Dolphins Develop a New Sense

We all know that dolphins are smart. And we know they have more senses than people, adding echolocation to the senses of sight, sound, smell, taste and touch. Now scientists have tested and confirmed a seventh sense in at least one species of dolphins.

The Guiana dolphins, which live in the muddy coastal and river waters of South and Central America, have the ability to sense electrical fields. Sharks possess the same bioelectric capability but theirs is much stronger than dolphins.

Scientists made this discovery after ten years of study. When the studied little pits around the dolphin beaks where whiskers used to grow, they discovered they were not useless vestigial features but contained nerves. Eventually, researchers found that the vibrissal crypts are key sensing organs.

German biologist Wolfe Hanke from University of Rostock led the team that made the sensory discovery. He says, “We were really surprised to find this in the dolphin. Nobody had expected it.”

To test the theory, marine biologists trained a dolphin to place its head on a rest station where electrodes delivered a tiny electrical signal in the water. If the signal was present the dolphin would receive a reward for swimming away and if there was no signal the dolphin would be rewarded for staying at the rest station.

When researchers covered the vibrissal crypts to block the signal, the dolphin could no longer perform the task accurately, leaving scientists to conclude that the little snout craters are keen bioelectrical sensors that help Guiana dolphins find prey by mapping out the weak electrical signal given off by fish.

This discovery makes dolphins the first mammals to have this special sense, called electroreception.