MercoPress. South Atlantic News Agency

Argentine scientists film rare “giant phantom jelly” measuring about 11 meters in the South Atlantic

Researchers estimated the specimen’s total length at roughly 11 meters, a scale described in outreach terms as comparable to a school bus

An Argentine-led deep-sea expedition has recorded rare footage of Stygiomedusa gigantea—the so-called giant phantom jellyfish—in waters off Argentina, offering an unusual look at a species seldom observed alive in its natural environment. The animal was filmed at around 250 meters depth by the remotely operated vehicle SuBastian during the “Vida en los extremos” campaign aboard the research vessel R/V Falkor (too), involving scientists from CONICET and the University of Buenos Aires (UBA).

Researchers estimated the specimen’s total length at roughly 11 meters, a scale described in outreach terms as comparable to a school bus. Unlike many jellyfish, S. gigantea lacks stinging tentacles and instead uses four long oral arms to capture prey such as plankton and small fish—features that make the encounter visually striking when illuminated by deep-sea cameras.

¡GIGANTE DEL ABISMO!

Científicos del CONICET y la UBA registraron en video a la “medusa fantasma” en el Mar Argentino.
Mide 11 metros de largo (como un colectivo escolar) y fue hallada a 253 metros de profundidad. #Ciencia #CONICET #MarArgentino #MedusaFantasma pic.twitter.com/MF3AdnfCY0

— Aconcagua Radio (@Aconcagua_radio) February 5, 2026

“We were not expecting to see this level of biodiversity in the Argentine deep sea,” said expedition chief scientist María Emilia Bravo (UBA–CONICET), referring to the broader set of observations made along the continental margin. The mission’s summary also reported 28 organisms suspected to be new species, alongside extensive coral and seep habitats documented across multiple dive sites.

Beyond the jellyfish footage, the expedition reported what it described as the largest known Bathelia candida coral reef and the country’s first documented deep-water whale fall, an event where a carcass becomes a localized food source that can sustain deep-sea communities for extended periods.