Scientists Find a Glowing Deep-Sea Creature Living on Another Animal — And It’s Unlike Anything Seen Before

A few hundred meters below the ocean’s surface, sunlight disappears completely. There are no waves, no blue horizon, just darkness, cold water, and crushing pressure.

And yet, something down there glows.

During a 2022 biodiversity expedition off Western Australia aboard Australia’s national research vessel, RV Investigator, scientists collected specimens from deep waters. Years of careful laboratory work followed - measuring, comparing, sequencing DNA. By 2025, researchers formally described two new species: a bioluminescent shark and a tiny porcelain crab that lives attached to another animal.


These weren’t lucky guesses. They were the result of structured marine surveys, taxonomic analysis, and genetic confirmation published in peer-reviewed research.

The West Australian Lantern shark

The newly described shark, Etmopterus westraliensis, now called the West Australian lantern shark, was recorded at depths reaching about 610 meters. It belongs to a group of deep-sea sharks known for producing their own light.

Along its underside and flanks are photophores — specialized organs that emit light. Marine biology research shows that bioluminescence, the production and emission of light by living organisms, often serves as camouflage in deep-sea animals through a process called counterillumination. By producing faint light on their bellies, sharks can blend with the dim glow filtering down from above, hiding their outlines from predators or prey below.

Bioluminescence is a common deep-sea adaptation. Many fish, squid, and comb jellies generate light via chemical reactions involving luciferin compounds.

For the lantern shark, that soft glow may also help with communication or species recognition. In darkness, light becomes a signal system.

Finding a new shark species in the 21st century may sound surprising. But in deep waters, biodiversity remains largely undocumented. Each carefully examined specimen adds another piece to the puzzle of how life survives under extreme pressure and permanent night.

A Tiny Crab With a Powerful Partnership

The second discovery is much smaller but equally striking.

Porcellanella brevidentata is a porcelain crab, only about 15 millimeters long. It has a pale, almost translucent body. But its most interesting feature is not its size — it is where it lives.

This crab makes its home among sea pens, which are soft corals that anchor themselves into the seabed and extend feather-like branches into the current. Academic ecological studies describe this kind of close, long-term relationship between two different species as symbiotic, meaning both benefit in some way.

The crab shelters within the sea pen’s branches, gaining protection from predators and direct access to flowing water rich in microscopic food. Porcelain crabs are filter feeders. They use fine hair-like structures on their mouthparts to capture plankton drifting past.

By positioning itself on the sea pen, the crab increases its feeding efficiency. Research on marine symbiosis suggests that such arrangements may also benefit the host. Crab movement can improve local water circulation around coral tissues, potentially aiding nutrient exchange.

In deep ecosystems, survival often depends on cooperation.

How Scientists Confirm a Discovery

Identifying a new species requires more than visual differences.

After collection, scientists conduct detailed morphological comparisons — measuring body proportions, examining teeth, counting fin rays, and studying shell structure. Morphological comparisons involve looking at the physical features and structures of organisms to identify differences. But modern taxonomy, the science of classifying species, increasingly relies on molecular genetics.

For Porcellanella brevidentata, researchers used DNA sequencing alongside physical comparisons. Genetic markers help confirm that a specimen is not simply a regional variation of a known species but a distinct lineage.

DNA barcoding has become a cornerstone of marine biodiversity research. DNA barcoding is a method of identifying species using a short genetic sequence from a standardized region of the genome. Studies show that genetic tools often reveal hidden diversity in deep-sea habitats, where many species appear nearly identical on the surface.

Without these methods, much of ocean life would remain misclassified or overlooked.

Life Built for Pressure and Darkness

The deep sea presents extraordinary challenges. Temperatures hover near freezing. Pressure rises dramatically with depth. Food is limited and often arrives as organic particles drifting down from surface waters.

Bioluminescence helps animals communicate, hide, or hunt, while symbiotic living allows species to share resources and reduce risk.

These are not random traits. They are evolutionary responses shaped over millions of years.

Research in deep-sea ecology shows that even a single expedition can reveal dozens of undescribed species. The 2022 voyage that uncovered these two organisms has already led to nearly 20 new species descriptions, with many specimens still under analysis.

The ocean floor remains one of Earth’s least mapped biological frontiers.



What Remains Hidden Beneath

When we picture the ocean, we often think of waves and beaches. But most of the planet’s living space lies far below that surface.

In total darkness, a small shark glows softly to survive. A tiny crab clings to coral branches for shelter and food. Around them, countless other species move unseen.

Every expedition reminds us of something simple: we have explored more of the Moon’s surface than our own deep ocean.

And somewhere in that darkness, more light is waiting to be discovered.