By Tess Joosse
How many times can you snap your fingers in a second? Whatever your record, you can not see the essence in the video above. This ‘amphipod’ – a microscopic, shrimp crustacean – claps its claws thousands of times per second. According to a new study, it is one of the fastest repeatable movements in the animal kingdom, and one that practically contradicts the laws of physics.
Amphipod (Dulichiella vgl. appended) feed on dead algae and seaweed in the cool coastal waters they call home. Men have a single asymmetrical claw that makes up about one-third of their total body mass. This attachment consists of a thumb-like ‘propodus’ and a hinged ‘dactyl’ that can open and close quickly and easily, although it is just as wide as a human hair.
In the new study, scientists placed male amphipods under a speed camera that enabled them to place each snap in the frame precisely. The fastest movements occurred in less than 50 microseconds, or 100,000 times shorter than a blink of an eye, the researchers reported today in Current biology. The speed is particularly remarkable, the team says, because the water flow has to slow down the snaps.
The scientists also found that the claws make audible bouncing noises and generate water jets with each slap. Some of the rays were so intense that they generate a powerful phenomenon called cavitation, when rapid pressure changes create bubbles in the water. In the delayed video above, you can see an elongated bubble shoot out of its claw every time it strikes.
The researchers then want to investigate why such a small animal has to move so fast. One thought is that the amphipod moves its claws as communication during territorial or mating disputes. Their message? Click from it.