Pee pals Dolphins can recognise their friends by tasting their URINE, study reveals
Experiments show dolphins recognise someone they know by tasting their wee
Lipids in the urine likely allow dolphins to identify individual chemical signatures
Because they don’t have olfactory bulbs they have to rely on taste and vocal calls
Similar to how dogs sniff urine left by other dogs, dolphins can recognise each other by tasting their urine, a new study reveals.
In experiments, dolphins showed signs of recognition when tasting the urine of another dolphin that they’d already met.
Dolphins do not have olfactory bulbs, so they have to identify which other dolphins have been in the area using taste, researchers say.
It’s thought that molecules known as lipids that are present in the urine allow dolphins to identify the individual chemical signatures of their friends.
Genital inspection, in which a dolphin uses its jaw to touch the genitals of another individual, is common in their social interactions, so it provides a good opportunity to learn these chemical signatures.
Dolphins may also be able to extract biological information from others’ urine, such as reproductive state.
The new study was authored by Dr Jason Bruck, assistant professor of biology at Stephen F. Austin State University in Nacogdoches, Texas, as well as Sam Walmsey and Vincent Janik at the University of St. Andrews in Scotland.
‘It is likely that dolphins use a lipid taste receptor to identify urine cues in their fellow dolphins,’ Bruck said.
‘We are moving forward with signature whistle playback experiments to determine how different social relationships may be perceived in dolphin community ecology.’
It’s already known that dolphins also use signature whistles – individual acoustic calls that they invent during the first year of life, much like how humans use names.
Dolphin calves will eventually make their own individual whistle, but in the first stages of life, they use their mother’s.
For the new study, Bruck conducted experiments in Bermuda and Hawaii at facilities where the public and scientists can view and meet dolphins in sheltered lagoons.
He presented eight bottlenose dolphins (Tursiops truncatus) with urine samples from other dolphins who they were either familiar or unfamiliar with.
Overall, the dolphins spent around three times as long sampling urine from those they knew – a stronger indicator of recognition.
‘Dolphins keep their mouths open and sample urine longer from familiar individuals than unfamiliar ones,’ Bruck told AFP.
‘This is important because dolphins are the first vertebrate ever shown to have social recognition through taste alone.’
Bruck then used underwater speakers to present the dolphins with audio calls of other dolphins at the same time that they were presented with urine samples.
He paired playbacks of signature whistles of known dolphins with urine samples from either the same dolphin or a different but familiar animal.
Dolphins investigated the presentation area longer when the audio and urine sample matched than when they mismatched, he found. This suggests urine and audio calls are used together for recognition.
Bottlenose dolphins use signature whistles to selectively address specific individuals, and can remember these for over 20 years.
Using taste as well could be highly beneficial in the open ocean because urine plumes persist for a while after an animal has left.
So urine alerts dolphins to the recent presence of that individual even if it had not signaled its presence vocally.
Somewhat surprisingly, the same gene that allows dolphins to identify lipids in urine is present in humans, Bruck and his colleagues also report.
The gene, called CD36, is present in most humans and allows us to know when we have had enough to eat.
Studying the gene in dolphins could therefore improve understanding of how it works in people.
According to Bruck, future studies could investigate how commercial and industrial chemicals might affect ‘urine cuing’ in dolphins.
‘We may find that oil spills, chemical runoff and other human effects can impede the dolphins’ natural ability to chemically signal to one another,’ he said.
‘This might prevent males from identifying reproductively capable females or diminish dolphins’ abilities to recognize individuals through honest signals.’
The study has been published in the journal Science Advances.
Source: daily mail
Pee pals Dolphins can recognise their friends by tasting their URINE, study reveals/Pee pals Dolphins can recognise their friends by tasting their URINE, study reveals