A "Lost World" of weird white crabs and at least one gleaming, black-eyed octopus has been discovered in the Far South on the ocean floor near Antarctica, with dozens of species previously unknown to science thriving in a hot, pitch-dark ecosystem surrounding hydrothermal vents more than a mile-and-half beneath the surface.
Along with a unique variety of yeti crabs and what may be a novel octopus, the new critters include a predatory sea star with seven arms, plus various barnacles and sea anemones — all subsisting in a sunless world near vent systems along the East Scotia Ridge, located southeast of South America at a latitude comparable to the northern Gulf of Alaska.
An international team of 33 scientists used the remotely operated vehicle Isis and other survey devices to explore, sample and photograph the sites. The results, which suggest the area may contain life completely different from other known hydrothermal vents in the world's oceans, was published in this week's issue of the online journal PLoS Biology.
"Hydrothermal vents are home to animals found nowhere else on the planet that get their energy not from the Sun but from breaking down chemicals, such as hydrogen sulphide," explained lead scientist Alex Rogers of Oxford University, in a release about the research paper. "The first survey of these particular vents, in the Southern Ocean near Antarctica, has revealed a hot, dark, 'lost world' in which whole communities of previously unknown marine organisms thrive."
The Scotia Ridge vents were discovered in 2009 by cameras towed by the Royal Research Ship James Clark Ross. An expedition returned in 2010 with the Isis and explored the "black smokers" in detail for the first time. The most recent explorations took place only last winter during a six-week, 7,000-mile expedition aboard Royal Research Ship James Cook, part of a larger effort to investigate seafloor vents around the world.
The blog of the voyage contains 36 diary entries and photographs covering activities from Jan. 14 to Feb. 18, with visits to the Scotia Ridge vents beginning about Feb. 7. Here's a blog post from Feb. 12 describing the moment when the scientists discovered a completely new vent system.
The paper focused on the discoveries made at two particular sites, one about 8,500 feet down at about the same latitude as Anchorage, the other about 7,900 feet down a bit further north. In both areas, chimneys — what scientists call black smokers — rise 45 feet above the seabed and spew chemically rich water superheated up to 780 degrees F.
As the water spreads out, it cools into streams that range from about 40 degrees to 66 degrees, fueling a bizarre ecosystem with bacteria consuming chemicals at the bottom of the food chain and complex invertebrates like octopuses foraging at the top.
"Highlights from the ROV dives include images showing huge colonies of the new species of yeti crab, thought to dominate the Antarctic vent ecosystem, clustered around vent chimneys," a story about the paper explained. "Elsewhere the ROV spotted numbers of an undescribed predatory sea-star with seven arms crawling across fields of stalked barnacles. It also found an unidentified pale octopus, nearly 2,400 metres down, on the seafloor."
Rogers said they were as surprised by what they didn't find: None of the tubeworms, crabs and shrimps common to other deep-sea vents were present near Antarctica. That means the East Scotia Ridge vents may be unique on Earth, with the Southern Ocean somehow acting as a barrier to life from other areas.
"These findings are yet more evidence of the precious diversity to be found throughout the world's oceans," Rogers said in the story. "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."
Contact Doug O'Harra at doug(at)alaskadispatch.com