It looks like bottlenose dolphins may have more tricks up their fins than we knew. New research involving trained zoo dolphins seems to confirm that these mammals can sense electricity, much like other aquatic life. The talent may allow them to better hone in on hidden fish prey and navigate using the Earth’s magnetic field, the authors say.
The biological ability to sense electric fields is known as electroreception. All animals produce a weak electric field, but electroreception has almost exclusively been found in aquatic or semi-aquatic life to date. Some fish can even actively generate electricity as a way to stun and locate their food. A wide variety of water-dwelling organisms possess at least a passive sense of electroreception, including sharks, some amphibians, and certain mammals like echidnas.
About a decade ago, scientists published research suggesting that Guiana dolphins (Sotalia guianensis) have passive electroreception as well. And in 2021, researchers at the University of Rostock in Germany released their own study finding that bottlenose dolphins (Tursiops truncatus) likely have it, too. In both species, this sense seems to be governed by an anatomical structure found along the sides of their snout known as the vibrissal crypts. When these dolphins are born, the crypts house two rows of whiskers, but the hairs fall away and all that’s left on the surface is dimple-like pits.
This new research, published Thursday in the Journal of Experimental Biology, is a follow-up to that latter study by the same team—one intended to better sketch out the limits of electroreception in bottlenose dolphins.
The researchers teamed up with scientists from the Nuremberg Zoo, which currently houses six dolphins. They specifically worked with two bottlenose dolphins named Donna and Dolly. They first trained them to rest their jaws on a metal bar in the water, then to respond to an electric field approaching their snouts by swimming away within five seconds. They then gradually lowered the strength of this field to test the dolphins’ sensitivity.
The findings further validate that bottlenose dolphins can indeed sense electricity, but suggest that some dolphins are better at it than others. Donna, for instance, was a bit more sensitive and able to respond correctly to a weaker field than Dolly. Both dolphins were also worse at detecting pulsing electric fields, though Donna was again better overall.
“One takeaway is that for even such a well-studied animal like the bottlenose dolphin, we were able to show that we still don’t know everything about them yet,” lead author Tim Hüttner told Gizmodo in an email.
The electroreception found in these two dolphin species doesn’t appear to be anywhere as strong as it is in the typical shark, but it’s probably still useful enough for them to find fish hiding underneath sediment within a few centimeters away, the authors say. And the fact that it’s now been found in two species indicates that electroreception could be a common feature in many other dolphins and toothed whales. Other studies have suggested that dolphins also possess a sense of magnetism that acts as a sort of natural GPS for them, though it’s still not clear how this happens. So these dolphins’ electroreception might provide a concrete explanation for that speculated ability as well, Hüttner said.
As for what’s next, the authors would look to see more research testing out the capabilities of this newfound sense, such as how moving dolphins respond to electric stimuli. And it might also be interesting to find out which other small dolphins and toothed whales have electroreception, Hüttner added.