An international team of researchers has literally uncovered animal life thriving beneath sections of the seafloor in the middle of the Pacific Ocean.
While microbes and viruses have been found in similar subseafloor habitats, this study demonstrates that larger animals can live there, too.
The researchers focused on the East Pacific Rise, a volcanically active ridge on the floor of the Pacific where two tectonic plates are diverging. The team travelled aboard the Schmidt Ocean Institute research vessel Falkor (too).
Located at a depth of 2,515m (2750 yds), the ridge sports many hydrothermal vents, which are openings in the seafloor where ocean water is heated by magma beneath the Earth’s crust.
Hydrothermal vents support diverse ecosystems and some scientists hypothesise that these deep-sea vents may be where life on Earth originated.
Using a remotely operated vehicle named SuB-astian, the researchers lifted lava rock shelves near the vents to reveal shallow cavities of warm water under the seafloor.
Photos from SuB-astian revealed colonies of giant tubeworms, snails and mussels living in communities within the cavities.
Most of the subseafloor animals belong to species that also live on the seafloor surface. This finding strongly suggests the two ecosystems are connected.
The researchers hypothesise that tiny larvae from the surface ecosystem drop through the porous volcanic rocks to populate the cavity ecosystem below.
Since many of these animals host dense bacterial communities that oxidize chemicals and fix nitrogen, knowledge of their expanded habitat could improve computer models of these chemicals.
The researchers also argue for protection of the subseafloor ecosystems from human impacts like deep-sea mining, especially as the extent and diversity of these ecosystems is not fully described.
The findings are published in Nature Communications today.
The Ultramarine project – focussing on research and innovation in our marine environments – is supported by Minderoo Foundation.