Life history of the Antarctic tardigrade, Acutuncus antarcticus, under a constant laboratory environment

Tardigrades are found in most terrestrial and freshwater Antarctic ecosystems and are one of the most diverse and important groups of invertebrates in Antarctica. We developed a new laboratory system for rearing the Antarctic tardigrade Acutuncus antarcticus (Richters 1904), one of the most widespread and common Antarctic tardigrade species. To provide a description of the life history of this tardigrade, survival and reproduction of 68 individuals were observed and recorded daily at a constant temperature of 15 °C. The life-history data obtained are consistent with previous studies of other tardigrades. The exceptionally high hatching success obtained is suggested to be an important life-history characteristic of this species contributing to it often being a common and dominant species in the Antarctic habitats in which it occurs. Furthermore, high hatching success combined with very low variation in development time, under the protocol used in the current study, indicates that A. antarcticus may be a good model species for studies in developmental biology. Integrating data from this and previous studies, the importance of temperature on reproduction and growth in A. antarcticus was inferred. With terrestrial and freshwater ecosystems in some parts of Antarctica experiencing sometimes drastic contemporary climatic and environmental changes, studies of the effect of temperature on generation time and reproductive success in Antarctic tardigrades are urgently required, as these animals are important elements of community structure and function in polar ecosystems.