A paper published in the peer reviewed journal Journal of Comparative Physiology A has shown that Florida manatees (Trichechus manatus latirostris) have the ability to sense water movements thousands of times smaller than the width of a human hair. They do this via sense receptors in their facial whiskers.
The research team from Mote Marine Laboratory conducted experiments with two captive manatees named buffet and Hugh. They found that:
“When water rippled at 150 Hertz (times per second), Buffett and Hugh could feel water movement around and below one nanometer, respectively. For comparison, a human hair measures 80,000-100,000 nanometers wide. When the scientists lowered the ripple to 10 Hz, the manatees could detect water movements of 1,000 nanometers — still much smaller than a hair’s width.”