Giant Ghost Jellyfish Filmed Off Argentina Coast: Rare Sighting

A massive giant phantom jellyfish, Stygiomedusa gigantea, glided across underwater cameras off Argentina’s coast, its enormous bell and trailing ribbon-like arms revealing just how immense these elusive deep-sea creatures can grow.

The specimen’s bell measured around one meter in diameter, comparable to the width of a standard dining table or a large beach umbrella, while its four oral arms extended far beyond the frame, capable of reaching over 10 meters in length, longer than a school bus or the height of a three-story building.

Unlike typical jellyfish with stinging tentacles, this species uses those paddle-shaped arms to envelop plankton and small fish, posing no threat to humans despite its daunting scale.

Researchers from the Schmidt Ocean Institute captured this rare footage during the Life in Extremes: Cold Seeps of Argentina expedition, which took place from December 2025 to January 2026 aboard the research vessel R/V Falkor (too). Led by Argentine chief scientist Dr. María Emilia Bravo, the team deployed the remotely operated vehicle SuBastian for deep-sea surveys along the continental shelf, spotting the jellyfish at an unusually shallow depth of 250 meters during a routine dive. The species, first scientifically described over a century ago with only about 130 documented sightings worldwide since, typically inhabits much deeper waters, making this encounter particularly noteworthy for the South Atlantic region.

Deep-sea jellyfish like Stygiomedusa gigantea showcase remarkable adaptations to their harsh environment, including pliant tissue that allows the bell to stretch four to five times its normal size for capturing scarce prey in the nutrient-poor abyss. Their spongy bodies withstand extreme pressures up to 40,000 kilopascals, equivalent to about 5,800 pounds per square inch, while a red-orange hue visible only in light helps them blend into the perpetual darkness of the midnight zone, appearing nearly invisible at depths up to 6,665 meters.

These creatures move with gentle pulsations, conserving energy in cold waters where metabolism slows, potentially enabling long lifespans though individual ages remain unknown due to the challenges of studying them in the wild.

This sighting joins a roster of other rare ocean giants that exemplify deep-sea gigantism, a phenomenon where creatures evolve massive sizes to cope with sparse food and vast distances. The colossal squid, for instance, stretches up to 14 meters, rivaling the length of a city bus, with eyes the size of dinner plates adapted for spotting prey in dim light.

Similarly, the giant isopod scuttles across the seafloor at up to 16 inches long, like an oversized pill bug built for scavenging whale falls, while the oarfish unfurls its ribbon-like body to eight meters or more, evoking ancient sea serpent myths in its eerie, elongated form.

Individual jellyfish ages remain unknown due to the challenges of studying them in the wild, though deep-sea species often exhibit slow metabolism and potentially long lifespans adapted to extreme conditions. The giant phantom’s ghostly, translucent appearance, pale pinkish hues pulsing gently for propulsion, has fueled its viral spread online, reminding viewers of the ocean’s vast unexplored realms.

Encounters like this, enabled by advanced ROV technology, highlight ongoing discoveries in marine biodiversity even in the 21st century.

These sightings carry broader significance as expeditions map sensitive deep-sea habitats facing emerging threats from climate change and resource interests. Open-sharing initiatives from groups like the Schmidt Ocean Institute democratize access to such wonders, fostering global appreciation for fragile ecosystems. For more on the species, explore the Monterey Bay Aquarium Research Institute’s detailed profile, the expedition overview, or the recent biodiversity findings.

References

1. Argentina’s Deep Sea Is More Biodiverse Than Scientists Thought – Schmidt Ocean Institute
2. Rare sighting of phantom jellyfish in deep sea off Argentina – BBC
3. Rare bus-sized phantom jellyfish caught on camera. See video. – USA Today
4. FirstpostNews: A rare phantom jellyfish has been spotted by scientists exploring the deep sea near Argentina. – Instagram
5. Stygiomedusa – Wikipedia
6. Giant phantom jelly – MBARI
7. The Deeper You Go, The More Giant Deep Sea Creatures Get – YouTube
8. Giant deep-sea beasts aren’t just the stuff of legend – here’s how they got so massive
9. Deep-sea gigantism – Wikipedia
10. Rare Deep-Sea Giant Phantom Jellyfish Sighting Is Recorded on Video – The New York Times