Artificial Whiskers from a Harbor Seal Can Sense the Environment and Track
Harbor seals have the uncanny ability to sense prey using their whiskers. Now, scientists have fabricated and a large-scale model of a harbor seal's whisker, and identified a mechanism that may explain how seal sense their environment and track their prey.
In their experiments, the researchers observed that once the fabricated whisker enters the wake left by a passing object, it starts vibrating at the same frequency as the wake's passing vortices. Careful visualizations show that the whisker "slaloms" among the vortices, rather like a skier zigzagging between flags.
In fact, this slaloming allows the whisker to extract energy from the wake, causing it to vibrate at the precise frequency of the wake-a mechanism that may give seals a clue to an object's path, its size and even its shape.
What's interesting is that a seal's whiskers are unique in shape. Even to the naked eye, you can see that individual whiskers aren't uniform, but are instead wavy. Under a magnifying glass, the pattern is even more intricate.
"It's marvelous to see this intricate pattern, it's not just a straight antenna-it's a perfect sinusoid," said Michael Triantafyllou, one of the researchers, in a news release.
The researchers actually tested the whisker's vibration properties in a 30-meter-long tank of water with a moving track suspended above the water. In her experiments, the researchers attached the artificial whisker to a moving track, allowing the whisker to vibrate freely in the water as it moved down the length of the tank.
"We already have a few sensors that can detect velocity, but now that we know better what they can do, we can use them to track sources of pollution and the like," said Triantafyllou. "By having several whiskers on a vehicle; like the seal, you can, for example, detect a faraway plume, and track it all the way to the end."
These new findings about the whisker could be huge when it comes to creating underwater vehicles and other navigation systems.
The findings are published in the Journal of Fluid Mechanics.
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