"Alien barnacle", "alien seabat""alien mine demon" ... the internet certainly loves an alleged extraterrestrial. And though we usually resist the pull of the unearthly, the force is just too strong in this deep-sea jelly. 

Image: NOAA/Okeanos Explorer

We give up. Let us take you to our leader, oh majestic sea saucer. 

This so-called "UFO jelly" (genus Atolla) was filmed at a depth of 1,260 metres by the team aboard the NOAA research vessel Okeanos Explorer. While this particular specimen was spotted off the coast of California, NOAA fisheries biologist Dr Mike Ford explains that the species is actually quite cosmopolitan. The animals have been seen in the Arctic, Antarctic, North Atlantic, Pacific, Gulf of Mexico and in the waters off the New Zealand coast.

"It appears to be Atolla wyvillei," he says, noting that the six members of the genus all possess a flat-disk umbrella, making identifying them from film quite tricky. To know for sure, we'd need to analyse the animal's lappets (the scalloped edges of the bell), overall size and arrangement of the stomach.  


Why would a deep-sea inhabitant sport such a vibrant skin tone? Red light is relatively weak, and therefore doesn't penetrate much of the ocean's depths. Because of this, red animals are near-invisible against their black backdrop. 

It's a play we've seen in many species, including one of our favourite invertebrates, the blood-belly comb jelly.

Like the comb jelly, Atolla jellies are known for their underwater light shows. "A. wyvillei will light up with an impressive display," says Ford. "The eight gonads arranged in a ring will light up, possibly as a defence mechanism."

This bioluminescent "burglar alarm" display, appearing as a circular flash of blue light (similar to that atop a police car), activates when the jelly is under threat – and it's a bit of a risky manoeuvre. Scientists suspect the light wards off hungry foes by luring in bigger predators such as squid – like a warning that says, "eat me and you'll soon be eaten yourself."

A team of NOAA biologists managed to film the light show back in 2004, during Operation Deep Scope. The first segment you see below shows the jelly in its natural habitat, illuminated by the lights of NOAA's submersible. Once back in the lab, however, the team got quite a different view. The jelly was placed in complete darkness, allowing the researchers to see its burglar alarm in action. 

So there you have it, folks. A deep-sea flying saucer with flashing gonads. Does it get much better? We think not.


Top header image: NOAA/Wikimedia Commons