Though many mammalian species use their adorable whiskers to gather sensory information about the world around them, seal whiskers are something special. The number of nerve endings in these specialized hair follicles varies from species to species, and while animals like cats and rats have around 200 nerve endings in each whisker, seals sport an amazing 1,500. Their whiskers convey so much sensory information that, deprived of sight and hearing, the aquatic mammals can still accurately pinpoint the locations of fish in the water around them.
According to The Atlantic, scientists are amazed by the unique abilities of seal whiskers—and they’ve developed a series of eccentric studies over the course of the last decade to learn more about them. They’ve blindfolded seals and watched them continue to navigate with ease; put noise-canceling headphones on them and observed them catching prey. “Rather than rely on sight and sound,” The Atlantic explains, “The seals use antenna-like whiskers—precise instruments of marine carnage capable of sizing up a herring down to the centimeter.”
In a recent study, a group of scientists at Massachusetts Institute of Technology even 3D printed an oversized seal whisker to learn more about how their strange shape affects sensory perception. While most mammalian whiskers are circular, and grow thinner as they stretch away from an animal's face, seal whiskers are elliptical and their thickness fluctuates. This has a serious impact on the way seal whiskers move through water—and the way seals pick up information about their environment.
Dragging the oversized whisker through a tank of water, the researchers found that it created minimal disturbance: its elliptical shape allowed it to flow easily through the water, without stirring up turbulence. But when the scientists dragged a circular rod through the water ahead of the whisker, it created vibrations, which the whisker in turn picked up. This means that, even when seals are in motion, their whiskers remain relatively still, vibrating only in response to the movement of other animals or objects in the water.
“Now we have an idea of how it's possible that seals can find fish that they can't see,” researcher Heather Beem explained. “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.”
Scientists ultimately hope to harness the power of seal whiskers for future underwater technologies: “The geometry prevents these whiskers from causing vibrations, which is an advantage that can be exploited with other sensors. It is important for some sensors to not generate noise,” researcher Michael Triantafyllou told The Atlantic.
[h/t: The Atlantic]