The newly described species was announced in the journal Zootaxa after researchers confirmed that the unusual octopus had never been documented before.

The animal was first spotted during a 2015 deep-sea expedition aboard the exploration vessel E/V Nautilus. The mission was carried out in partnership with the Charles Darwin Foundation (CDF) and the Galápagos National Park Directorate. Researchers used a remotely operated underwater vehicle (ROV) to investigate the seafloor near Darwin Island, located at the northern edge of the Galápagos archipelago.

Deep-Sea Discovery Near an Underwater Mountain

As the ROV explored an underwater mountain roughly 5,800 feet (1,773 meters) below the ocean surface, researchers noticed something unusual moving across the seafloor: a tiny octopus with a striking blue color.

The scientists' immediate reactions were captured in the expedition audio recordings.

"He's tiny!"

"It's blue!"

Using the ROV, the team collected the octopus specimen and also recorded video footage of two others that appeared to be the same species. After returning to the Galápagos, the researchers brought dozens of deep-sea specimens to the Charles Darwin Research Station for examination.

Among all the collected animals, the little octopus immediately stood out. About the size of a golf ball, it looked unlike any known species. Researchers at the station contacted octopus expert Janet Voight and sent her photographs of the animal for identification.

"Right away, I knew it was something really special," says Voight, curator emerita of invertebrates at the Field Museum in Chicago and the lead author of the study describing the new species. "I'd never seen anything like it."

Scientists Use CT Scans To Study Rare Octopus

The specimen was carefully preserved in alcohol and formalin before being shipped from the Galápagos to Chicago, where Voight examined it at the Field Museum.

Normally, identifying a new octopus species requires scientists to dissect the specimen and closely study features such as the mouth, beak, and teeth. However, the researchers faced a major challenge because they had only one confirmed specimen.

"When you describe a new species of octopus, you have to look at all the parts, including the mouth, the beak, and the teeth. And to see those things, you have to cut the specimen open. We only had the one specimen, so I didn't want to take it apart," says Voight.

Instead, the team turned to advanced imaging technology. Stephanie Smith, manager of the Field Museum's X-ray computed tomography laboratory, helped create highly detailed micro CT scans of the octopus.

"Because CT imaging is non-destructive, it's especially important for type specimens like this one. And that's great for me because people are often bringing me these incredibly rare and stunningly beautiful specimens that I get the privilege of virtually opening up," says Smith, a co-author of the paper describing the new species. "There's nothing like spending the day looking at something no other human has ever seen."

CT scanning works by combining thousands of X-ray images into a detailed 3D model that reveals both the exterior and internal anatomy of an object without physically cutting into it.

For the tiny blue octopus, the scans provided clear views of internal organs and mouth structures, allowing scientists to officially classify it as a new species and better understand its relationship to other octopuses.

"What really struck me was that the scan of the little octopus revealed so much information on its internal organ systems -- usually, soft-part imaging using micro CT requires the use of heavy-metal-based contrast agents whose use would not be desirable with such a rare specimen. This made the 3D modeling of relevant organs really an easy task," says Alexander Ziegler, a researcher at the University of Bonn in Germany and senior author of the paper.

A New Species Highlights Ocean Mysteries

The octopus has been named Microeledone galapagensis. Beyond the discovery itself, the species also marks an important milestone for Voight, who has spent more than 40 years studying octopus evolution. This is the first time she has officially led the description of a new octopus species.

"These are little octopuses that live in the deep sea, and hardly anybody on Earth has ever gotten to see them. I just feel lucky that I got to work with them," says Voight. "If you took all the land on Earth and pieced it together, you would not cover the Pacific Ocean. The oceans are so big, and there's so much left to explore."

Researchers say discoveries like this are also important for protecting fragile ocean ecosystems that remain poorly understood.

"When we were sorting through dozens of specimens collected during the expedition, this tiny blue octopus fascinated us," said Salome Buglass, marine scientist at the University of California of Los Angeles, former researcher at the Charles Darwin Foundation and co-author of the paper. "There was something unusual about it, so we went out of our way to find the right person to help us identify what it was. Getting the specimen to Janet was a long process, but one I would gladly repeat if it means getting to know the most precious parts of our ocean just a little bit better. Discoveries like these remind us how much of the deep ocean in Galápagos remains unexplored. Every new species helps us better understand these hidden ecosystems and why protecting them matters."