Bottlenose dolphin
From Memory Alpha, the free Star Trek reference.
The bottlenose dolphin (Tursiops truncatus) is an aquatic mammal indigenous to Earth. It is a cetacean species.
When Spock tried to match the sound of the whale probe to the sound of an Earth animal aboard the Klingon Bird-of-Prey HMS Bounty, a bottlenose dolphin was one of the animals shown. (Star Trek IV: The Voyage Home)
Harry Bernard successfuly carved a wooden statue of a bottlenose dolphin with a device that emits a pink/orange bream while in the forced custody of Aldean natives, Accolan and Leda (TNG: "When The Bough Breaks")
