Researchers Discover an Incredible New Sea Slug in Deep Sea, Nickname it 'Mystery Mollusc'

Researchers were stunned when they found a sea slug in the Midnight Zone, between 1,013 and 4,009 meters (3,323 to 13,153 feet). The discovery was surprising because no other sea slug had been found in such depths, IFL Science reported.

Bathydevius caudactylus caught attention because of the depth it was swimming in and due to its various eye-catching features. Findings regarding the discovery of particular species have been published in the journal Deep Sea Research Part I.

Monterey Bay Aquarium Research Institute senior scientists Bruce Robison and Steven Haddock first spotted Bathydevius caudactylus in February 2000 during a deep-water dive expedition offshore of Monterey Bay, CNN reported. Since then, the organization has recorded close to 150 sightings of the slug, which they initially dubbed as a 'mystery mollusk.'

The team has located the slug in waters off the Pacific Coast of North America, ranging from Oregon to Southern California. National Oceanic and Atmospheric Administration has also reported Bathydevius caudactylus's presence in the Western Pacific.

A small sample of the marine being was taken and sent to the lab for analysis, CNN reported. Examination revealed that the being was a nudibranch, but one that had undertaken several adaptations to survive in the midnight zone. Nudibranchs are soft-bodied marine gastropod mollusks that are commonly known as sea slugs.

Haddock stated that Bathydevius caudactylus looked "like a megaphone with a feathered tail," CNN reported. They don't share a lot of similar physical features with other slugs, which is why researchers couldn't identify Bathydevius caudactylus's origins at first glance. The animal sports a massive bowl-shaped hooded structure at one end, and a flat tail that appears to be fringed with fingerlike projections on the other end, according to the study. The being's internal organs are on full display.

In terms of feeding Bathydevius caudactylus does not straight-up attack its prey, instead, they go for much more subtle methods, CNN reported. "For this nudibranch and some other deep-sea animals, they engulf their prey," Haddock explained. "Instead of being stronger than their dinner, their flexibility absorbs the struggling movements and smothers them as if with a wet blanket."

Researchers were surprised to find a sea slug at such depths. "The deep water column is maybe the last place you’d expect to find a nudibranch," Robison said.

"It’s sort of like finding hummingbirds near the peak of Mt. Everest. The midnight zone is cold and dark and very forbidding to us terrestrial creatures, yet it is filled with life, albeit life forms adapted to a very different set of challenges than we face. Almost every aspect of Bathydevius reflects an adaptation to this habitat: anatomy, physiology, reproduction, feeding, behavior; it’s unique."

Experts have continued to work hard on the examination of Bathydevius caudactylus and the adaptations they have undertaken to live in the Midnight Zone of the ocean, CNN reported. Researchers have faced a lot of issues when it came to analyzing the midnight zone. Accessing the area is fraught with difficulties, and examining the beings found in the area is even more complicated. Hence, Bathydevius caudactylus is such a crucial finding for marine scientists.

"We’ve invested more than 20 years in understanding the natural history of this fascinating species of nudibranch," Robison said. "Our discovery is a new piece of the puzzle that can help better understand the largest habitat on Earth."