Scientists have long known that dolphins identify themselves using so-called signature whistles that are different for each dolphin and that they address one another by imitating such whistles. But researchers were uncertain if this copying showed that dolphins associate signature whistles with individual identity or with a more general concept such as “friend.”

Recently, scientists learned that not only do bottlenose dolphins demonstrate name recognition, they also replicate this recognition with another sense: taste.

By tasting each other’s urine and recognizing the source, the dolphins showed that they could keep track of dolphin identities using two types of sensory input. This means the animals could create and store a mental concept of other dolphins, according to the new study.