You wouldn’t expect humans to have missed a whole species of giant octopus – but researchers recently revealed that’s exactly what we did. It turns out that the giant Pacific octopus Per Earther – the biggest known octopus on the planet, averaging 110 pounds and 16 feet across – is in reality two species. Alaska Pacific University (APU) undergraduate student Nathan Hollenbeck led the effort to discover what the team is calling the frilled giant Pacific octopus.

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Scientists had wondered if GPO was an umbrella name, referring to more than one species, for decades, according to Earther. In 2012, APU and United States Geological Survey scientists discovered a genetically distinct group of the giant octopus, but only gathered small samples of arm tissue before sending the creatures back to the ocean, so weren’t sure if the groups were also visually distinct. Hollenbeck hoped to unravel the enigma for his senior thesis.

Related: Octopuses are taking over the oceans, and no one knows why

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He found some answers in shrimp trawling bycatch, where octopuses sometimes show up. It didn’t take him long to realize he could identify two types simply by looking at the cephalopods. One was a regular GPO; the other had a frill running along its body, raised skin eyelashes, and two white spots on its head instead of the one of regular GPOs.

“Presumably, people have been catching these octopuses for years and no one ever noticed,” David Scheel, Hollenbeck’s advisor and APU professor, told Earther.

Hollenbeck snipped off small arm pieces – and to see if in the future researchers could avoid that invasive technique, collected DNA with a cotton swab. He was the first to try the less invasive method on an octopus. And both samples confirmed the frilled one is a species distinct from the GPO.

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GPOs can be found from Alaska to California to Japan, but the researchers gathered reliable reports of the frilled giant octopus only from Juneau to the Bering Sea, according to Earther. But the new species could be common in the deeper water habitats they appear to prefer. Frilled giants comprised one third of the octopus bycatch Hollenbeck scrutinized.

The American Malacological Bulletin published the research earlier this year here and here; scientists from the United States Geological Survey and Alaska Resource Education contributed to the second paper.

+ Frilled giant Pacific octopus

Via Earther

Images courtesy of D. Scheel and via and Depositphotos