Harbor Seals Use a Sixth Sense to Track Their Prey

Not only are harbor seal whiskers incredibly cute, they are also incredibly useful. Engineers at MIT have discovered that the whiskers help the seal to be an extremely effective hunter.

To the naked eye, the whiskers have a unique wavy shape. But under a magnifying glass, a more intricate elliptical pattern appears. These wavy whiskers respond to the seal’s own movements by remaining still. However, when the water is disturbed by something like a passing fish, the whiskers unique shape respond with oscillating movements. These oscillations give the seal clues into the size, shape, and path of the fish, even if it had passed by 30 seconds earlier.

“The geometry of the whisker allows for this phenomenon of being able to move very silently through the water if the water’s calm, and extract energy from the fish’s wake in order to vibrate a lot. Now we have an idea of how it’s possible that seals can find fish that they can’t see.”

factorialist_sealwhiskerscloseup 

Researchers created large 3D replicas of the whiskers in order to accurately test the way they responded to movements in water. What they discovered is that the whisker shape created weaker vortices with very little vibration when moving through the water. However, when they added a stimulus that mimicked the pattern of a swimming fish, the whiskers started to move in a slaloming motion. If the pattern was sped up or slowed down, the whiskers quickly adjusted to match the new pattern. The slaloming allows the whiskers to match the frequency of the wake, helping the seal to track its prey.

SourceScience Daily
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ImagePLOS.org

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