The bright yellow worm that turns ocean poison into golden survival crystals

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.

Coauthor 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."

Dr. Wang says, "What makes this finding even more fascinating is that orpiment -- the same toxic, golden mineral produced by this worm -- was once prized by medieval and Renaissance painters. It's a curious convergence of biology and art history, unfolding in the depths of the ocean."

The authors note, "We were puzzled for a long time by the nature of the yellow intracellular granules, which had a vibrant color and nearly perfect spherical shape. It took us a combination of microscopy, spectroscopy, and Raman analysis to identify them as orpiment minerals -- a surprising finding."

The authors conclude, "We hope that this 'fighting poison with poison' model will encourage scientists to rethink how marine invertebrates interact with and possibly harness toxic elements in their environment."

Funding: This work was supported by grants from Natural Science Foundation of China (No. 42476133 to H.W.), Science and Technology Innovation Project of Laoshan Laboratory (Project Number No. LSKJ202203104 to H.W.), National Key RandD Program of China (Project Number 2018YFC0310702 to H.W.), Natural Science Foundation of China (Grant No. 42030407 to C.Li), and the NSFC Innovative Group Grant (No. 42221005 to M.X.W.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.