Abstract

This paper approaches the discussion that took place during the second half of the Twentieth Century about the biological significance of the cryptobiotic state. Cryptobiosis has been defined as an evolutionary strategy in which organisms overcome adverse environmental conditions by entering a latency mode considered the third state between life and death. It is a poorly known phenomenon where metabolism, growth, reproduction and senescence are greatly reduced or cease temporarily. Since metabolism is conceived as a defining feature of life, it is argued that Cryptobiosis is a kind of temporal death, because metabolic activity sometimes seems to have stopped completely during the cryptobiotic state. In the following pages we deal with the cryptobiotic phase -as understood in the second half of the last Century-, considering two basic references: a case study, the case of group Tardigrada -small animals between a tenth of a millimeter and one millimeter that can survive in extreme conditions entering different states of latency-; and, secondly, the model around Cryptobiosis as recursive hierarchical metabolism proposed by Yair Neuman.