Wavy Whiskers Make Seals Incredible Hunters

They may look cute and cuddly, but seals are some incredibly ferocious and impressive hunters, gliding silently through the water only to snap their sharp teeth around an unsuspecting fish. More amazing still, even in the low visibility of murky water, they can hunt their food with frightening precision. How do they do it? Wavy facial hair, it turns out, can be a predators' secret weapon.

That's at least according to findings recently released ahead of print through the Cornell University Library. In their paper, researchers Heather Been and Michael Triantafyllou detail how quick movements through water cause shifts called "vortex wakes," which in turn can be picked up by seal whiskers. Amazingly, these movements can be detected up to 30 seconds of swimming away from a seal, giving the sleek hunter just that long to catch up to its prey.

However, it remained a mystery as to how seal whiskers remained so impressively sensitive even while the animal is swimming. After all, standard whisker hairs, like those seen on cats, boast a simple cylindrical shape that tapers down to a point. This shape causes them to be buffered in moving wind or water - a consequence that would make sensitivity to vortex wakes impossible.

Seal whiskers, however, are not uniformly cylindrical, and instead widen and thin over and over, creating a "wavy" pattern. (Scroll to read on...)

To analyze whisker mechanics on a swimming seal, the researchers made a model hair and dragged it through a tank of water.

The whisker's curvy shape - with an ellipse-shaped cross section - barely wiggles, suggesting that movement in the water actually stabilizes these feelers. In fact, they likely remain completely still at top speeds, serving almost as a fourth sense near the end of a chase.

interestingly, sharks boast a similar mechanism to help them hone in on prey at the last moment, although it is far more invisible than a face full of wavy whiskers. A consequence, however, is that sharks are now mistaking cable lines for prey. You can learn more about that research here.

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