…at least when it comes to dealing with warming temperatures. In contrast to their reputation for being able to withstand almost any extreme environment (radiation, cold, drought, vaccuum of space), researchers at the University of Copenhagen have found that tardigrades may have an Achilles heal. They appear intolerant of sustained increases in temperature.
Study author Dr. Ricardo Neves was quoted in Science Daily, “The specimens used in this study were obtained from roof gutters of a house located in Nivå, Denmark. We evaluated the effect of exposures to high temperature in active and desiccated tardigrades, and we also investigated the effect of a brief acclimation period on active animals.” As aquatic animals, tardigrades require water to be in an active state. In the absence of water, they dessicate and shut off their metabolism.
For active animals, i.e. not acclimated to heat, the temperature that was lethal to 50% was 37.1°C, which is surprisingly near the current maximum temperatures measured in Denmark (36.4°C). Animals that were dessicated, on the other hand, could withstand a much higher temperature of 82.7°C for one hour before succumbing to heat.
RC Neves, LKB Hvidepil, TL Sørensen-Hygum, RM Stuart, N Møbjerg. Thermotolerance experiments on active and desiccated states of Ramazzottius varieornatus emphasize that tardigrades are sensitive to high temperatures. Scientific Reports, 2020; 10 (1) DOI: 10.1038/s41598-019-56965-z