Tardigrades seem to have a weakness according to a new study published in Scientific Reports and carried out by researchers at the University of Copenhagen. Tardigrades are microorganisms known to be one of the most resistant living species.
This is also due to a characteristic that makes them enter a sort of “suspended animation” during which the body dries out. Just during this phase, it is possible to insert them in practically any environment present on Earth, from those with no oxygen to those with icy temperatures, or even those of space, with its vacuum and cosmic radiations, without these animals suffering any damage.
There are currently 1300 known species and most of them are between 0.3 and 0.5 mm long. They can be found in every environment, from humid to freshwater, from the equator to the poles. The new study focused on a species of tardigrade, the Ramazzottius variornatus, which seems to have a weakness. After having taken several samples of this species from a site in Denmark, the biologist Ricardo Neves of the University of Copenhagen has exposed this species to the high temperature realizing that, especially for those tardigrades which had not had the time to acclimatize to the change of temperature, there was a mortality rate of 50% after only 24 hours and at a temperature of only 37 °C.
Mortality was reduced if the tardigrades were given a short period of acclimatisation of a couple of hours at 30° and another couple of hours at 35°. This is for tardigrades not in “hibernation”: those in “drying” phase showed a higher resistance rate and the mortality rate of 50% was reached after 24 hours at a temperature of 63.1°. As the temperature increased further, the microorganisms began to die faster and faster.
According to Neves himself, this research shows that tardigrades in active phase are vulnerable to high temperatures while those in “dried” phase are more leathery as they can withstand much higher temperatures, almost twice as high, but not at those temperature levels theorized by other previous studies according to which tardigrades can tolerate temperatures up to 151° centigrade. In any case, much depends also on the period of acclimatization that these animals seem to need when talking about temperatures.