Minecraft wiki entry for Dolphin, associated text: To create the sounds that the dolphins make in the game, Mojang Studios' lead sound designer, Samuel Åberg, went to Kolmården Wildlife Park to record real dolphins.[4]
This was also done with pandas.
Dolphins originally had a separate head and body when shown in a clip at MINECON 2017. It is also shown in artwork for Java Edition 1.13.
Real-life dolphins don't suffocate outside of water; they breathe air like all mammals, although they can die of dehydration out of water.
In 2018, a mob vote was held in which Chinese users could vote on which Chinese animal should be added to Minecraft, to promote the release of Minecraft China. One of the options for voting was the possibly extinct Baiji Dolphin. The Panda won the vote and was added into the game.[5]
During development, there were large disagreements between developers over how Dolphins should behave.[6]