Hundreds of meters below the ocean surface, hydrothermal vents attract life. Shrimp, crabs, worms and even mussels have already been observed there. They feed on nutrientsnutrients produced by the mixing of seawater with magma. Science also knows that at the heart of these hydrothermal vents, beneath the surface of floorfloor oceanic, live a good number of microbesmicrobes. And researchers on board the research vessel Falkor (too) of the Schmidt Ocean Institute (United States) recently made a discovery there that stunned them.
Did you know?
Hydrothermal vents are like doors opening onto the seabed. The place where tectonic plates meet and ocean water mixes with magma coming from beneath the ocean crust.
They had already discussed their unexpected discovery a few months ago. It is now confirmed. In the magazine Nature Communicationsthey first tell why they sent the remote-controlled vehicle SuBastian to a depth of 2,500 meters. Their objective was to explore the East Pacific Ridge, a particularly active volcanic ridge. For what purpose? To collect samples of the rock that constitutes the hydrothermal vent. Samples in which they hoped to find larvae of tube worms and thus understand a little better how the latter settle in environments that are a priori so hostile (without lightlight of soleilsoleil and with a pressionpression overwhelming).
Cavities beneath the oceanic crust filled with life
The robotrobot encountered difficulty in breaking the chimneychimney hydrothermal into small pieces. But beneath the plates of oceanic crust that it lifted, researchers discovered cavities about ten centimeters deep filled with hydrothermal fluid. Enough to bring the interior temperature to a pleasant 25°C. But so far, nothing very surprising. Because the geologistsgeologists knew of their existence.
It was on closer inspection that the researchers were surprised. The images sent back by their remote-controlled vehicle showed an entire population that no one would have imagined finding there. Snails and mussels. But also, giant tube worms (Riftia pachyptila))also called giant bearded worms. The species can reach up to three meters in length.
On the importance of protecting the seabed about which we know too little
What is surprising is not finding forms of life beneath the surface of the TerreTerre. Biologists know that probably even 70% of all microbes on our planet are hidden under the surface. earth’s crustearth’s crust. Yet never before had they imagined observing such ecosystemsecosystems complexes under the seabed.
But then, how did these animals get there? The researchers suggest that larvae that live on the ocean floor (the ones they were studying) could move underground in the fluids of hydrothermal vents. Thus, the ecosystems of the ocean, seafloor and subsurface ocean would be deeply connected in a dynamic relationship.
What now seems obvious is that there is a “layer of biomassbiomass » under the bottom of the oceans of which everything, or almost everything, still remains to be understood. Knowing that this newly discovered layer is already threatened by deep-water mining projects. Scientists are therefore calling for protective measures. Especially since better understanding what is happening there could also shed light on our search for life elsewhere in the Solar System. In Europe, for example, the lunelune of JupiterJupiter towards which the probe of the NasaNasaEuropa Clipper. It indeed presents volcanic activity and an ocean, conditions which could be comparable to those encountered around terrestrial hydrothermal vents.
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