How long can tardigrades survive in anhydrobiotic state? Searching on tardigrade anhydrobiosis patterns

Anhydrobiosis is a desiccation tolerance that denotes the ability to survive almost complete dehydration without sustaining damage. However, knowledge on the survival capacity of anhydrobiosis in various species of tardigrades is still very limited. Our research has compared anhydrobiotic capacities of four tardigrade species: Echiniscus testudo, Paramacrobiotus experimentalis, Pseudohexapodibius degenerans and Macrobiotus pseudohufelandi, which differ in feeding behaviour, habitats occupied, and which belong to different genera. Moreover, in the case of Ech. testudo two populations-from urban and natural habitats-were analysed. Clear differences in the anhydrobiotic capacity were observed among different tardigrade species. These differences appear to be determined by the habitat, but not by the nutritional behaviour of the species sharing the habitat type. Moreover, the results indicated that the longer tun state duration, the more time was necessary for the animals to return to activity.