They take a deep blow and then they know…
Dolphins recognize their peers by tasting their urine, according to a study published Wednesday. “Dolphins keep their mouths open and collect urine from familiar individuals longer than from unfamiliar individuals,” researcher Jason Bruck of Stephen F. Austin State University in Texas told AFP.
“This is important because dolphins are the first vertebrates to demonstrate social recognition by taste alone,” added the lead author of the study, published in the journal Science Advances. According to the study, using the sense of taste as a detection method could be very advantageous in the open sea, as urine plumes remain for some time after an animal has swum away.
It was previously known that the bottlenose dolphins studied specifically addressed their fellow dolphins with whistling noises. However, it is also common for animals to touch the genitals of their fellow creatures with their mouths, which at least offers the possibility of tasting their urine. Dolphins do not have olfactory bulbs, so unlike other animal species, they cannot identify their conspecifics by smell.
To test their theory, the researchers first trained eight bottlenose dolphins to provide urine samples in exchange for food. The researchers then presented the animals with urine samples from known and unknown conspecifics. They found that the animals spent about three times longer with the urine of known animals than with the urine of unknown bottlenose dolphins.