Seals’ whiskers provide a model for the latest submarine detectors
VISION is useless in murky water. To deal with that deficiency dolphins have evolved sonar. They emit clicks and interpret the echoes to find their prey. But not all marine mammals are so equipped. Seals, for instance, have no sonar, yet that does not stop them finding distant meals as effectively as dolphins can. This puzzled researchers for years, until they discovered that the secret lies in the animals’ whiskers—which they are now trying to copy, to develop novel underwater sensors.
An object moving through water leaves a series of miniature whirlpools in its wake. This trail is called a Karman vortex street. And that is what seals, using their whiskers, follow. As Michael Triantafyllou of the Massachusetts Institute of Technology (MIT) observes, “You can set a harbour seal loose to follow a towed fish, and even 30 seconds later they will be able to follow the exact track, whether it’s straight or zigzag or circular.”
Dr Triantafyllou and his colleagues at MIT’s Centre for...