For a bottlenose dolphin, a friend's identity can arrive as a taste in the water. In experiments with trained dolphins at managed natural-seawater facilities, researchers presented urine samples from familiar and unfamiliar animals. The dolphins investigated familiar samples for longer, evidence that the cue carried information about a known individual rather than merely something chemically interesting.

The stronger test crossed senses. Researchers paired the taste cue from a familiar dolphin with recordings of signature whistles—the individually distinctive calls dolphins use. Subjects responded differently when the urine and whistle belonged to the same animal than when the cues were mismatched. They were not just remembering a smell-like flavor or a sound in isolation; they connected two kinds of evidence to one social identity.

The study shows individual recognition by taste and cross-sensory matching under managed conditions. It does not establish every message a dolphin might extract from urine, and it does not turn one sample into a complete social biography. Still, the finding expands the idea of a dolphin's address book: a familiar name can be recognized by ear, then matched to chemistry drifting through seawater.