Bus-sized Jellyfish discovered off Argentina in rare deep-sea sighting

Rare sighting of Giant phantom jellyfish discovered in Argentina. (Image: Schmidt Ocean Institute/ROV SuBastian)

• Giant phantom jellyfish filmed by scientists off Argentina's coast in deep waters.
• The jellyfish's arms can reach 10 metres, making it as long as a school bus.
• Under 120 sightings of this rare species recorded in the past century.

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The deep ocean has revealed another surprise. Scientists have spotted a massive jellyfish near Argentina. Its size shocked even experienced researchers. The rare creature was filmed in dark waters. It appeared drifting silently in the deep sea. Experts say sightings like this are extremely uncommon. Very few humans have ever seen this species alive. The discovery offers a rare window into ocean life.

What Jellyfish species were Discovered?

The creature is known as the giant phantom jellyfish. Its scientific name is Stygiomedusa gigantea. It is one of the largest jellyfish species on Earth. Its bell can grow over one metre wide. Its long, ribbon-like arms can stretch nearly 10 metres.

This makes it comparable to the length of a school bus. Unlike many jellyfish, it has no stinging tentacles. Instead, it uses its arms to trap prey. It feeds mainly on plankton and small fish.

Who Made the Discovery?

The jellyfish was recorded by marine scientists. They were part of a deep-sea research expedition. The mission took place in the South Atlantic Ocean. The team was supported by the Schmidt Ocean Institute.

Scientists found a jellyfish that can grow as big as a school bus off Argentina's coast!

On a deep-sea expedition led by @SchmidtOcean, researchers saw a rare phantom jellyfish, which has arms that can be over 30 feet long. See more of their findings: https://t.co/bAuIFNQSj3pic.twitter.com/HcKJ7Didg3 — Oceana (@oceana) February 4, 2026

They used an advanced remotely operated vehicle (ROV). The ROV is called SuBastian. It allows scientists to explore extreme depths. It carries high-resolution cameras and sensors. This technology made the rare sighting possible.

How "bus-sized" Jellyfish was Found?

The jellyfish was spotted off Argentina’s continental shelf. The area lies between Buenos Aires and Tierra del Fuego. It is part of a poorly explored deep-sea region. The creature was found hundreds of metres below the surface.

Sunlight does not reach this depth. Temperatures remain cold and constant. The ROV captured clear video footage. Scientists later confirmed the species. They described the encounter as extraordinary.

ROV SuBastian who captured the bus sized jellyfish. (Image: Schmidt Ocean Institute)

Why Is This Jellyfish So Rare?

Giant phantom jellyfish live in the “midnight zone.” This region is extremely difficult to study. Only special equipment can reach it. Over the past century, fewer than 120 sightings exist.

Most were brief and unclear, but few were properly recorded. These jellyfish move slowly and silently. They rarely interact with research vehicles. This makes encounters very uncommon.

Bus-Sized Jellyfish Amazed Scientists

The discovery left marine researchers stunned. Few expected to see such a massive creature alive. It moved slowly and gracefully through the water. This allowed cameras to capture rare close-up views. Experts called the moment “extraordinary.”

They said it was a once-in-a-career sighting. The footage will help future deep-sea studies. The encounter proved that giant life forms still exist in unexplored ocean regions. It reminded scientists how much remains undiscovered.