George and Gracie, a male and female Humpback Whale
The Humpback Whale (Megaptera novaeangliae) is a sentient aquatic cetaceous mammal species indigenous to Earth. An adult usually ranges between twelve and sixteen meters in length, and weigh approximately thirty-six 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)