A recent study has shown that seal whiskers are effective in tracking and hunting prey, making them excellent hunters. The findings, published in the journal Smart Materials and Structures, resulted from work conducted by a team of experts at the Massachusetts Institute of Technology.
Previous experiments by marine biologists had shown that harbor seals possess an uncanny ability of detecting prey. For example, even swimming blindfolded, trained seals could successfully identify the trajectory of an object that went past them 30 seconds earlier.
There, it had been speculated that whiskers hold the key to this effectiveness in tracking prey, by functioning just like antennae. In order to test the inner mechanism of these whiskers, researchers employed 3-D printing techniques in order to created over-sized, artificial copies of them.
Afterwards, they carried out an experiment in order to see how the morphology of these hairs contributes to the mammals’ unusual sensitivity when it comes to acknowledging motion. The whiskers were used in a 30-meter long aquarium, by attaching them to a moving track.
The experts discovered that the shape of these bristles actually helps limit their own vibration and movement as the mammal swims, having thus the effect of making the seal’s presence less obvious to its quarry.
On the other hand, when using a large cylinder as a potential prey, researchers discovered that the whiskers began to vibrate and sway in a “slaloming”, zigzag motion as the object moved nearby, disrupting the waters. In fact the bristles’ oscillations were identical in frequency of the turbulence left the quarry.
As scientists explain, thanks to these vortices, seals can estimate how large the prey is, what shape it might be and what path it is on. Based on these assessments, the marine mammal can then decide whether to commence a pursuit or not.
The shape of the whiskers has actually left scientists fascinated since its elliptical cross-sections are perfectly built to allow seals to determine external vibrations, without actually having to see the prey or notice its actual movements.
“It’s marvelous to see this intricate pattern, it’s not just a straight antenna – it’s a perfect sinusoid”, explained study lead author Michael Triantafyllou, mechanical engineer at Massachusetts Institute of Technology.
It seems that very few species of seal have this type of type of twirling whiskers. By comparison, sea lions and walruses actually have straight whiskers instead.
Previous research had hinted that whiskers might provide mammals with extra ability to identify stimuli in the environment. Now, thanks to this study, it has been proven that these distinctive features also play an active role in the hunting rituals of some species.
Also, as the lead author suggests, the findings might be beneficial in designing low-power sensors mirroring harbor seal whiskers. These could be used for detecting schools of fish, as well as for identifying sources of water pollution.
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