Already equipped with an impressive sonar system, new research reveals that dolphins have an extra ability that evolves as they mature in the space where their baby whiskers once were. The super sense may help them navigate and find hidden food sources.
Dolphins' sonar ability, known as echolocation, is fairly legendary in the animal kingdom. This ability is so accurate that the mammals, which are technically whales, can use it to distinguish between a golf ball and a ping-pong ball underwater based on the densities of the two objects. But that's not where the creatures' impressive abilities end.
They also have eyes that allow them to see in two directions at once; skin that secretes an antibacterial gel to ward off parasites and barnacles; they can get enough thrust to reach 30 mph; and they turn off half their brains at a time in order to get rest. A 2019 study also revealed that they have super immune systems that grant them protection from antibiotic-resistant bacteria. Now, a new study out of the University of Rostock (UR) in Germany adds another impressive skill to the dolphin's roster of powers: the ability to sense weak electric fields.
Two UR researchers took a closer look at the small pits that are left behind after young bottlenose dolphins shed the thin whiskers they are born with. They realized that the pits looked like the same structures that allow sharks to detect electrical fields and designed a study to see if they functioned the same way for the dolphins.
They first trained two dolphins at the Nuremberg Zoo to rest their jaws on a metal bar submerged in a pool. Then, they trained them to swim away whenever they sensed an electrical current being produced just above their snouts. One dolphin was able to sense signals down to those measuring just 5.5 microvolts/cm, while the other was even more sensitive, picking on a current measuring 2.4 microvolts/cm. One microvolt is equal to one millionth of a volt.
The dolphins also showed a high degree of responsiveness when the researchers pulsed the electrical current rather than keeping it steady. This, they say, more accurately resembles the kind of weak and inconstant electrical field that would be emitted by the fish the dolphins prey upon.
"The sensitivity to weak electric fields helps a dolphin search for fish hidden in sediment over the last few centimeters before snapping them up," said study co-author Guido Dehnhardt. That's quite a bit different than the use of the sense in sharks, which can use it to detect the electrical fields of fish up to 70 cm (2.3 ft) away.
The researchers also believe that the ability, known as electroreception, could help dolphins navigate using the earth's magnetic field and that it may explain occasional beach stranding of the animals due to fluctuations in this field.
Their research has been published in the Journal of Experimental Biology.
Source: The Company of Biologists via Phys.org
