We study and describe the life cycle of Plectus murrayi, a free-living, bacterivorous soil nematode endemic to terrestrial Antarctica. The study was performed at 15°C, a temperature identified as optimal for growth rate studies in the laboratory. Under these conditions, we observed that the first molt occurs in the egg, and second-stage juveniles hatch 12 to 14 d after egg laying. Individuals undergo three subsequent molts to become adults 23 to 26 d after hatching with a final average length of 950 μm. Egg-laying begins 41 to 43 d after hatching, resulting in an egg-to-egg life cycle ranging from 53 to 57 d under our experimental conditions. Considering that the average soil temperature during austral summers in the McMurdo Dry Valleys is only a few degrees above freezing, it is highly likely that many, if not most of these animals, require more than 1 yr to complete their entire life cycle. Our study supports other research that establishes P. murrayi as an important model organism for studying adaptation to extreme environmental stress.
Keywords: Anhydrobiosis; McMurdo Dry Valleys; physiology; soil fauna.