Scientists caught rare footage of sea cucumbers hovering deep in the Gulf of Mexico — and it looks like something from an alien world

One of the “dancing sea cucumbers” that fascinated the researchers.

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One of the “dancing sea cucumbers” that fascinated the researchers.
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Image courtesy of the NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2018

Scientists from the National Oceanic and Atmospheric Administration are conducting an expedition to explore uncharted waters in the deepest parts of the Gulf of Mexico – and they caught some surprising footage of sea cucumbers hovering in the depths.

Most sea cucumbers, or holothuroids in scientific terms, spend their lives feeding on seafloor sediment. But scientists now believe a few species are actually capable of regulating their buoyancy to hover above the seafloor within the water column.

The NOAA scientists captured stunning footage of this during their three-week-long expedition in the Gulf of Mexico on the research ship Okeanos Explorer. The researchers used a remotely piloted submersible to watch the sea cucumbers, and were thrilled to capture the creatures’ locomotion on one of their dives.

“It looks like he’s doing a ballet – a ballet dance,” one of the researchers said as he viewed the footage. “You don’t see that view every day.”

The sea cucumbers’ hovering is similar to how a scuba diver uses his lungs and air tank to maintain a level path underwater.

One particular genus of sea cucumber, the benthothuria, propels itself around the seafloor in an even weirder fashion: it thrusts itself off the sediment by flexing its body, then defecates to shed ballast, and slowly sinks back toward the bottom, according to NOAA.

The scientists also encountered a kind of sea cucumber called enypniastes, which looks so bizarre they dubbed it the “headless chicken monster.” The cucumber uses its hovering ability to stay just above the sediment, and uses tentacle-like appendages to shove detritus into its mouth.

Scientists still don’t fully understand how sea cucumbers regulate their buoyancy. They conducted experiments on some specimens and found that the animals ingest mud to regulate their density. But there are many questions left to answer.

The hovering sea cucumbers are yet another example of the stunning footage NOAA scientists have captured and put online as part of this year’s Okeanos Explorer expedition. With their submersibles, they’ve also uncovered never-before-seen shipwrecks and filmed a rare battle between two octopuses on the seafloor. They dubbed that video “Kraken Attack.”

You can watch the full NOAA video of the sea cucumbers hovering and swimming here, or watch sped-up footage of a sea cucumber using its tentacles to feed.