Bus-Sized Jellyfish Found Off Argentina in Deep-Sea Discovery

Imagine a jellyfish as long as a school bus, floating gracefully through the ocean's twilight zone. That's exactly what scientists discovered off Argentina's coast in December, and they could barely believe their eyes.

Marine biologist María Emilia Bravo and her team were exploring Argentina's deep waters when they spotted the massive creature using a remotely operated vehicle. The giant phantom jelly, measuring up to 33 feet long, drifted past their cameras at 820 feet below the surface.

"There was a mixture of excitement and disbelief," says Bravo, chief scientist of the expedition. "Its ethereal and delicate presence in such an extreme environment was deeply surprising."

These gentle giants are incredibly rare. Despite their enormous size, they've been spotted only about 120 times since 1899 because they prefer lurking in the ocean's midnight zone, where complete darkness reigns between 3,300 and 13,100 feet deep.

Unlike their stinging cousins, giant phantom jellies use ribbon-like arms to gently grab plankton and small fish, pulling meals toward their mouths. Their bells can stretch more than three feet wide, making them among the ocean's most impressive creatures.

The jellyfish sighting was just the beginning of the expedition's surprises. The team discovered Argentina's largest known Bathelia candida coral reef, nearly the size of Vatican City and located 370 miles farther south than scientists thought possible.

They also found Argentina's first documented deep-water whale fall, a whale carcass resting 12,800 feet below the surface. These remains become temporary restaurants and hotels for deep-sea animals, supporting entire ecosystems for decades as different creatures feast on and colonize the skeleton.

The Ripple Effect

The expedition documented 28 potential new species, including worms, sea urchins, corals, sea snails and anemones. The team also discovered active cold seeps, where chemicals like methane escape from the ocean floor and feed microbes that form the foundation of the entire marine food web.

"We were not expecting to see this level of biodiversity in the Argentine deep sea," Bravo says. The discoveries reveal thriving communities in waters previously thought to be relatively barren.

Thanks to underwater robots, scientists can now witness these mysterious creatures in their natural habitat for the first time. Marine biologist Steve Haddock notes that until recently, nobody could see the giant phantom jelly in its full glory where it actually lives.

Each new window into the deep sea reveals how much more remains unexplored beneath the waves.