Harbour seals can use just their whiskers to detect the fattest fish when swimming underwater. They sense the differences in the wake left by the fish which helps determine their size and shape…and therefore the best prey to go for!
Scientists in Cologne Zoo set up an experiment with paddles to mimic the disturbance created by fish. Henry the seal, wearing headphones and a mask to limit his senses, then swam up to one of the two boxes to get a fish reward. They found he could tell the size and shape of the paddle used proving how useful their whiskers are!