Juvenile bigclaw snapping shrimp can clamp their claws nearly twenty times faster than their parents. The acceleration is similar to a bullet leaving a gun and even faster than mantis shrimp
28 February 2023
Juvenile snapping shrimp have broken the acceleration record for a repeatable body movement underwater. The tiny crustaceans can snap their claws with an acceleration of nearly 600,000 metres per second squared – similar to that of a bullet leaving the barrel of a gun.
The record cleanly beats adult snapping shrimp, and even other famously zippy underwater species such as mantis shrimp, which use their ultrafast claws to punch enemies or bash up prey.
Bigclaw snapping shrimp (Alpheus heterochaelis), which grow to several centimeters long, have spring-like mechanisms on the larger of their two claws. When this mechanism is released, it whips the claw closed, creating a high-speed water jet and a loud popping sound that startles potential predators. Previous studies have found that adult shrimp reach claw-snapping accelerations of around 30,000 m/s2.
Jacob Harrison and Sheila Patek at Duke University in North Carolina wanted to see how juveniles, which are only a few millimeters long, compared. They raised some in the lab, and then used a camera attached to a microscope to take videos of one- and two-month-olds snapping their claws.
When they tried filming at 50,000 frames per second – the frame rate they’d use for adult shrimp – the claw’s movement was still just a blur, says Harrison. “It was like, ‘Wow, these guys are really cooking.’” It wasn’t until the researchers upped the camera speed to 300,000 frames per second that they could measure just how fast the animals were moving their limbs.
It turned out that young shrimp were accelerating their claws at 580,000 m/s2. That is around 20 times faster than their parents. “These are insanely high accelerations,” says Harrison.
The whole snap takes just 300 microseconds – a blink of an eye lasts around 500 times that. Very few creatures can beat this kind of speediness. One exception is the Dracula ant, which can shut its jaws in just 23 microseconds. But it’s easier to move quickly in air than it is in water, meaning shrimp have to work harder to reach the same speeds.
There is technically one animal that can pack a higher acceleration in the underwater world, although it breaks its spring mechanism in the process. Jellyfish shoot little harpoons into objects that brush their surfaces, and these barbs can reach accelerations nearly a hundred times higher than that of the shrimp’s claw. But each harpoon is a one-off, as it remains stuck in the victim after being shot.
The comparisons make the shrimp’s achievement that much more impressive, says Harrison, adding that the crustacean’s ultrafast limbs may help researchers design jumping robots and other devices relying on spring mechanisms. “These snapping shrimp have these crazy high accelerations,” he says, “but they can do it in water, and they’re doing it repeatedly.”
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