New Species Of Giant Single-Celled Organisms Discovered In The Deepest Regions Of The Pacific


Jack Dunhill

Social Media Coordinator and Staff Writer

clockJun 29 2020, 17:09 UTC
Newly discovered organisms  may help understand biodiversity on the seafloor.


The ocean is a massive place and exploring it all is a daunting task. With over 80 percent of the ocean unmapped, we’re discovering more and more new species that live in the very deepest regions.

In a collaborative effort between the National Oceanography Centre (NOC), the University of Hawai'i, and the University of Geneva, published in the European Journal of Protistology, four new species of large single-celled organisms have been discovered in the Clarion Clipperton Zone (CCZ) of the Pacific Ocean.


Separated into two new genera, these organisms are a type of xenophyophores that live on the ocean floor and form elaborate shell-like exoskeletons (called "tests") from the environment around them. Xenophyophores belong to the phylum Foraminifera, which is the most common organism found down in the "abyssal plains" of the CCZ.

The first new genus, named Moanammina after the Hawaiian word Moana, meaning "ocean", contains the new species Moanammina semicircularis, which builds a fan-like test that reaches around 7.5 centimeters (3 inches) high and sits on the ocean floor. The second genus containing two of the new species has been called Abyssalia, in homage to the murky depths the organisms are found in. The fourth species belongs to the Psammina genus, and has been called Psammina tenuis sp. Nov.

Left: An image of M. semicircularis on the seafloor. Right: An image of A. foliformis on the seafloor. Credit: Gooday et al., 2020 

"These four new species and two new genera have increased the number of described xenophyophores in the CCZ abyss to 17 (22 percent of the global total for this group), with many more known but still undescribed," said Andrew Gooday, professor at NOC and lead author of the findings, in a press release. "This part of the Pacific Ocean is clearly a hotspot of xenophyophore diversity."


Oceanographer Craig Smith, Chief Scientist on the RV Kilo Moana (which found the new organisms), said, "We see them everywhere on the seafloor in many different shapes and sizes. They clearly are very important members of the rich biological communities living in the CCZ. Among other things, they provide microhabitats and potential food sources for other organisms. We need to learn much more about the ecology these weird protozoans if we wish to fully understand how seafloor mining might impact these seafloor communities."

This study continues the work of characterizing xenophyophores and single-celled organisms in the CCZ area, with many more yet undiscovered. These results also demonstrate the first confirmation that abyssal xenophyophores have extremely long geographical ranges. Over 3,700 kilometers (2,300 miles away), another organism was found that is identical to the Moanammina semicircularis, suggesting these organisms are spread far and wide across the ocean.