Tardigrades are microscopic sized Ecdysozoans. In Iran, in the last year and for the first time, these animals were identified and reported in Mashhad, and it immediately became an important question that what is the extent of tolerance and biological and reproductive details of these animals in Iran. Therefore, in this study, it has been tried to study the mechanism of biological and physiological adaptations, especially to temperature and humidity stresses. Also, the development stages of the living details of these animals should be studied and compared with other studies in other climates. For this purpose, sampling was conducted from valleys and basins in Mashhad city during four seasons of 2014 to 2016. After identification of the species, films were recorded for these animals at least 6 hours per day, and the results of this study have been gathered on the favorable environmental conditions, reproductive details and development of eggs, nutrition, and other factors.