Photo: RAYMOND ROIG/AFP / Getty Images
Most people can recognize their friends by at least two senses: their faces or the sound of their voices. For more intimate relationships, it is even possible to identify someone by their characteristic scents, such as their perfume. Nevertheless, for bottlenose dolphins, it is the taste that helps them recognize their friends, particularly their urine.
Bottlenose dolphins are found throughout the world in coastal and offshore waters. They are a highly intelligent species and have been known to use sound to communicate and hunt for food. They are also quite social; Although they can travel alone, they often travel in groups of about 12.
Researchers have long known that dolphins can identify themselves and others by their unique characteristic whistles; they even have names that they use for each other. But apparently, that’s not the only way they recognize each other.
A study published in the journal Science shows that the sense of taste allows dolphins to identify their mates through urine and other excretions, according to an international team of researchers.
“Dolphins keep their mouths open and take urine samples longer from familiar people than from unknown peoplefirst author Jason Bruck, from Stephen F. Austin State University in Texas, told the AFP news agency.
“This is important because dolphins are the first vertebrates to have been shown to have social recognition through taste alone.”
Bruck and his team worked with dolphins from the Dolphin Quest resorts in Hawaii and Bermuda who swim with tourists every day. These dolphins live in natural seawater in their social groups so they were ideal for study. By training the animals to give urine samples, the researchers were able to create a collection that was used to present flavors to the dolphins.
For the first part of the experiment, the team presented eight dolphins with urine samples from familiar and unknown individuals, and found that they spent up to three times as much time taking urine samples from those they knew. Genital inspection, when a dolphin uses its jaw to touch the genitals of another individual, is a common part of their interactions.
Then, for the second part, the researchers paired urine samples with recordings of characteristic whistles played on underwater speakers, matched either by the same dolphin that provided the urine or by another animal. It turns out that the dolphins spent more time near the speaker when the vocalization corresponded to the urine sample.
Bottlenose dolphins use characteristic whistles to selectively target specific individuals and can memorize them for at least 20 years. Using taste could also be beneficial in the open ocean, as urine plumes persist for some time after an animal has left, so urine would alert dolphins to the recent presence of an individual, even if not I would have done it verbally.
The researchers believe that it is likely that dolphins can obtain additional information from urine, such as reproductive status or the use of pheromones to influence the behavior of others.
The findings also suggest that dolphins can identify objects that “can be used in mental operations such as planning and mental time travel,” the researchers wrote.
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