Rare sightings of giant phantom jellyfish — deep-sea creatures that look like UFO spaceships with thick ribbons streaming from their undersides — have been reported by cruise liner passengers who spotted the otherworldly animals off the coast of Antarctica, a new study publishedon Jan. 30 in the journal Polar Research shows.
The giant jellyfish, or Stygiomedusa gigantea, one of the deep sea's largest invertebrate predators, met the guests while they were riding in a submersible deployed by cruise line operator Viking in early 2022.
Researchers estimated that the jellyfish were longer than 16 feet, with one stretching to at least 33 feet in length, according to a study published Jan. 30 in the journal Polar Research.
Study first author Daniel Moore,a marine biologist and one of Viking's chief scientists, first realized guests had encountered the giant phantom when he saw a picture of one on a guest's camera. "I instantly recognized it for what it was and, given the rarity of sightings, was flooded with excitement," Moore told Live Science in an email.
冥河水母生活在除了北冰洋以外的所有海洋中。但由于這些神秘的生物通常在深海游蕩，人類幾乎看不到它們。
Giant Phantom jellyfish live in every ocean except for the Arctic Ocean. However, because these cryptic creatures typically swim deep below the surface, they are scarcely seen by humans.
The 2022 encounters with giant phantom jellyfish are already changing what we know about this mystical deep-water species, Moore adds—particularly the breadth of its ocean habitat. Phantom jellyfish are usually found at nearly 22,000 feet, but these animals were swimming in waters of between 260 and 900 feet.
Surprisingly, the first jellyfish sighting was not a one-off. Just a week later, in late January 2022, a different group of tourists also saw a phantom jellyfish, followed by one more, in mid-March. In the most recent tourist season, between October 2022 and January 2023, submersibles have spotted seven or eight more.
Scientists still know very little about these giant invertebrates, which dwell in the polar oceans' dark, cold midnight zone and are believed to use their undulating, ribbon-like arms to capture and prey on plankton and small fish.
The phantom jellyfish has been observed with a small fish—called a pelagic brotula, or Thalassobathiapelagica—living alongside it. In this mutually beneficial relationship, the fish receives shelter and protection in return for keeping the jellyfish disease-free by eating any parasites that attach to it.
As for why the large jellyfish are showing up in shallower Antarctic waters, Moore speculates they could be carried by currents, or perhaps come up from the depths to expose themselves to the sun to rid themselves of any additional parasites.
Antarctic waters below 160 feet haven’t yet been well explored because they are so difficult and expensive to reach. Now, with private submersibles descending to around a thousand feet, you might be “the first human ever to see a particular patch of seabed,” Moore says.
Personal submersibles are free-roaming vehicles that hold a pilot and six guests. They’re outfitted with probes and sophisticated cameras, allowing guests to take photos and video.
Such cruise expeditions are priced at tens of thousands of dollars a person, making them available to a very small group of individuals, says Paris Stefanoudis, a marine biologist at the University of Oxford. He says, “You have to face that fact: Not everyone can use [or afford] them.”
綜合來源：國家地理、Live Science網(wǎng)，央視網(wǎng)，Polar Research
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