How do dolphins recognize each other?

Did you know that dolphins are able to recognize their friends?
And this, thanks to the combination of two elements of identification: the taste of their urine and their unique whistle.
Dolphins are the first vertebrates for which we have demonstrated social recognition through taste alone.
"[They] keep their mouths open and taste the urine of familiar individuals longer [than that of unknown individuals]." Jason Bruck, lead author of the study for AFP
Indeed, according to this study, cetaceans pay particular attention when they are in an area where there is urine belonging to one of their fellow members who has already crossed their path.
Because even long after the animal has left, the urine dissipates only very slowly in the water dissipates very slowly in the water.
On the other hand, cetaceans pay no attention to unknown urine.
The researchers tried the experiment of dissociating whistling and urine to find out their identification abilities.
When the urine does not coincide with the whistle of one of their buddies (as if we put the face of your best friend with a different voice), the dolphin is quite disturbed since he will not pay much attention to it.
On the contrary, when the researchers make coincide whistling and urine, the dolphin explores the area for about 10 more seconds.
Because, like dogs that sniff each other when they cross paths, dolphins can be made to taste each other's urine when they meet.
But dolphins have already lost much of their sense of smell over time.
This raises the question of the impact of marine pollution on their ability to to identify their friends due to an affected sense of taste.
"This may prevent males from identifying females capable of breeding." Jason Bruck, lead author of the study for AFP