Deep-Sea Researchers Spot a Mysterious Jellyfish Near The Mariana Trench

The glowing jellyfish was previously unknown to science

Jellyfish: April 24, 2016

As gelatinous blobs washed up on shore, jellyfish aren't particularly impressive. But in their natural, free-floating habitats they can seem like graceful spaceships drifting through the stars. Earlier this week, researchers exploring the depths of the Mariana Trench came across just such a graceful creature, but it turns out that this mysterious, glowing jellyfish had never been seen before.

Just four days ago, scientists aboard the National Oceanic and Atmospheric Administration (NOAA) research vessel Okeanos Explorer were surveying the waters near the Mariana Trench when they came across a jellyfish splayed out like a flying saucer. The red-and-yellow jellyfish appeared to be casting its tentacles out like a net to snag unsuspecting prey as it drifted in the ocean’s currents about 2.3 miles below the water’s surface near the Enigma Seamount, an underwater mountain range just west of the trench, Jennifer Frazer reports for Scientific American.

The researchers were taking their underwater remote-operated vehicle (ROV), Deep Discoverer out for a spin when they spotted the jelly. Judging by its brief stint on video, marine biologists say that it is likely a type of jellyfish called a “hydromedusa” belonging to the genus Crossota. While many jellyfish species go through a stationary polyp phase before growing into gooey, drifting blobs, Crossota jellies spend their whole lives floating freely through the ocean, George Dvorsky reports for Gizmodo.

According to the researchers, the still-unnamed jellyfish has two sets of tentacles—one short and one long. In the video taken by Deep Discoverer, you can see the jellyfish extending this outer set of tentacles in a predatory position as it tries to grab any unlucky prey that might swim into its clutches. The bright coloration inside its bell likely mark its gonads (which the scientists believe are the yellow markings), which are connected by the bright red radial canals stretching down its sides and may make up part of its digestive system, Sarah Laskow reports for Atlas Obscura.

This is far from the first new discovery made recently by the crew aboard the Okeanos Explorer. For several years, the research vessel and its ROV have plumbed the deepest depths of the ocean around the world, spotting new, unknown critters of all kinds as it maps the sea floor. On a recent dive, the Deep Discoverer robot discovered a previously unseen octopus that the public quickly nicknamed “Casper” thanks to its ghostly appearance.

The crew of the Okeanos Explorer is just over a week into their mission to explore the Mariana Trench, which is scheduled to last for the next several months. Already, they have spotted strange sights, including a field of giant, spherical amoebas and a so-called “Dumbo octopus” flitting by the deep-diving drone, Frazer writes.

If you want to watch along as the scientists explore the seafloor, there’s a handy livestream of their current expedition. Most of their dives begin at 4:30 P.M. Eastern Standard Time and end around 12:30 A.M., with replays of the night’s discoveries playing during the daylight hours.

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