Scientists Find Three-Sex, Arsenic-Resistant Nematode in Nearly Uninhabitable Lake

The new nematode
Image: Paul Sternberg

Scientists have discovered an extreme nematode that has three sexes, raises its larvae in a pouch like a kangaroo, and can withstand 500 times the arsenic concentration that humans can, according to a new study.

We all know that on Earth, life (uh) finds a way, but some animals have figured out how to survive ridiculously brutal conditions. This nematode’s survival in California’s super salty and arsenic-filled Mono Lake might help scientists better understand the effects of arsenic on human biology.


“Perhaps we can figure out new pathways that animals such as ourselves may be able use to our advantage,” study co-first author James Lee from Rockefeller University told Gizmodo.

Mono Lake is a 8-by-13-mile lake in Eastern California that water can flow into but not out of. This causes the lake to accumulate high amounts of salts and other elements. Scientists previously only identified two animals living therebrine shrimp and a species of fly—though it serves as an important migratory stopover point for birds that feed on the shrimp. But when a team of researchers sampled the water, they found eight species of nematodes, a kind of worm. One of these was a whole new species.

Mono Lake
Photo: Paul Sternberg

This new species of nematode, temporarily called Auanema sp., was weird, even by extreme creature standards. Researchers were able to cultivate the worm in the lab, something quite difficult to do for other extremophiles. It has has three sexes, male, female, and hermaphrodite, and it gives birth to live larvae after hatching them in a pouch, according to the paper published in Current Biology. This might serve as a form of parental care so that the young can survive Mono Lake’s harsh conditions, Lee said.


Most surprisingly, lab tests found that the worm could withstand around 500 times the human lethal limit of arsenic for hour. The species is one of several in the genus that show a level of arsenic resistance. Perhaps some nematodes are pre-disposed to extremophile living, the scientists write.

Arsenic is a potential groundwater pollutant, and an estimated 200 million people worldwide live in areas with higher-than-safe arsenic levels in their drinking water. Lee said that these nematodes could provide a way to further study the interaction between arsenic and the body.


Life is found even in some of the harshest conditions Earth has to offer. Just take it from this weird worm.

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About the author

Ryan F. Mandelbaum

Senior writer covering physics / Founder of Birdmodo