of energy. Patek and her colleagues need to do more work to fully understand the morphology of how the snap works, but it is likely that a latch will hold the finger in place. When the animal is ready to catch, it releases the latch, suddenly releasing the stored energy of the claws.

“And then, when we look further, we say to ourselves, ‘Wait, there’s a water jet getting out of there! ” Says Patek. Specifically, the force of the claw clip seems to push the water at an oblique angle, rather than perfectly straight forward. “And then, God, from time to time, the jet of water seems to provoke cavitation, which is the formation of these vapor bubbles, which happens when you flow at these extraordinary speeds. “When these little cavitation bubbles collapse, they do explode, unleashing an explosion of energy. This type of force is so strong, in fact, that when boat propellers create their own cavitation bubbles, over time the force chews the metal of the blade.