A box jellyfish measuring between one and seven millimetres across has been described from the waters off Alicante, and it is only the second of its kind recorded in the Mediterranean.
The animal, Copula lucentia, was formally described in 2024 by a team from the University of Alicante working at the university's Marine Laboratory in Dénia, part of the Ramón Margalef Multidisciplinary Institute for Environmental Research. The description appeared in the journal Marine Biodiversity and combined morphological and genetic analysis with contributions from specialists in other countries. The university set out the work in a release carried by Phys.org.
The specimens on which the description rests were collected between 2016 and 2018 off El Campello, north of Alicante. The species has so far been recorded nowhere else.
Its name refers to Lucentum, the Latin name for Alicante.
Copula lucentia is a cubozoan: its bell is cube-shaped rather than domed. It is almost transparent, carries four tentacles and bears small adhesive structures. It lives in water less than 1.5 metres deep, over rocky and sandy seabeds and among seagrass meadows. Its nearest described relative, Copula sivickisi, is found elsewhere.
Until this description, the Mediterranean had one documented box jellyfish, Carybdea marsupialis, described by Linnaeus in 1758.
Eva Fonfría, the University of Alicante researcher who led the study, said: "Finding a new species in the Mediterranean, where everything is so heavily studied, is very important."
César Bordehore, a senior lecturer in the university's department of ecology and coordinator of the Dénia laboratory, described the find as a milestone for marine research.
Work on the animal has continued since. About eight years after the original collections, a sampling campaign run with the Oceanogràfic in Valencia gathered more than 200 specimens. Some are held in the aquarium's Medusa Lab, where researchers are attempting to raise them to maturity and complete the life cycle in captivity.
Miguel Candelas, a biologist and head of jellyfish at the Oceanogràfic, said: "This is a challenge for us because it is the first time this species has been kept in an aquarium."
Bordehore's team also coordinates Sea4Future, a Horizon Europe project with 22 partners in 12 countries, which aims to help restore Mediterranean fish stocks and protect turtles, dolphins and whales.
The significance claimed for the find is worth restating precisely, because it carries an arithmetic the researchers did not perform. The Mediterranean's first box jellyfish was described in 1758. Its second was described in 2024.
That is an interval of 266 years, and it is the entire data set. The sea has produced two box jellyfish species in two and a half centuries, which gives a rate of one every 266 years.
The Department of Unnecessary Research has applied the rate forward. The third Mediterranean box jellyfish is due in 2290.
The description of this sea as heavily studied can meanwhile be tested against the specimen. It is at most seven millimetres long, almost transparent, and lives in less than a metre and a half of water at a single beach, which is where people stand.
Our analysts therefore accept that the Mediterranean has been exhaustively surveyed, with one qualification. It appears to have been surveyed everywhere except the shallow end.