Creature spotting NOAA Office of Ocean Exploration and Research, 2016 Deepwater Exploration of the Mariana

The discovery of mysterious lifeforms has stunned scientists during a series of dives into the Mariana trench — Earth’s deepest abyss.

“It’s just so exciting,” says Shirley Pomponi at the Harbor Branch Oceanographic Institution. “We’re finding new things every day.”

NOAA’s Okeanos research ship has been cruising the seas above the trench, which plunges 11 kilometres into the Pacific, since April. Researchers have been using sonar and a remotely operated vehicle to study the ocean there down to 6 kilometres.


Spectacular sea stars The control room on NOAA Ship Okeanos Explorer

“Every time we make a dive, we see something new. It’s mind-boggling,” says Patricia Fryer at the University of Hawaii.

She says the amount of new information being gathered is astounding, and many of the discoveries have stumped experts.

“They’re seeing fish which seem to be a cross-between an eel and a lizard fish,” says Fryer. “When they zoom in to look more closely they’re like ‘nope, that’s not like any of the ones we know’.”

Tube worms at the crater edge NOAA Office of Ocean Exploration and Research, 2016 Deepwater Exploration of the Mariana

The Mariana trench lies to the east of the Philippines, but like much of the deep sea floor it is understudied. “We know less about the 70 per cent of our planet covered by water than we do about Mars, Venus, the moon – even Jupiter,” says Fryer.

Live streaming of the dives has seen up to 40,000 people at a time tune-in to watch new discoveries as they happen, including scientists who comment on the finds.

Strange spheres NOAA Office of Ocean Exploration and Research, 2016 Deepwater Exploration of the Mariana

Despite this instant scientific expertise and the world wide web at their fingers, there have been several moments during the expedition when “the whole science party is dead silent because no one has any idea what we’re looking at”, wrote Diva Amon, of the University of Hawaii at Manoa, on the expedition’s blog recently.

Examples of such mysteries the deep sea has thrown at scientists during the first leg of the expedition include fields of fluffy and “strange little spheres” covering the sea floor (shown above) and in places forming mounds, “strange feathery, wispy things” attached to rocks (shown below), and “strange green stringy things” attached to corals.

“There was speculation that these are colonies of hydroids or bryozoans, but that isn’t saying much, as those are two totally different phyla (Cnidaria or Bryozoa),” wrote Amon about the wispy things. “To put that into context, it’s as bad as confusing a monkey (Chordata) with a cockroach (Arthropoda)!”

Strange feathery, wispy things NOAA Office of Ocean Exploration and Research, 2016 Deepwater Exploration of the Mariana

Cameras controlled from the surface have also picked up brand-new types of fish, coral and sponges. “Probably 90 per cent of what we’re seeing down there has simply not been witnessed before,” says Pomponi.

“We saw one jelly-like animal in the water column that is completely unknown. We didn’t even know what phylum it was in. That’s how unusual it was. It could be a jellyfish or a salp. We’re pretty sure it’s an animal, but that’s about it.”

Small spiral tracks similar to crop circles were also found buried in sediment. Later attributed to the little-known acorn worm, they were “extremely unusual and very, very rare”, says Fryer.

Acorn worm The control room on NOAA Ship Okeanos Explorer

A transparent ghost fish with gelatinous skin was also seen alive for the first time, swimming at more than 2.5 kilometres beneath the surface.

“Getting stumped helps all of us to understand why deep-sea science is important, justifies our continued interest in deep-sea exploration, and also highlights how exciting both exploration and research can be. New species also have the potential to result in discoveries with societal benefits in the form of new knowledge or products,” wrote Amon.

New species of slit shell? Strange feathery, wispy things

“More importantly though, it reminds us to remain humble, as there is still much to learn and appreciate about our deep ocean and the incredible planet we live on,” she wrote.

The expedition finished on 10 July, but Okeanos will be out once again on 17 July to study deep-sea habitats and seamounts within the Pacific Remote Islands Marine National Monument.

Read more: Ghostly deep sea octopus filmed at record depth of 4290 metres