Decisive sea otters use paws and whiskers to distinguish objects by touch
(PHYSorg.com Biology)

When dinner is encased in a robust shell, brute force is often the only solution, but ingenious sea otters (Enhydra lutris) have been more ingenious. Some pound clams and snails on a rock balanced on their chests, while others skilfully crack open shells to satisfy their voracious appetites. Describing sea otters as eating machines, Sarah McKay Strobel from the University of California Santa Cruz (UCSC), USA, explains that they devour 25% of their own body weight each day just to remain warm. Yet little was known about their hunting tactics because the shy mammals stop seeking food when human divers are near. Suspecting that the enigmatic animals do not rely on smell or vision to located dinner in the cloudy Monterey Bay waters, Strobel and PI Colleen Reichmuth wondered whether the dextrous creatures might depend instead on the sensitivity of their whiskers and paws to hunt by touch. They publish their discovery that sea otters` paws and whiskers are remarkably sensitive, allowing the mammals to distinguish 2.28mm grooves from 2mm grooves with their paws, and 2.48mm groves from 2mm grooves with their whiskers, with just a single touch in Journal of Experimental Biology.