A team of scientists were carrying out a major deep-sea expedition when they suddenly came across the freakishly long oceanic beast off Argentina in the South Atlantic
22:25, 04 Feb 2026Updated 22:25, 04 Feb 2026
You wouldn’t like to meet this while swimming in the sea, that’s for sure(Image: ROV SuBastian / Schmidt Ocean Institute)
A spooky-looking sea creature has been caught meandering its way through the murky depths off the coast of Argentina – with arms the length of a double-decker bus.
Scientists aboard the research vessel R/V Falkor (too), part of a major deep-sea expedition, were combing the South Atlantic seafloor when its cameras picked up something straight out of a sci-fi film: a rare phantom jellyfish, officially known as Stygiomedusa gigantea.
This animal’s four arms can stretch up to 10 metres long and its dome-like bell can measure about one metre across. The footage shows the beast at approximately 250 metres below the surface, with tiny fish darting around it.
The stunning sea beast was spotted by an expedition crew(Image: MBARI/Youtube)
Barely 100 sightings of this bizarre creature have even been recorded. And, unlike most other jellyfish, this particular species doesn’t possess stinging tentacles.
But the giant jellyfish wasn’t the only shock lurking in the deep. As the expedition moved from Buenos Aires towards Tierra del Fuego, the seabed exploded with life – from an enormous Bathelia candida coral reef to several additional reef complexes.
The creature uses its four massive arms to capture prey (Image: Antony Gilbert)
On top of this, scientists believe they may have stumbled across 28 completely unknown creatures. Schmidt Ocean Institute’s executive director, Dr Jyotika Virmani, said: “With every expedition to the deep sea, we find the ocean is full of life – as much as we see on land, and perhaps more because the Ocean contains 98% of the living space on this planet.”
While the expedition’s chief scientist, Dr. María Emilia Bravo of the University of Buenos Aires and CONICET said: “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. 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.”
The jellyfish’s tentacles aren’t venomous (Image: MBARI/Youtube)
In 2021, a separate group of scientists spotted another giant phantom jellyfish in the deep waters in California. Marine biologists from the Monterey Bay Aquarium Research Institute (MBARI) were searching the waters with a remote submarine when it came across the jellyfish at a depth of 3,200 feet.
The first specimen of the giant phantom jellyfish was collected way back in 1899. But it took scientists 60 years later to determine it was a unique new species of jellyfish and very little is still known about the invertebrate.
In a statement at the time, MBARI said: “Observations of Stygiomedusa gigantea (the giant phantom jellyfish) have helped illuminate its ecological role in the ocean’s depths. During an expedition to the Gulf of California, MBARI’s ROV Tiburon recorded a fish – the pelagic brotula (Thalassobathia pelagica)—alongside a giant phantom jelly.
“Researchers watched the brotula hover above the bell of its host and swim in and out of the jelly’s voluminous oral arms. The wide-open waters of the midnight zone offer little shelter, so many creatures find refuge in the gelatinous animals that are abundant in this environment.”
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