Super-sensitive seal whiskers feel fish breath.

Plunging through gentle swell in the northern oceans in search of food, harbour seals are guided by a cryptic superpower that few fish can evade. ‘Fish produce lots of water flow that remains in the water, even after the fish has gone’, says Wolf Hanke, from the University of Rostock, Germany, and it is these swirling wakes that betray the presence of fish dinners. A hungry seal can sense the tell-tale turbulence left by a passing fish with flow-sensitive whiskers on its snout, before pursuing the hapless victim’s trail. However, seals are not limited to hunting in open water. Explaining that it was apparent from crittercam movies that the diving mammals also stalk seafloordwelling species, Hanke and his colleagues were curious to find out how seals pinpoint well-camouflaged static flatfish that would evade even the sharpest eyes. Could the predators be honing in on the gentle jet of water produced by the concealed fish’s gills with their supersensitive whiskers?