Deep-Sea Worm Produces Orpiment, a Toxic Yellow Pigment Utilized in Historic Artwork

This Deep-Sea Worm Creates a Toxic Yellow Pigment Found in Rembrandt and Cézanne Paintings

By Mohana Basu & Nature journal

A bright-yellow worm that lives in deep-sea hydrothermal vents is the primary recognized animal to create orpiment, an excellent however poisonous mineral utilized by artists from antiquity till the nineteenth century. The findings have been revealed in PLoS Biology this week.

The worm (Paralvinella hessleri) is the one creature to inhabit the most well liked a part of deep-sea hydrothermal vents within the Okinawa Trough within the western Pacific Ocean. The scorching, mineral-rich water that shoots up from the ocean ground comprises excessive ranges of poisonous sulfide and arsenic.

Researchers discovered that the worm accumulates microscopic particles of arsenic on its outer pores and skin cells in addition to alongside its inner organs. This reacts with sulfide from the hydrothermal vent to kind small clumps of orpiment, fashioning a microscopic armour across the worm that protects it from the poisonous atmosphere.

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Orpiment is a naturally occurring arsenic sulfide mineral, typically present in hydrothermal and magmatic ore deposits.

The findings got here as a shock to the analysis group. In the deep sea, creatures dwell in complete darkness and are usually grey-ish white or adorned in hues of orange to darkish purple, says co-author Hao Wang, a deep-sea biologist on the Chinese Academy of Sciences in Qingdao. It “doesn’t make any sense to make pigment in total darkness,” Wang says.

Unknown mechanism

The staff is but to find how arsenic is transported into the creature’s inner organs.

Other deep-sea creatures are recognized to supply minerals as a protecting armour. The scaly-foot snail (Chrysomallon squamiferum) as an illustration, hosts micro organism that detoxifies sulfide by way of the extracellular biomineralization of iron sulfides in its scales, says Narissa Bax, a marine scientist at Greenland Institute of Natural Resources in Nuuk.

“Paralvinella hessleri may intentionally combine toxins into a single, ‘safe’, crystalline mineral within its own cells,” she says. It’s potential to combat poison with poison on this method is exceptional, she provides.

But additional analysis to verify how this happens might be difficult, owing to the acute circumstances in deep-sea vents, and difficulties learning such species outdoors their pure environments, she says. Cultivation of P. hessleri in a laboratory setting is at present not potential.

This article is reproduced with permission and was first published on August 28, 2025.

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