Giglioli's whale is an undiscovered species of whale thought to live in the eastern Pacific Ocean and possibly the north Atlantic. Enrico Hillyer Giglioli was an Italian naturalist who started an expedition around the world aboard the ship, Magenta in the 1860s. On September 4th, 1867, the Magenta was about 1,900 km west of Huasco, Chile and 1,800 km off Rapa Nui. Suddenly, Giglioli heard a whale's blowhole, and just off the ship was a greenish-grey whale.
Luckily, the whale remained next to the ship for around 20 minutes, allowing Giglioli to describe the animal in detail. He wrote that it was about 60 feet long. It had a blunt snout, with the top of its head being convex and streamlined. It had a long body that slowly narrowed as it reached the tail. Its skin was velvety and greenish-gray, with a lighter-coloured underside. By far the strangest detail was that the whale had two dorsal fins, unlike any other known cetacean, which either has one dorsal fin or none. The distance between each fin was about 6.5 feet.
The Magenta's commander wanted to kill the whale, but since it was so close to the ship, he couldn't point a cannon at the animal. The whale would blow its blowhole for about eight-to-ten seconds every two minutes. Eventually, the whale became disinterested; it turned on its side and swam away. Since the whale he saw was so different from any other he'd heard of, he considered it a new species and named it Amphiptera pacifica, or "the one from the Pacific with a fin on each side."
Other reports of double-finned whales have occurred. In 1868, the fishing boat Lily spotted a 60-foot whale with two dorsal fins off Stonehaven, Scotland. In 1983, French zoologist Jacques Maigret spotted a large, aquatic animal with two dorsal fins, a trapezoid-shaped head, and a white belly, as it followed the boat he was on between Corsica and mainland France.