Blindfolded and fitted with noise-canceling headphones, this seal might better fit a marine-creature hostage crisis than a scientific study. In reality, it’s making history by showing for the first time that the whiskers of harbor seals are so sensitive that they can discern the shapes of objects by the ripples they make. Marine biologists have known for a while that seals use their whiskers to find fish in dark, murky waters, but as lead researcher Wolf Hanke told LiveScience, whiskers had “never been shown to analyze things” beyond that. Being able to discern shape and size means that seals may use their whiskers to pick out the fattest fish.

Henry, a 12-year-old harbor seal, was plopped into an open-air pool in a Cologne zoo to put his whiskers to the test. Researchers blindfolded and placed headphones on him so that he could only use his whiskers to sense underwater objects. In the pool, the researchers placed a plastic box containing an assortment of variably-shaped paddles. Because they trained Henry to touch his nose to a small plastic sphere whenever he thought a paddle’s ripples were different from a control paddle’s ripples, the ...