Watch: Massive Phantom Jellyfish Spotted In Rare Deep-Sea Footage

In a breathtaking deep-sea discovery, scientists recently spotted a rare phantom jellyfish the size of a school bus off the coast of Argentina. Known scientifically as Stygiomedusa gigantea, this massive jellyfish was captured on video, drifting 250 metres below the surface of the South Atlantic.

Scientists from the Schmidt Ocean Institute had been travelling along the entire length of the coastline from Buenos Aires to an offshore area near Tierra del Fuego, about 1,900 miles south, when they located the gelatinous giant.

Their bell can grow up to 1 m (3.3 ft) in diameter, and their four arms can reach up to 10 m (33 ft) long. They do not have any stinging tentacles, but use their arms to catch prey, including plankton and small fish.

"We were not expecting to see this level of biodiversity in the Argentine deep sea, and are so excited to see it teeming with life," said Dr Maria Emilia Bravo of the University of Buenos Aires, the expedition's chief scientist.

In the now-viral clip, captured via an autonomous submersible known as ROV SuBastian, the jellyfish can be seen contracting and extending its ribbon-like tendrils in the deep reaches of the ocean.

"Seeing all the biodiversity, ecosystem functions, and connectivity unfolding together was incredible. We opened a window into our country's biodiversity only to find there are so many more windows left to be opened," said Bravo.

Watch The Viral Clip Here:

ROV pilots filmed this giant phantom jelly, or Stygiomedusa gigantea, at 253 meters during an ROV descent to explore the Colorado-Rawson submarine canyon wall. #ArgentinianDeepSeeps pic.twitter.com/80tq5JYOTz

— Schmidt Ocean (@SchmidtOcean) January 2, 2026

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Ocean and Its Secrets

Apart from the jellyfish, the researchers also documented the largest known coral reef in the global ocean, with 28 suspected new species, including worms, corals, sea urchins, sea snails and sea anemones.

"We collected an unprecedented number of chemical, physical, and biological samples that will be used to understand connections in our waters for years to come," declared Dr Melisa Fernandez Severini of Instituto Argentino de Oceanografia and CONICET.

"These samples represent a unique opportunity to understand not only how extraordinary these extreme ecosystems are, but also how vulnerable they can be."