http://thenewdaily.com.au/news/world/2016/09/12/scientists-record-dolphin-conversation/
"But now, using an underwater microphone, researchers have recorded dolphins forming individual words, sentences and even wait for the other to finish their sentence before replying."
"Lead researcher Dr Vyacheslav Ryabov said: “Essentially, this exchange resembles a conversation between two people,” the UK’s The Telegraph reported."
So long and thanks for all the fish!