B. caudactylus, however, seems to get around more like a jellyfish than a sea slug.
The hood of B. caudactylus can also act something like a Venus flytrap.
B. caudactylus is gelatinous and transparent, with a smooth heart, textured digestive gland, and whitish brain that can easily be seen from the outside.
Like many other bioluminescent organisms in the deep sea, it glows blue, since red light does not transmit far at those depths.
Deep Sea Research, 2024.
The deep ocean contains some of the most strange creatures on the planet. The identification of one of these creatures took 20 years because so little was known about it. From there, things only got stranger.
From 2000 to 2021, several deep-sea missions saw the organism’s unique, glowing presence, but it was only called “mystery mollusk.”. Using the remotely operated vehicles (ROVs) of the Monterey Bay Aquarium Research Institute (MBARI), a group of researchers has now examined a large amount of video from previous mystery mollusk sightings in order to observe and gather samples. The first and only nudibranch known to survive at such depths, they have finally confirmed that it is a nudibranch and given it a name.
This nudibranch, now known as Bathydevius caudactylus, inhabits the 1,000–4,000 m (3,300–13,100 ft) deep bathypelagic or midnight zone of the ocean. Its genes are different enough to make it the first member of a new phylogenetic family, and it is bioluminescent, moves like a jellyfish, and eats like a Venus flytrap.
The MBARI research team stated in a study recently published in Deep Sea Research that “this surprising nudibranch is distinguished from all previously described species by anatomy, diet, behavior, bioluminescence, and habitat, and genetic evidence supports its placement in a new family.”.
That a…?
Since their “foot,” which they use to crawl around when not swimming, is located directly beneath their guts, nudibranchs are gastropods, which literally translates to “stomach foot.”. Both terrestrial and aquatic snails and slugs belong to the same group as them. B. But rather than moving like a sea slug, caudactylus appears to move more like a jellyfish. Like many jellyfish, it primarily swims by opening and closing its oral hood to propel itself backward through the water.
The hood of B. Additionally, caudactylus can function similarly to a Venus flytrap. It is employed to trap prey even though it lacks the hinged structure of the plant’s leaves. The prey, which are usually small crustaceans, are then forced to the mouth at the rear of the hood.
Additionally, the nudibranch appears to have a special method of avoiding becoming food. Similar to the tails of certain lizard species, the projections at the end of its tail, called dactyls, can separate if necessary. These dactyls may be a lure used to deceive predators while the nudibranch swims away, according to the MBARI team. They subsequently grow back.
A. The transparent, gelatinous caudactylus has a whitish brain that is easily visible from the outside, a textured digestive gland, and a smooth heart. Rhinophores are two chemosensory organs on its head that resemble antennae and are likely used to detect prey. To move around on the ocean floor, one needs a cylindrical foot. It glows blue, like many other bioluminescent creatures in the deep sea, because red light does not travel very far there.
It seems almost unnatural.
So, how is B? To find out, the researchers sequenced three of the caudactylus’ genes and compared them to those of two well-known nudibranch groups, the dorids and the cladobranchs. While each B’s sequences. Despite differences between the caudactylus and other groups, the mystery mollusk shared enough traits to be categorized as a nudibranch.
In the same study, the MBARI team stated that “the three genes… supported that Bathydevius is a divergent genus of Nudibranchia.”. The rest of the cladobranch and dorid nudibranchs are its sisters, and the genus Bathydoris is its sister. “”.
The genetic ties to other nudibranchs notwithstanding, there are numerous areas where B. caudactylus deviates. It is not the only hooded nudibranch that traps prey, and its predation of crustaceans is uncommon for nudibranchs, which typically eat cnidarians like jellyfish. Additionally, it is devoid of a radula, which is a tongue-like structure used by most nudibranchs for eating. Despite having genetic distance, Melibae Leonina shares all of these traits. The scientists believe that the two species’ similarities are due to convergent evolution, which is the process by which organisms with different genetic backgrounds acquire traits in common.
In nudibranchs, bioluminescence is also rare. B. Caudactylus is the seventh known bioluminescent gastropod and only the third known bioluminescent nudibranch. It is, once more, only distantly related to the other species.
Despite being on Earth, the deep ocean is the closest thing to an alien environment. A large portion of it is still poorly understood or unexplored. This could indicate that there are still a lot of unidentified species out there. By preserving their ecosystems, we may be able to discover more unusual and intriguing life forms, like glowing sea slugs.
2024: Deep Sea Research. 10.1016/j is the DOI. DSRs. 2024.104414.
