Découverte de nouvelles espèces près de sources hydrothermales dans les profondeurs des mers de l'Antarctique
Parmi ces nouvelles espèces situées vers les moins 2300 m de profondeur !, l’on peut voir des crabes yéti, des anémones de mer, des escargots de mer et des étoiles de mer à sept branches…
©L’excellent article scientifique d’origine sur : http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001234:
A lost world of animal life has been discovered on the Antarctic sea floor, after an aquatic robot found various new species clustered around hydrothermal vents.
These vents are fissures in the Earth's surface, which spew out water rich in chemicals and heated to boiling temperatures by the interior of the planet. Hydrothermal vents are home to animals found nowhere else because they get energy by breaking down those chemicals, instead of from the Sun.
Researchers led by the universities of Oxford and Southampton, the National Oceanography Centre, and British Antarctic Survey have been able to explore the East Scotia Ridge deep beneath the Southern Ocean, for the first time, with a Remotely Operated Vehicle (ROV).
They found black smokers -- a type of vent that can reach temperatures up to 382 degrees Celsius and spits out chemicals like hydrogen sulphide. Here the team found "a hot, dark, lost world," said research leader Alex Rogers of Oxford University's Department of Zoology, "in which whole communities of previously unknown marine organisms thrive."
Around these vents they found various new species. They discovered an undescribed predatory seastar with seven arms, which crawls across fields of stalked barnacles. Nearly 2,400 metres down on the seafloor they found an unidentified octopus that's so pale it's almost completely colourless.
They also found another new type of Yeti crab. This furry crustacean family was first discovered in the South Pacific Ocean in 2005, and another species -- one that maintains a farm of bacteria on its claws, feeding the microscopic critters by waving its arms over sulfide vents -- was described in 2011.
This new crab lives in massive colonies, clustering in a crowd of tiny crabs around the vents. These ones have long setae (hair-like structures) on their undersides. According to BBC News, this hairy-chested characteristic earned it a nickname: the "Hasselhoff crab".
"What we didn't find is almost as surprising as what we did," said Rogers. "Many animals such as tubeworms, vent mussels, vent crabs, and vent shrimps, found in hydrothermal vents in the Pacific, Atlantic, and Indian Oceans, simply weren't there."
This suggests that the Southern Ocean may act as a barrier to some of these typical vent animals, and shows that individual vent ecosystems may be much more diverse than previously thought.
"Everywhere we look, whether it is in the sunlit coral reefs of tropical waters or these Antarctic vents shrouded in eternal darkness, we find unique ecosystems that we need to understand and protect," said Rogers.
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