Discoveries of species and genera have been made in the Clarion-Clipperton Zone (CCZ) lining the Pacific Ocean. The region is considered a "gold mine" for treasured metals and rare earth minerals deposited in polymetallic nodules found along the ocean floor.
Now, scientists add four new species and genera of xenophyophores to the list of other species discovered along the CCZ abyss. According to Andrew Gooday, a marine ecologist from the National Oceanography Center in the UK, the Pacific Ocean's specific region is undoubtedly a hotspot of xenophyophore diversity.
One of the discoveries is the new genus Abyssalia. It got its name from the abyss in which it dwells. In an expedition in 2018, aboard the RV Kilo Moana in the western CCZ, the researchers found two Abyssalia species, namely A. sphaerica and A. foliformis.
The full findings of the discovery were reported in the European Journal of Protistology.
What are Xenophyophores?
Xenophyophores are a clade of giant, single-celled protozoans. They are part of the class foraminifera.
The protozoans are one of the most prevalent types of large life-forms found along the CCZ abyssal expanse. Although they've been described since the late 19th century, not much is known about them. This may be mainly due to the extreme depths at which they lurk.
Xenophyophores have shells made up of tiny particles glued together. These shells are called tests. In the case of Abyssalia, its shells are made from a homogeneous net of sponge spicules with no distinct surface layer.
It remains unclear about what xenophyophores eat. However, a paper from 2004 may have given clues on the protozoan's diet. The research paper particularly studied the xenophyophore Syringammina corbicula.
In the study, the xenophyophores were found enriched in triacylglycerols. Triacylglycerols are energy storage lipids in animals. They also contained a higher level of bacterial fatty acids than those in reference to sediment. Their study depicted that bacteria were abundantly present on S. corbicula.
New Discoveries of Species and Genera
A. sphaerica, which is spherical in shape, somewhat resembles a dandelion, while A. foliformis takes on a flatter, leaf-like shape.
The other new genus identified, Moanammina, got its name from Moana, which means "ocean" in Hawaiian, Maori, and Polynesian dialects.
Moanammina semicircularis has a stalked test that resembles a leaf. On the other hand, the other new species belonging to the genus Psammina, called Psammina tenuis, has a delicate, thin, plate-like test.
The researchers also uncovered what they suggest could be a novel xenophyophore in a round 'mudball' shape. However, its mudball-like composition, unfortunately, disintegrated before a comprehensive examination could validate its identity.
According to Craig Smith, an oceanographer from the University of Hawai'i Mānoa, xenophyophores can be found lavishly on the seabed in various shapes and sizes. The chief scientist on the RV Kilo Moana cruise adds that the creatures are clearly vital members of the wealthy biological communities living in the CCZ.
Among other things, he says the protozoans also provide microhabitats and probable food sources for other organisms. He believes that more studies on the creatures need to be conducted to fully understand how seafloor mining might impact their communities.
