British scientists have found a remarkable array of creatures, some of them new to science, in one of the most inhospitable regions of the deep sea. In the first ever expedition to explore and take samples from the "Dragon Vent" in the south-west Indian Ocean, remotely operated submarines spotted yeti crabs, sea cucumbers and snails living around the boiling column of mineral-rich water that spews out of the seafloor.
Dr Jon Copley, a marine biologist at the University of Southampton who led the exploration of the Dragon Vent, said his team found animals that had not been seen in neighbouring parts of the oceans.
"We found a new type of yeti crab. Yeti crabs are known at vents in the eastern Pacific and there are two species described so far, but they have very long, hairy arms – ours have short arms and their undersides are covered in bristles. They're quite different to the ones that are known from the Pacific," said Copley. "This is the first time a Yeti crab has been seen in the Indian Ocean."
His team also found sea cucumbers, vent shrimps and scaly-foot snails. Sea cucumbers have previously only been seen at deep sea vents in the eastern Pacific. "This is the first time they've been seen at vents in the Indian Ocean and they're not known from the central Indian or mid-Atlantic vents so far," he said.
Deep-sea vents, also known as hydrothermal vents, are springs of superheated water that are powered by underwater volcanoes. They erupt from the sea bed and are usually found a few miles under the sea surface. The scalding temperatures and rich mineral content of the water give rise to vast rocky chimneys, which have been found to support a wide variety of life forms.
The survey was part of a larger expedition to study underwater mountains aboard the RRS James Cook, which sailed from Cape Town on 7 November and returned to South Africa on 21 December. The exploration of the Dragon Vent took place in an intense three-day burst in the middle of the trip.
Copley's team took hundreds of samples of 17 different creatures, all of which are now being shipped back to his lab for detailed morphological and genetic examination. "Chances are that there will be several that are new species," he said. "We won't know for sure until we get them back into the lab and analyse them."
Copley's work builds on a Chinese expedition in 2007 that pinpointed the hydrothermal vents on the southwest Indian ridge for the first time. This chain of undersea volcanoes joins the mid-Atlantic ridge to the central Indian ridge. This part of the volcanic ridge is less volcanically active, so scientists think hydrothermal vents should be fewer and more scattered here. It therefore raises the question of whether life there is significantly different.
Copley said that characterising the life at the world's hydrothermal vents was a race against time. "Earlier this year, China was granted a licence by the UN International Seabed Authority for exploratory mining at deep-sea vents on the southwest Indian ridge," he said. "The vent chimneys are very rich in copper, zinc, gold and uranium. But we have no idea what's actually living there."
In evolutionary terms, hydrothermal vents were like the islands of the ocean floor, he added. "Just like the 19th century naturalists used to go to the Galápagos and other islands to find species there that are different to elsewhere and then use that to understand patterns of dispersal of dispersal and evolution, we can use deep-sea vents to do the same things beneath the waves," he said.
"And we need to do that because the exploitation of the deep ocean is overtaking its exploration. We're fishing in deeper and deeper waters, oil and gas is moving into deeper waters and now there's mining starting to take place in deep waters. We need to understand how species disperse and evolve in the deep oceans if we're going to make responsible decisions about managing their resources."
