The Dolphin's Sixth Sense

By Ashley Peterson

If you look closely at the snout of a dolphin, you'll notice two rows of tiny pits. At some point in the dolphin's evolutionary past, these pits, known as vibrissal crypts, housed whiskers, and it has long been thought that these crypts no longer served a purpose — until now. In at least one species of dolphin, the Guiana dolphin, they can sense electricity.

All living organisms generate tiny yet measurable electric fields. Researchers in Germany have recently discovered that the Guiana dolphin uses its vibrissal crypts to detect changes in the electric fields in order to find food. While this fascinating capability, known as electroreception, is fairly common among fish, only a small number of mammals are able to locate their prey in this way. Until recently, the exclusive list included only the four species of echidna (aka, spiny anteaters) and the duck-billed platypus.

The Guiana dolphin is the first marine mammal to join the list, and researchers suspect it’s not the only dolphin with this ability. Dolphins are already known to navigate and hunt using sonar, which is when they produce clicks underwater and detect their return after being reflected to measure distance. They may have lost their close-range whiskers due to this ability, but  that doesn’t mean the crypts left behind were rendered useless.

Dolphin Tricks

To test their idea, the German researchers worked with Paco, a Guiana dolphin living in captivity. They taught Paco to swim next to a device that could create a tiny electric field. Then the team taught Paco to swim away from the device if he detected any changes in the electric field. The scientists determined that Paco was able to detect tiny electric variations, except when his snout was covered in plastic. After conducting 186 trials of the experiment, their theory was confirmed that the dolphin uses its vibrissal crypts to detect the electric fields created by its prey.

German biologist Wolfe Hanke led the team that made the sensory discovery. He said, "We were really surprised to find this in the dolphin. Nobody had expected it."

Evolutionary Advantage

While this is a surprising new discovery in the animal world, it makes perfect, practical sense for dolphins to evolve in this way. Visibility is often drastically reduced in the murky waters these mammals call home, and the ability to electrically sense their dinner may make all the difference when it comes to survival. Nevertheless, the study opens an exciting door to researchers who have a whole new sensory system to explore and further emphasizes that the animal kingdom will continue to surprise us.

Classroom Discussion

• Can you name any other animals that possess a sixth sense?
• How can humans benefit from studying the evolution and behavior of animals?