(Image source: A. Liebschner / New Scientist)

BY STEVEN SPARKMAN

ANCHOR JIM FLINK

You're watching multisource science news anlaysis from Newsy.

We already knew dolphins were smart, and they can echo-locate. Now, they’re showing off with yet another sense humans don’t have. A blogger for Discover Magazine explains.

“If you look carefully at the snout of a dolphin, you’ll see two rows of tiny pits, known as vibrissal crypts, When dolphins are born, these pits house whiskers that soon waste away to leave empty craters. ...But these structures are far from useless. In at least one species of dolphin, they can sense electricity.”

The researchers started to suspect the Guiana dolphin’s crypts were sense organs back in 2000.

They dissected a dolphin -- that died of natural causes -- and found the crypts were lined with nerves. Instead of just being an evolutionary leftover, they seemed to still be sensing something. So the researchers came up with a simple test for one of the dolphins. The BBC explains. (Image source: A. Liebschner / LiveScience)

“They trained it to put its head on a ‘rest station,’ where electrodes delivered a tiny electrical signal into the water. When a signal was present, the dolphin received a reward if it swam away; if not, it received a reward for staying put.”

The researchers followed up the test by fitting the dolphin with special headgear.

The plastic shield blocked the dolphin’s crypts. When they tried the same test, the dolphin was unable to sense even very strong electric fields. (Image source: A. Liebschner / New Scientist)

The researchers suspect the Guiana’s aren’t the only dolphin species with the sense. But for now, they’re the only placental mammal known to have the ability. A writer for ScienceNOW says it probably has to do with their environment.

“All animals generate weak electric fields from the activity of their muscles and nerves. Species with electroreceptors can sense this bioelectric field and use it to spot prey that they can't see. And visibility is a real problem for Guiana dolphins, which live … in turbid water and muddy sediments.”

While the dolphin’s extra senses are impressive, sharks have the same ability -- and theirs is about a million times more sensitive.