Orpiment is a bright golden pigment adored by Renaissance painters. It also happens to be deeply toxic.
Despite its toxicity, the substance is key to the survival of a particularly hardy species of deep sea worm, enabling it to counteract the noxious chemicals that persist in its habitat – effectively allowing the critter to fight poison with poison.
“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,” the authors stated in the study that was recently published in PLOS Biology.
A Golden, Deep Sea Worm
Unlike the vast majority of deep sea dwellers that take on more muted tones, the alvinellid worm (Paralvinella hessleri) dons a bright, golden yellow hue. This is in stark contrast to its gloomy surroundings – the worm lives far below the surface of the west Pacific Ocean, in mineral-rich hydrothermal vents where hydrothermal fluids mix with deep sea water and no other species dare venture.
Not only does the worm face extraordinary hot temperatures, but this part of the ocean is laced with high levels of arsenic and sulfide that would prove lethal to most animals.
“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,” Dr. Hao Wang of the Institute of Oceanology at the Chinese Academy of Sciences (CAS) said in a supporting statement. “It was hard to believe that any animal could survive, let alone thrive, in such an extreme and toxic environment.”
Read More: Spiky, Star-Shaped Creatures Show the Deep Sea Is a “Connected Superhighway”
Adapting to Extreme Environments
These extreme dwellings do offer some benefits. The intense heat and sheer toxicity of the habitat deters predators and discourages competitors, granting P. hessleri access to an abundant food supply.
But how does it alone survive such hazardous environments? Using advanced microscopy in combination with DNA, protein and chemical analyses, the team discovered a novel detoxification process.
The results suggest particles of arsenic can build up to the point where the chemical accounts for almost 1 percent of the worm’s total body weight. These arsenic particles react with sulphides found in the habitat, neutralizing both substances and converting the chemicals into small clumps of a material that proves to be less harmful to the worm – orpiment.
“This process represents a remarkable adaptation to extreme chemical environments,” the study’s authors write. “Our study provides new insights into understanding animals’ environment adaptation mechanisms and the diversity and plasticity of biomineralization.”
As well as enabling to P. hessleri withstand such a toxic environment, the presence of orpiment in the creature’s epidermal tissues is responsible for its unusually bright coloring.
Read More: These 12 Deep Sea Creatures Are More Comical Than Creepy
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