Is the Giant Phantom Jellyfish Dangerous? Rare Sightings Put Facts and Size Compared to Humans in Focus

A rare deep sea video of a giant phantom jellyfish drifting through the dark waters off Argentina has stunned viewers and reignited questions about whether the elusive species poses any danger to humans.

Filmed around 820 feet (250 metres) below the surface during a scientific expedition led by Argentine researchers and supported by the Schmidt Ocean Institute, the footage shows the enormous jellyfish gliding through the blue, with small fish moving close to its ribbon-like arms.

The sheer scale of the animal and the rarity of such encounters have fuelled online fascination and unease in equal measure.

Rare Deep Sea Sighting Off Argentina

The sighting was recorded during an Argentinian-led research voyage that explored the length of the country's coastline, from Buenos Aires to waters off Tierra del Fuego. Using deep sea cameras, the team documented ecosystems rarely seen by humans. Among the discoveries were 28 suspected new ocean species and what scientists described as the largest known Bathelia candida coral reef in the global ocean, alongside several other reef complexes.

'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,' said Dr. Melisa Fernández Severini of Instituto Argentino de Oceanografía 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.'

The giant phantom jellyfish, known scientifically as Stygiomedusa gigantea, is seldom captured on video due to its deep sea habitat and the technical challenges of observing life at such depths. The footage released by the Schmidt Ocean Institute shows the jellyfish moving slowly, its bell rippling as long, pink arms trail behind it.

What Is the Giant Phantom Jellyfish?

Stygiomedusa gigantea is one of the largest known jellyfish species and among the most mysterious. Often referred to as the giant phantom jelly, it inhabits deep ocean waters where sunlight does not penetrate. Unlike more familiar jellyfish species found near the surface, this deep sea jellyfish is rarely encountered by researchers.

Scientists believe the species plays a role in deep ocean food webs, capturing prey such as small fish and plankton with its long, flowing arms. The species has been recorded only a handful of times on camera, making each confirmed sighting significant for marine science.

Is the Giant Phantom Jellyfish Dangerous to Humans?

Despite its intimidating appearance, researchers say the giant phantom jellyfish is not considered dangerous to humans. According to the Schmidt Ocean Institute, Stygiomedusa gigantea does not have stinging tentacles. Instead, it uses its arms to ensnare prey in the deep sea.

There is no evidence to suggest the species poses a threat to people. Encounters with humans are extremely unlikely given the depths at which the jellyfish lives. The fears sparked by the footage are largely driven by the animal's size and unfamiliar form rather than any documented risk.

Size Compared to Human: How Big Is It Really?

One of the most striking aspects of the footage is the jellyfish's apparent size compared to a human. The institute notes that giant phantom jellyfish can grow bells up to around 3.3 feet (1 metre) in diameter, with arms extending as long as 33 feet (10 metres). In visual terms, that makes the species comparable in length to a school bus when fully extended.

Assessing scale in deep sea video is difficult due to the lack of reference points. However, the presence of small fish swimming alongside the jellyfish offers some context for its enormous proportions. This size compared to human scale is a major reason the footage has resonated with audiences and driven searches for facts about the species.