PASADENA, Calif. — Mono Lake, found in California’s Eastern Sierras, is an extremely hard place to call home. The lake is three times as salty as the ocean and is largely uninhabitable. In fact, only two species, brine shrimp and diving flies, were known to live in the lake — that is, up until now. Scientists at the California Institute of Technology have discovered a completely new species of worm living in Mono Lake, and it has some fascinating and “otherworldly” characteristics.
This new worm species, temporarily being called Auanema sp., has three different sexes, carries its young inside its body in a manner similar to a kangaroo, and can even survive 500 times the lethal dose of arsenic in humans.
Besides Auanema sp., scientists also discovered eight additional species living in and around Mono Lake. All of these newly-found animals belong to a class of microscopic worms called nematodes.
The biology lab at CalTech has long been interested in the study of nematodes, particularly Caenorhabditis elegans, because they use a small amount of neurons (300) to accomplish complex biological functions like sleeping, moving, learning, and smelling. According to researchers, it’s this simplicity that makes these nematodes a great organism to study in reference to fundamental neuroscience questions. Perhaps just as importantly, C. elegans are easily maintained and studied in a laboratory setting.
Nematodes are believed to be the most abundant animal on Earth, so researchers hypothesized they may be present even in the harsh environment of Mono Lake. All eight nematode species discovered at the lake are different in their own way; some are parasites while others are predators by nature. However, all of the nematodes share a resistance to the high arsenic levels found in the lake. This feature means all eight are classified as extremophiles, or organisms that thrive under conditions that kill most other living beings.
Upon examining the Auanema sp. nematode specifically, researchers noted a few significant observations about the worm. First, after comparing the new Auanema sp. to sister species within the same genus, they discovered that many similar nematode species also displayed a high tolerance for arsenic, despite the fact that these species don’t live anywhere near Mono Lake. Additionally, the research team noted that the Auanema sp. is capable of thriving under normal living conditions. This is significant because only a few extremophiles in all the world are capable of being studied in a lab setting.
These findings indicate that nematodes in general are genetically predisposed to adapt and thrive in virtually any environment, whether it be extreme or benign.
“Extremophiles can teach us so much about innovative strategies for dealing with stress,” says former CalTech grad student and co-lead researcher Pei-Yin Shih in a media release. “Our study shows we still have much to learn about how these 1000-celled animals have mastered survival in extreme environments.”
Moving forward, the researchers plan to look for particular biochemical and genetic factors that allow nematodes to thrive in such harsh conditions. They are are going to sequence the genome of Auanema sp. and search for genes that specifically facilitate arsenic resistance. This research could prove fruitful in a number of unexpected ways. For example, arsenic-contaminated drinking water is a major global concern, and understanding how nematodes neutralize the harmful effects of arsenic may one day help humans better understand how the toxin moves through and impacts our own bodies.
“It’s tremendously important that we appreciate and develop a curiosity for biodiversity,” Pei-Yin Shih adds. “The next innovation for biotechnology could be out there in the wild. A new biodegradable sunscreen, for example, was discovered from extremophilic bacteria and algae. We have to protect and responsibly utilize wildlife.”
The study is published in the journal Current Biology.