Glowing Mystery Mollusc Sea Slug Found in Deep Sea
Marine scientists have introduced the mystery mollusc, an apple-sized glowing sea slug that swims in the deep, dark midnight zone of the ocean.
Imagine floating deep down in the pitch-black ocean and spotting a creature shining with its own gentle, colourful light. On 12 November 2024, marine scientists from the Monterey Bay Aquarium Research Institute, known as MBARI, introduced the world to an unusual new animal called the mystery mollusc sea slug. Its formal scientific name is Bathydevius caudactylus, and it was discovered living thousands of metres beneath the ocean surface off the coast of California in the United States.
Scientists first caught sight of this strange animal back in February 2000 using an underwater robotic explorer called ROV Tiburon. For over twenty years, researchers analysed video footage and facts from more than 150 separate sightings to finally explain how this remarkable swimmer lives in the deep sea.
What happened?
Senior researchers Dr. Bruce Robison and Dr. Steven Haddock shared their full description in the scientific journal Deep-Sea Research Part I. They revealed that the creature is roughly the size of an apple, measuring between 56 millimetres and 145 millimetres long. While nearly all other sea slugs crawl on shallow sea beds and coastal rocky reefs, this animal is the very first sea slug known to swim freely in the open waters of the ocean’s sunless midnight zone, between 1,013 and 4,009 metres deep.
Because its body is so completely different from any other creature on the planet, scientists created a brand-new scientific family for it, named Bathydeviidae. At its front end, the sea slug has an expandable, bell-shaped oral hood that opens wide like a Venus flytrap plant. It uses this wide hood to scoop up swimming meals like tiny mysid shrimp.
At its rear end, the animal features a flat, paddle-like tail lined with 9 to 16 finger-like projections called dactyls. These projections flutter to help the creature steer and swim smoothly through deep ocean currents. Most fascinating of all, the slug is bioluminescent, meaning its whole body can glow brightly in the pitch darkness. If a deep-sea predator tries to attack, the slug can startle the hunter with a bright flash, and it can even detach one of its glowing tail fingers as a decoy while it paddles away to safety!
Why does it matter to you?
Even if you live far away from the coast in an Indian city like Bengaluru, Jaipur, or Lucknow, this discovery shows us that planet Earth is still full of thrilling natural mysteries. Vast parts of our deep oceans remain completely unexplored, holding wonders that nobody has ever seen before.
It also reminds young learners that great scientific discoveries require lots of patience, teamwork, and curiosity. The scientists spent more than two decades reviewing robotic videos from machines like ROV Tiburon and ROV Doc Ricketts to solve this puzzle. If you enjoy technology, coding, or nature, you could one day use underwater robots to explore the deepest trenches of the Indian Ocean!
Words to know
- Bioluminescent: Able to make and give off its own natural light in the dark.
- Nudibranch: A soft-bodied sea animal that belongs to the sea slug family.
- Midnight zone: The deep layer of the ocean where sunlight never reaches.
- Decoy: A distraction used to fool an attacker so the target can escape.
Did you know?
When threatened by a predator, the mystery mollusc can drop a glowing finger-like part of its tail that keeps shining to distract the hunter while the slug quietly swims away in the dark.
Think about it
Why do you think glowing in the pitch-dark ocean is such a useful superpower for a deep-sea creature? If you could design an underwater robot to explore the ocean floor, what kind of tools would you build into it?
Quick quiz
How does the mystery mollusc sea slug catch its food in the deep ocean?
- It chases fish with sharp teeth
- It traps shrimp using an expandable oral hood
- It burrows into the sandy seabed
See the answer
It traps shrimp using an expandable oral hood
Sources
This story was prepared by the Kids Gazette news desk with the help of AI research and writing tools, using the sources listed above.
