The blind shrimp that likes hot water

First you need a submarine. One of these devices particularly dedicated to diving in the oceanic abyss. Then you need the experience of scientists who love adventure and risk-taking. The Frenchwoman Jozée Sarrazin belongs to this restricted circle of oceanauts. A researcher at Ifremer, she developed a passion for the strange fauna that lives around “hydrothermal” springs: located very deep on volcanic faults of the immense Atlantic ridge, these form small water geysers ultra hot. Enough to bring out real oases of life in this dark and cold universe.

Imagine Jozée Sarrazin’s surprise, during these long, exhausting dives, when she can observe, on the other side of her small porthole, “teeming swarms of several thousand individuals per square meter” of diaphanous shrimp. A crustacean of the abyss that does not stay still, taking advantage of the turbulence of the hot waters spewed from the depths of the Earth mixing with the cold waters, to breathe and feed. To this end, the animal has developed an astonishing symbiosis: its head is filled with filamentous bacteria which allow it to absorb, through chemosynthesis, nutrient elements essential to its development.

And in these great dark depths, the cycle of life also repeats itself. The reproduction period of these shrimps seems to be limited to the winter months and takes place on the outskirts of these geysers, where the males remain. The females then return near the hot water chimneys, allowing the eggs to become covered in an envelope of nourishing bacteria. Then, the young larvae disperse, carried away by the currents. A long and perilous solitary crossing awaits them. Before finding a little further, if all goes well, another oasis of life, hot water and collective life. We imagine the reunion party.