Caltech Scientists Discover Worms with Three Sexes

Caltech scientists have discovered a new species of worms thriving in the extreme environment of Mono Lake. It has been dubbed Auanema sp. and can survive 500 times the lethal dose of arsenic. It carries its young inside its body like a Kangaroo. 
Mono Lake, located in the Eastern Sierras of California, is three times as salty as the ocean and has an alkaline pH of 10. Before this study, only two other species (other than bacteria and algae) were known to live in the lake—brine shrimp and diving flies. In this new work, the team discovered eight more species, all belonging to a class of microscopic worms called nematodes, thriving in and around Mono Lake.
The work was done primarily in the laboratory of Paul Sternberg, Bren Professor of Biology. A paper describing the research appears online on September 26 in the journal Current Biology.
The Sternberg laboratory has had a long interest in nematodes, particularly Caenorhabditis elegans, which uses only 300 neurons to exhibit complex behaviors, such as sleeping, learning, smelling, and moving. That simplicity makes it a useful model organism with which to study fundamental neuroscience questions. Importantly, C. elegans can easily thrive in the laboratory under normal room temperatures and pressures.
As nematodes are considered the most abundant type of animal on the planet, former Sternberg lab graduate students Pei-Yin Shih (PhD '19) and James Siho Lee (PhD '19) thought they might find them in the harsh environment of Mono Lake. The eight species they found are diverse, ranging from benign microbe-grazers to parasites and predators. Importantly, all are resilient to the arsenic-laden conditions in the lake and are thus considered extremophiles—organisms that thrive in conditions unsuitable for most life forms.
The new worm exists in three different sexes: hermaphrodites, females, and males. The hermaphrodites can produce offspring by themselves, but the females and males need to mate in order to produce their young. The females and males are often produced early in the reproductive cycle of the mother, followed by the hermaphrodites.