Dolphins are able to recognise one another by the taste of their urine, a study has found. Researchers at the University of St Andrews have discovered that the mammals can recognise friends and family members without seeing or hearing them. This unique sense of taste allows dolphins to tell between their peers through their urine and other excretions. In order to find this out, Prof Vincent Janik, director of the Scottish Oceans Institute, and his colleagues Jason Bruck and Sam Walmsley tested how dolphins reacted to urine samples from different individuals. According to the study published in the journal Science Advances, the sea creatures were far more interested in urine from animals they recognised than ones they did not know. Janik, the lead author, said: “Dolphins explored urine samples for longer if they came from known animals or when they were presented together with the dolphin’s unique and distinctive signature whistle, an acoustic identifier that works like a name.” The dolphins in the study were from the Dolphin Quest resorts in Hawaii and Bermuda, where their “day job” is swimming with tourists. They live in natural seawater in their social groups so were ideal to study. By training animals to give urine samples when needed, the scientists were able to create a collection that was used across facilities to present known and novel tastes to dolphins. Due to this finding, the researchers believe dolphins have a different experience of taste to other mammals. Janik added: “We still know very little about how the sense of taste works in dolphins. Other studies have shown that they lost a lot of the common tastes that we find in other mammals such as sour, sweet, umami or bitter. But they have unusual sensory cells on their tongue that are probably involved in this detection of individual tastes of other animals.”