A lost world of previously unknown creatures has been found flourishing next to boiling vents of water, miles under the surface of the Southern Ocean near Antarctica.
The discoveries, made by teams led by the University of Oxford and Southampton in collaboration with the British Antarctic Survey, include a new species of yeti crab, a forbidding pale octopus and a predatory seven-armed starfish.
The hydrothermal vents of the East Scotia Ridge are powered by underwater volcanoes, and produce springs of black, smoky water capable of reaching temperatures as high as 400C (752F). They are of interest to deep-sea biologists as they host animals found nowhere else that derive their energy not from sunlight but from the bacterial oxidation of chemicals in the vent fluids. These discoveries therefore help scientists to build a picture of what elements are actually required for life to exist.
The vents were discovered to be competing grounds for massive densities of crabs. Up to 600 of the crustaceans compete for each square metre of land, attempting to get as close as possible to the vents without accidentally cooking themselves in the scalding fissures.
The findings represent the latest in a string of discoveries of crab communities in the South Pacific since the first known yeti crab, the Kiwa hirsuta, was identified in 2005. However, the crabs were not only observed in much greater numbers in the East Scotia Ridge, but discovered to possess a unique physical trait. Whereas the hirsuta is characterised by the long, silky hairs that grow on its claws, thick clumps of hair cling to the undersides of the new species.
Nicolai Roterman, A DPhil student here at Oxford researching the genetic makeup of these creatures, was the mastermind behind a now infamous nickname for the new species. “I dubbed it the ‘Hoff Crab’ owing to its hairy chest”. He explains that the tufts “provide an ideal growing environment for bacteria which are then grazed upon by the crab – sort of using their own bodies as a farm”.
Roterman describes a gruelling work schedule on board the RSS James Cook, the team becoming accustomed to working 16-18 hour shifts over the course of the six weeks in order to make the most of an expensive opportunity. “Occasionally the volume of material found meant that some of us would be working for more than 30 hours straight before being relieved in order that everything was done correctly. This was imperative because you never know if the weather would suddenly deteriorate and potential science hours lost due to rough seas.” Resilience in testing conditions however proved worthwhile when breakthroughs were made – “I think all in all, we were delirious with excitement from the discoveries”.
During the expedition in January 2010, the team used a purpose-built, remotely operated vehicle called the Isis, boasting a HD video camera, a “slurp gun” for picking up delicate invertebrates and a sophisticated acoustic mapping system, to access the deep-sea vents. The ROV, about the size of a Land Rover, cost approximately £3 million to build and is capable of diving 6500m. Without the groundbreaking Isis, the team would not have been able to uncover and unearth some 12,000 samples of rocks, bacteria and other marine life.
The South Pacific is attractive to deep-sea biologists at the cutting-edge of research as it has been considered as an important gateway for the dispersal of vent animals between the other major oceans of the world over geological timescales. “We expected to find a mixture of animals probably reflecting such dispersal, certainly shrimp and possibly mussels and other animals”, says expedition leader and Professor of Conservation Biology Alex Rogers.However, the nature of the sea-life confronting the team surprised as much as it delighted. “We were fairly certain that the Southern Ocean was a major missing piece in our understanding of the distribution of vent species but we never expected something so new.” The Somerville Fellow adds, “what we didn’t find is almost as surprising as what we did. Many animals such as tubeworms, vent mussels, vent crabs, and vent shrimps, which are found in hydrothermal vents in the Pacific, Atlantic, and Indian Oceans, simply weren’t there.”
Prof. Rogers explains that the discoveries have significant implications in terms of an understanding of the marine life of the Indian Ocean, rewriting the story of vent biogeography. Just last month, more yeti crabs have been spotted by a research team following the lead of Rogers’ team, based at Southampton.
He hopes that the findings will encourage a new generation of marine biologists to involve themselves in deep-sea research. “With modern research vehicles the images we have are fantastic and really help to engender enthusiasm for the subject. For me, teaching students about the deep ocean is a pleasure. To reveal to anyone for the first time the wonders of the deep ocean and seeing their reactions is always great.”
A report detailing the research has been published in the open-access journal PLoS Biology.