Even the almost invulnerable tardigrades will fall victim to global warming

Even the almost invulnerable tardigrades will fall victim to global warming

The most difficult animal to kill on Earth is the so-called water bear or tardigrade : a microscopic invertebrate 0.1 or 0.2 mm long with eight stubby legs, claws and a head like a small probe.

However, even its proverbial endurance will be insufficient to tolerate global warming , according to a new study from the University of Copenhagen published in Scientific Reports .

Vulnerable to heat

As the study reveals, tardigrades are highly vulnerable to long-term heat in the active state . Specifically, the species Ramazzottius varieornatus , a tardigrade that is frequently found in transient freshwater habitats, was studied.

The researchers estimated that for unacclimatized active tardigrades, the mean lethal temperature is 37.1 ° C. For dried tardigrade samples, the authors noted that the estimated mortality temperature of 50% is 82.7 ° C after 1 hour exposures, although a significant decrease was recorded at 63.1 ° C after 24 hour exposures.

As explained by postdoc Ricardo Neves , one of the study’s authors:

From this study, we can conclude that active tardigrades are vulnerable to high temperatures, although it seems that these creatures could acclimate to increased temperatures in their natural habitat. Dried tardigrades are much more resistant and can withstand much higher temperatures than those supported by active tardigrades. However, the exposure time is clearly a limiting factor that limits your tolerance to high temperatures.

Tardigrades are creatures less than a millimeter long that can survive when subjected to temperatures of up to 150 ° C and frozen to near absolute zero. It is quite likely that they are even inhabiting the Moon , but it does not seem that they will be able to tolerate high temperatures for long .