Humpback whale
From Memory Alpha, the free Star Trek reference
The Humpback Whale (Megaptera novaeangliae) is a sentient aquatic cetaceous mammal species indigenous to Earth. An adult usually ranges between 12-16 meters in length, and weigh approximately 36 metric tons. This species is well-known for its complex song, which was proven in 2286 to be a full-fledged language. This species went extinct during the 21st century due to over hunting.
In 2286, Admiral James T. Kirk traveled back in time to 1986 San Francisco and retrieved two Humpback Whales to answer an alien probe that threatened Earth. (Star Trek IV: The Voyage Home)
