Two dolphins have for the first time been recorded having a conversation after scientists developed a microphone that could distinguish the animals' different "voices".
Researchers have known for decades that the mammals had an advanced form of communication of distinctive clicks and whistles to show they are excited, happy, stressed or separated from the group.
But scientists have now shown that dolphins use the volume and frequency of pulsed clicks to form individual "words" that they string together into sentences of five words.
Researchers at the Karadag Nature Reserve, in Feodosia, Russia, recorded two Black Sea bottlenose dolphins, called Yasha and Yana, talking to each other in a pool.
They found that each dolphin would listen to a sentence, without interruption, before replying.
Lead researcher Vyacheslav Ryabov said the exchange resembles a conversation between two people.
