Watch This Giant Phantom Jellyfish With 33-Foot-Long Arms Float Through the Deep Ocean

One of the largest jellyfish in the world, the giant phantom jellyfish (Stygiomedusa gigantea), was captured on film lurking in the depths of Monterey Bay, California, reports Ben Turner for Live Science. In the footage captured by marine biologists piloting a remote submarine, the scarlet jellyfish is seen bobbing along with its bell-shaped head and four long, flowing arms that resemble a kite's ribbon tails.

Giant phantom jellies truly live up to their name: The creature's bell can be up to three feet wide, and its arms reach lengths of 33 feet. Although they are quite big, they're actually rather hard to find. Since it was first discovered by scientists in 1899, the highly elusive creature has only been observed about 100 times in total, per Live Science. Despite completing thousands of dives, Monterey Bay Aquarium Research Institute (MBARI) scientists have documented the species about nine times in the wild.

An extraordinary deep-sea sighting: The giant phantom jelly

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One reason these deep sea creatures are hard to find is that they lurk 21,900 feet below the surface. This depth of the ocean is called the midnight, or bathypelagic zone, where sunlight does not penetrate, reports Brian Kahn for Gizmodo. Other species of jellyfish, angler fish, cuttlefish, and giant squid are also found in the midnight zone. Water pressure reaches up to 5,800 pounds per square inch at these depths, but jellies can survive these tremendous pressures because their soft gelatinous bodies absorb them.

Observing sea life in their natural habitat at these depths is made possible using ROVs and has allowed experts to learn more about jellies. While trawling nets are occassionally used to capture other kinds of deep-sea life for research, it is not ideal for studying jellyfish, Live Science reports.

"These nets can be useful for researching robust creatures like fish, crustaceans, and squids," MBARI tells Live Science. "But jellies disintegrate into gelatinous goo in trawl nets."

MBARI's remote-operated vehicle (ROV) dubbed Tiburon filmed this giant phantom jellyfish about 3,200 feet below the surface, reports Grace Ebert for Colossal. In the video, the giant jellyfish's large bell is seen pulsing and glowing a faint orange as it floats in the dark abyss. 

While much is unknown about the giant phantom, researchers suspect it uses its long, drape-like, "oral arms" to tangle up prey and bring it up to its mouth, Colossal reports. MBARI scientists also observed pelagic brotula (Thalassobathia pelagica) darting in and around the jellyfish's flowing body, a statement explains. Despite such close proximity to the jelly's mouth, some creatures may hide among its tentacles and large billowing head for safety in the open waters of the midnight zone. 

Elizabeth Gamillo | | READ MORE

Elizabeth Gamillo is a correspondent for Smithsonian and a science journalist based in Milwaukee, Wisconsin. She has written for Science magazine as their 2018 AAAS Diverse Voices in Science Journalism Intern.