Dolphins recognize their companions by their 'pee taste'

People can identify others not only by their appearance but also by their voice, smell, and texture. A study was announced that bottlenose dolphins living in the sea can 'determine whether they are their friends by the taste of bark and urine' when distinguishing other individuals.

Cross-modal perception of identity by sound and taste in bottlenose dolphins
https://doi.org/10.1126/sciadv.abm7684

Pee pals: Dolphins taste friends' urine to know they're around
https://phys.org/news/2022-05-pee-pals-dolphins-urine-friends.html

Bottlenose dolphins are known to use whistling sounds to reach out to specific individuals, and have been known to remember the proper use of those sounds for over 20 years. However, bottlenose dolphins may notice that strangers are approaching without using sound, and it has not been known how to identify known individuals in remote areas.

A research team at the University of St Andrews presented eight dolphins with urine samples of individuals they were familiar with and those they were not familiar with. At the same time as presenting a sample of urine, a whistling sound recording was played from an underwater speaker to verify the reaction. As a result, it was confirmed that the dolphin 'verifies' the urine sample of the known individual over three times as long as the urine sample of the unknown individual, and recognizes the companion.

Since dolphins do not have an olfactory bulb that senses odors, we are verifying urine with the sense of taste rather than the sense of smell. According to the research team, dolphins often use their jaws to perform 'genital examinations' that touch the other person's genitals, so they may remember the taste of the other person's urine at that time.

The research team said, 'Given the cognitive abilities revealed in our research, dolphins may be able to grasp the reproductive status of the other person from urine and use pheromones to influence each other's behavior. I think it is highly possible that the lipids contained in urine are the key to individual identification. '

Dr. Jason Brock of Stephen F. Austin State University said, 'Dolphins keep their mouths open and collect the urine of familiar individuals longer than strangers. Dolphins are the first vertebrates to taste and socialize. It's an important fact that we found out. '