The worm, named Paralvinella hessleri, is the only animal to inhabit the hottest part of deep sea hydrothermal vents in the west Pacific, where hot, mineral-rich water spews from the seafloor. These fluids can contain high levels of sulfide, as well as arsenic, which builds up in the tissues of P. hessleri, sometimes making up more than 1% of the worm's body weight.

Li and his team investigated how P. hessleri can tolerate the high levels of arsenic and sulfide in the vent fluids. They used advanced microscopy, and DNA, protein and chemical analyses to identify a previously unknown detoxification process. The worm accumulates particles of arsenic in its skin cells, which then react with sulfide from the hydrothermal vent fluids to form small clumps of a yellow mineral called orpiment.

The study provides new insights into the novel detoxification strategy that P. hessleri uses for "fighting poison with poison," which enables it to live in an extremely toxic environment. Previous studies have found that related worms living in other parts of the world, as well as some snail species in the West Pacific, also accumulate high levels of arsenic, and may use this same strategy.

Co-author Dr. Hao Wang adds, "This was my first deep-sea expedition, and I was stunned by what I saw on the ROV monitor—the bright yellow Paralvinella hessleri worms were unlike anything I had ever seen, standing out vividly against the white biofilm and dark hydrothermal vent landscape. It was hard to believe that any animal could survive, let alone thrive, in such an extreme and toxic environment."