Scientists have discovered that bottlenose dolphins, also known as bottlenose dolphins, can sense weak electric fields using vibrating pits on their noses, a feature previously thought to be a residual signature.In experiments on dolphins "Donna" and "Dolly", they found that these mammals can detect electric fields as weak as 2.4 μV/cm and pulsating electric fields generated by fish gills. This ability is thought to help dolphins use the Earth's magnetic field to locate prey and navigate, similar to the electrical sensitivity of sharks.

Bottlenose dolphin pups are born tail first, and their snouts initially have two rows of delicate whiskers, similar to seals' tentacles. However, these whiskers fall out soon after birth, leaving indentations known as "vibration pits." Recently, researchers Tim Hüttner and Guido Dehnhardt of the University of Rostock in Germany began to suspect that these pits may not only be residues, but also have other functions.

Can they allow adult bottlenose dolphins to sense weak electric fields? After initial closer inspection, they found that these residual pits were very similar to the structures used by sharks to detect electric fields, and when they examined whether bottlenose dolphins in captivity could sense electric fields in the water, all animals did.

"It's very impressive," said Deernhardt, who recently published the remarkable discovery and his work on how animals use inductance in the Journal of Experimental Biology.

To find out how sensitive bottlenose dolphins are to the electric fields generated by organisms in the water, Deernhardt and Huetner teamed up with Lorenzo von Fersen of the Nuremberg Zoo and Lars Miersch of the University of Rostock. First, they tested the sensitivity of two bottlenose dolphins, Donna and Dolly, to different electric fields to determine whether the dolphins could detect fish buried in the sand on the ocean floor.

Hüttner and Armin Fritz (Nuremberg Zoo) and a large team of colleagues trained each dolphin to place its chin on a metal rod underwater and then taught them to swim away within 5 seconds of sensing an electric field generated by an electrode above the dolphin's nose.

The research team gradually reduced the electric field from 500V/cm to 2μV/cm and recorded the number of times the dolphins left according to the prompts. The results were impressive: Donna and Dolly were equally sensitive to the strongest electric fields and could leave correctly almost every time. Only when the electric field becomes weaker is it found that Donna's sensitivity is slightly higher. She can sense an electric field of 2.4μV/cm, while Dolly can sense an electric field of 5.5μV/cm.

However, the electric fields generated by living animals are not just static. The pulsating movement of fish gills causes electric fields to fluctuate, so can Donna and Dolly also sense pulsating electric fields? This time, while reducing the intensity of the electric field, the research team pulsed the electric field at frequencies of 1, 5, and 25 times per second. As expected, dolphins were able to sense the electric field.

However, both animals are less sensitive to alternating electric fields than to constant electric fields. Dolly could only sense the slowest electric field of 28.9 μV/cm, while Donna could sense all three oscillating electric fields, including the slowest electric field of 11.7 μV/cm.

So what does this new super sense mean for dolphins in practice? "Sensitivity to weak electric fields helps dolphins search the last few centimeters for fish hidden in the sediment before catching them," Dehnhardt said. In stark contrast, super-electrical sharks can sense the electric fields of fish within 30 to 70 centimeters.

Hüttner and Dehnhardt also suspect that dolphins' electromagnetic abilities could help them on a larger scale.

"This sensory ability could also be used to explain the orientation of toothed whales to the Earth's magnetic field. Dolphins can generate a detectable electric field of 2.5 μV/cm on their bodies when they swim through weak areas of the Earth's magnetic field at a normal speed of 10 meters per second," Deernhardt said. "And if the animals swim faster, they are more likely to sense the Earth's magnetic field and use their inductance to navigate the globe through magnetic maps."

Compiled from /ScitechDaily