The alvinellid worm Paralvinella hessleri is the only animal that colonizes the hottest part of deep-sea hydrothermal vents in the west pacific. Wang et al. found P. hessleri accumulates exceptionally high level of toxic element arsenic (>1% of wet weight) and tolerates elevated concentrations of hydrogen sulfide. Using advanced microscopy, elementary analysis, and genomics and proteomics approaches, the authors identify a previously unrecognized arsenic-sulfide biomineralization process in P. hessleri. Their data suggest that arsenic accumulates within epithelial cell granules, where it likely reacts with sulfide diffused inward from the hydrothermal vent fluid, resulting in the intracellular formation of orpiment (As₂S₃) minerals. In this “fighting poison with poison” manner, the highly toxic arsenic and sulfide were simultaneously detoxified in the form of orpiment within intracellular granules of the single layer of epithelial cells. The image shows a lateral view of a P. hessleri specimen with buccal tentacles extroverted; note that the animal has a bright yellow color which derives from the epithelial orpiment crystals.

Image Credit: Hao Wang