Having hairy legs may make shrimp better swimmers.
“Can hair help you swim better? The swimmer will say no, but the shrimp will say yes,” Sara Oliveira Santos of Brown University in Rhode Island said at a fluid dynamics conference this week. He and his colleagues studied how shrimp and shrimp-inspired robots swim to determine whether it was beneficial for them to be hairy.
Shrimp use a special swimming technique called metachronal swimming to move easily in water. They beat their swimming appendages, called swimrats, in exactly the right order to create a wave that travels from their tail to their head and the drag force propels them forward rather than slowing them down.
For human swimmers, hairiness makes swimming difficult because it increases drag, but many shrimp swimmers are covered with thin hair-like structures called setae and even smaller setulae. To determine whether this hairiness makes metachronal swimming easier, the researchers first attached a leg of a dissected shrimp to a mechanical joint, immersed it in water and filmed how it moved with the jet of dyed fluid. Conversates. Their recordings showed that under certain conditions, very little liquid penetrates through the hair-like structures and the appendage moves like an efficient oar.
They also built several large-scale robotic swimming appendages, some with multiple artificial setae and setae and some without any. The researchers moved these through a fluid filled with tiny particles that glow when illuminated. Recordings from these experiments revealed how vortices form and rotate around each robotic appendage.
Based on analysis of this whirling motion, the team concluded that hairy appendages experienced less stress on their joints than completely smooth appendages, meaning that having hair may have made it easier for the animals to swim. .
Oliveira Santos presented the work at the American Physical Society Division of Fluid Dynamics meeting in Washington, DC, on November 19.
Now, the team is working on measuring more quantitatively the size of the benefit of the shrimp’s hairy appendages, such as how much it increases their speed.
- fluid dynamics,
- Marine Life