Life is set within a narrow frame of physicochemical factors, yet, some species have adapted to conditions far beyond these constraints. Nature appears to have evolved two principal strategies for living organisms to cope with hostile conditions. One way is to remain active, retaining metabolism through adaptations that enable the organism to match the physiological requirements of environmental change. The other is to enter a state of dormancy with metabolic suppression. One form of metabolic suppression, known as cryptobiosis, is a widespread state across life kingdoms, in which metabolism comes to a reversible standstill. Among animals, nematodes, rotifers and tardigrades, comprise species that have the ability to enter cryptobiosis at all stages of their life cycle. Tardigrades are microscopic cosmopolitan metazoans found in permanent and temporal aquatic environments. They are renowned for their ability to tolerate extreme stress and are particularly resistant after having entered a cryptobiotic state known as a “tun”. As new molecular tools allow for a more detailed investigation into their enigmatic adaptations, tardigrades are gaining increasing attention. In this graphical review, we provide an outline of survival strategies found among tardigrades and we summarize current knowledge of the adaptive mechanisms that underlie their unique tolerance to extreme or changing environments

生命被设定在一个狭窄的物理化学因素框架内，然而，一些物种已经适应了远远超出这些限制的条件。大自然似乎已经为生物体进化出两种主要策略来应对恶劣条件。一种方法是保持活跃，通过适应来保持新陈代谢，使生物体能够适应环境变化的生理需求。另一种是进入休眠状态，代谢抑制。代谢抑制的一种形式，称为隐生，是一种广泛存在于生命王国中的状态，在这种状态下，新陈代谢处于可逆的停滞状态。在动物中，线虫、轮虫和缓步动物包括能够在其生命周期的所有阶段进入隐生环境的物种。缓步动物是在永久性和暂时性水生环境中发现的微观世界性后生动物。它们以耐受极端压力的能力而闻名，并且在进入称为“tun”的隐生状态后尤其具有抵抗力。随着新的分子工具允许对其神秘的适应进行更详细的研究，缓步动物越来越受到关注。在此图形审查中，我们概述了在缓步动物中发现的生存策略，并总结了它们对极端或变化环境的独特耐受性基础的适应性机制的当前知识 随着新的分子工具允许对其神秘的适应进行更详细的研究，缓步动物越来越受到关注。在此图形审查中，我们概述了缓步动物中发现的生存策略，并总结了当前对适应机制的了解，这些机制是它们对极端或不断变化的环境的独特耐受性的基础 随着新的分子工具允许对其神秘的适应进行更详细的研究，缓步动物越来越受到关注。在此图形审查中，我们概述了缓步动物中发现的生存策略，并总结了当前对适应机制的了解，这些机制是它们对极端或不断变化的环境的独特耐受性的基础