But what are the mysterious species living under the earth’s crust, at the bottom of the oceans? Scientists, led in particular by Monika Bright, professor of marine biology at the University of Vienna, in Austria, have the answer: In particular, we find giant worms there! The results of this study, published Tuesday October 15 in the journal Naturereveal many other surprises…
Hydrothermal vents
These scientists have somehow lifted the stones sunk into the ocean floor, as anyone might do on a beach to discover crabs. Except they did at 2,515 m depthoff the coast of Central America, towards the East-Pacific ridge, where two tectonic plates move away from each otherunder an underwater mountain range.
This distance creates hydrothermal vents through which water, heated by magma and loaded with chemical compounds, escapes. We talk about“underwater oases”sincethey shelter a unique biodiversityunder a pressure 250 times greater than the surface and in complete darkness: mussels, giant tubeworms and bacteria producing nutrients from minerals.
These giant tubeworms build a tube in which they live: but how do the larvae travel? How do they manage to quickly colonize other oceanic regions? These would simply be carried with cold water from deep in the crust, water which mixes with the fluid from the chimneys before being expelled to the surface.
Oxygen and a temperature of 25°C!
It is thanks to a remote controlled underwater vehicle that these researchers were able, using manipulator arms, cameras and a large chisel, to drill and turn the rocks to collect samples, then discover the cavities. In addition to microbes, larvae and adult worms, limpets are found there. (molluscs), marine snails and polychaetes (a type of worm).
No one had previously thought to look for animals in the Earth’s crust, although the existence of these chimneys has only been known since the 1970s. In these 10 centimeter high caves, conditions close to the surface reign, conducive to the development of larvae. : 25°C, oxygen and toxic hydrogen sulfide but in moderate concentration.
It was there that was seen a glass 41 cm longand we better understand how the larvae disperse into the cavities to colonize the ocean floor. A sort of unexpected permanent fauna that must be preserved, particularly deep sea mining. This is a unique biodiversity, which has not yet revealed all its secrets…
Article references:
Giant worms swarm beneath the earth’s crust, in the deep ocean – Geo
Animal life in the shallow subseafloor crust at deep-sea hydrothermal vents – Nature
