A group of killer whales once thought to be genetic anomalies may in fact be a species all their own, according to a recent study in the journal Polar Biology.
The rarely-seen “type D” orcasâ€”which live in the Southern Oceanâ€”are one of four varieties of killer whale. Researchers recently sequenced type D’s genome using material collected from a museum skeleton from 1955.
Scientists first spotted type D killer whales in 1955, when a pod of them washed ashore on a New Zealand beach. The stranding stood out as unusual because of the whales’ strange appearance. While typical killer whalesâ€”types A, B, and Câ€”have streamlined bodies and large, white eye-patches, type D whales have tiny eye markings and large, bulbous heads.
According to Robert Pitman, a marine biologist at the U.S. National Marine Fisheries Service, and a co-author of the new study, for many years researchers thought the whales were the result of genetic mutations because there were no other known sightings.
But some 50 years after the New Zealand stranding, a group of researchers, including Pitman, took a closer look at the documentation of the event. They unearthed other accounts of the weird whales, and found that the New Zealand pod was not the only sighting in history.
“We started seeing photos of this type of animal from various places, all around the Antarctic waters,” Pitman said. “The weather is bad down there all the time,” he said. “That’s why the whale escaped notice from scientists for so many years.”