A slug like no other
Usually, nudibranchs – or sea slugs – live near the seabed or in coastal areas. But this one decided to hide a little deeper. Discovered between 1,000 and 4,000 meters deep, in the “midnight zone”, also called the bathypelagic zone, where light never penetrates, this slug swims freely in dark waters thanks to a flat tail and a gelatinous cap which gives it allows water to be propelled to move. And this is a first for its species.
But that's not all. This small creature, translucent and the size of an apple, has a unique ability: it glows in the dark. Its bioluminescence serves to dazzle its predators or, in case of danger, to detach a luminous part of its tail to distract the enemy. A bit as if she were saying: Here, take care of that while I go!
Well-thought-out survival strategies
On the menu of this slug, we mainly find shrimp. To catch them, it uses a hood that closes like a trapdoor, a bit like a carnivorous plant. And to avoid being noticed, its transparent body blends into the darkness. Practical when you live in an environment where everything is a question of survival.
On the reproduction side, Bathydevius caudactylus also has its well-established technique. Hermaphrodite like other nudibranchs, it anchors itself at the bottom of the ocean to lay its eggs before resuming its wandering in the depths.
A mystery revealed thanks to technology
Without the Monterey Bay Aquarium's advanced underwater robots, this discovery would have remained in the shadows. These devices made it possible to film more than 150 appearances of the animal and capture spectacular images of its bioluminescence. Genetic analyzes then confirmed that this is an entirely new family of nudibranchs, a rare addition to the tree of marine life.
