When a 24-foot whale carcass washed up on the beach of a remote Alaskan island in 2014, a researcher was pretty sure it was a dark version of a Baird's beaked whale, National Geographic reports. But per a new study published in Marine Mammal Science, it was an entirely new whale species altogether—a black cetacean referred to as katasu, or "raven," by Japanese fishermen who'd encountered it from waters off of northern Japan all the way to Alaska's Aleutian Islands, a press release notes. The katasu had been talked about since the 1940s by the fishermen, who said they only very occasionally saw them in groups, and only for a couple of months out of the year. "It's a really big deal," study co-author Paul Wade tells National Geographic. "On land, discovery of new species of large mammals is exceptionally rare."
And the research team from the National Oceanic and Atmospheric Administration went through all the paces to make sure this whale specimen in the Berardius genus wasn't just another type of Baird's whale (which are usually more gray in color) or another beaked whale called the Arnoux: They checked out DNA from 178 beaked whales, scrutinized Japanese whaling records, and even took down a whale skeleton displayed in an Alaskan high school gym, finding eight specimens of the new species that they'd previously thought were Baird's variations. It "reveals how little we know and how much more work we have to do to truly understand these species," co-author Erich Hoyt says in the release. (Another surprising whale find: They may grieve for their young like humans.)