It measures just a few millimetres, is almost completely transparent and managed to remain unknown to science despite living in one of Europe’s most studied seas.
Scientists from the University of Alicante have identified a new species of jellyfish in the waters off El Campello.
Named Copula lucentia, the tiny creature measures between just one and seven millimetres and belongs to the cubozoans, commonly known as box jellyfish because of the distinctive shape of their bell.
The discovery is particularly unusual because Copula lucentia becomes only the second box jellyfish species documented in the Mediterranean.
And, so far, scientists have only found it off El Campello.
Small enough to be easily missed
There is little danger of mistaking Copula lucentia for one of the larger jellyfish occasionally washing up on Costa Blanca beaches.
Even the largest specimens measure only around seven millimetres.
Its body is almost transparent, making an already tiny animal particularly difficult to spot in the water.
Researchers found specimens at depths of less than 1.5 metres in an environment containing rocky and sandy seabeds alongside seagrass meadows.
Scientists initially became interested because the jellyfish did not quite match known species.
Its small size and several physical characteristics suggested they might be looking at something unusual.
Scientists used genetics to confirm the discovery
Researchers collected the original specimens between 2016 and 2018.
The team then combined detailed examination of the animals with genetic analysis and worked with international specialists to establish exactly what they had found.
The results showed that the jellyfish belonged to the genus Copula, but its anatomy and genetics differed sufficiently from known members of the group to classify it as a separate species.
Researchers published the scientific identification in 2024.
Eva Fonfría, a University of Alicante researcher and first author of the study, was among the scientists involved in establishing its identity.
Why is it called Copula lucentia?
The new species also carries a distinctly local name.
Scientists chose lucentia as a reference to Lucentum, the Latin name associated with ancient Alicante.
That gives the Costa Blanca connection a permanent place in the animal’s scientific identity.
It could prove particularly appropriate because researchers have not yet documented the species anywhere else.
Only the second Mediterranean box jellyfish
The discovery becomes even more significant because of the group to which the animal belongs.
Until now, the Mediterranean had only one documented box jellyfish species, Carybdea marsupialis, first described by Carl Linnaeus in 1758.
Copula lucentia becomes the second.
Box jellyfish are best known for their roughly cube-shaped bells, although the group contains numerous species with very different characteristics.
The discovery does not mean Costa Blanca swimmers suddenly need to worry about a new dangerous jellyfish.
Scientists still do not know how powerful the sting of Copula lucentia might be, and its minute size makes comparisons with much larger tropical box jellyfish particularly unhelpful.
For now, its stinging capability remains one of the questions researchers want to answer.
More than 200 found off El Campello
Scientists have now returned to the Costa Blanca coastline to find out more.
A new campaign involving the University of Alicante and Oceanogràfic in Valencia collected more than 200 specimens from waters around El Campello.
That gives researchers considerably more material to study than they had when first identifying the species.
Some of the jellyfish are now being kept at Oceanogràfic’s MedusaLab.
Because the creatures are so small, visitors need magnification to see them properly.
Researchers hope keeping the animals under controlled conditions will reveal something much more interesting than their appearance.
They want to see whether they can complete their reproductive cycle.
Scientists want to watch them grow up
The specimens collected during the latest campaign are still immature.
Miguel Candelas, who is responsible for jellyfish at Oceanogràfic, says one of the challenges will be getting them to reach sexual maturity and reproduce under controlled conditions.
Success could allow scientists to observe the animal’s life cycle for the first time.
That matters because identifying a species is only the beginning.
Researchers still have fundamental questions about Copula lucentia, including how it reproduces, what it eats and what eats it, how it fits into the wider marine food web and how its stinging cells behave.
They also do not yet know whether its apparent restriction to El Campello reflects its true distribution or simply the fact that nobody has found it elsewhere.
When your subject is almost transparent and can be smaller than a grain of rice, hide-and-seek comes with certain advantages.
The Mediterranean still has surprises
Perhaps the most interesting part of the discovery is where it happened.
The Mediterranean is hardly an unexplored ocean.
Its coastline has supported dense human populations for thousands of years, while generations of scientists have studied its marine ecosystems.
Yet researchers can still find animals that science has never formally described.
César Bordehore, a professor in the University of Alicante’s Department of Ecology and coordinator of its Marine Laboratory in Denia, says the discovery demonstrates how much Mediterranean biodiversity remains to be understood.
Bridging the Gap’s recap
- Scientists have identified a new jellyfish species in waters off El Campello.
- The species has been named Copula lucentia, referencing Lucentum and its connection with Alicante.
- It measures between one and seven millimetres and is almost transparent.
- Researchers collected the specimens at depths of less than 1.5 metres.
- Copula lucentia is only the second box jellyfish species documented in the Mediterranean.
- Scientists have so far documented it only in El Campello.
- A new research campaign collected more than 200 specimens.
- Some are now being studied at Oceanogràfic’s MedusaLab.
- Scientists still need to learn about its reproduction, ecological role and stinging capability.
- Researchers hope to complete its reproductive cycle under controlled conditions for the first time.
