Moulting is essential for crustacean growth, but is one of the causes of mortality, because a crustacean cannot move during and just after its ecdysis. In the cases of ectosymbiotic crabs, escape from the host's hostile response may also be a problem during its own ecdysis. In this study, Sestrostoma sp. (Varunidae), an ectosymbiotic crab which clings to the ventral abdomen of upogebiid shrimps with legs that can walk, was studied to clarify how the crab moults and maintains association with the host. Five cases of crab ecdysis were observed, where the crab moulted with its legs clinging to the host abdomen, without detaching from the host body. Time required for moulting was 14–21 min. Shedding of the old exoskeleton (active phase) took only 40–59 s. Sestrostoma sp. detached from the host abdomen and waited in the burrow tube during shrimp ecdysis. The crab then reattached at the same location on the host when shrimp moulting was complete. Our results suggest that Sestrostoma sp. are able to maintain a symbiotic relationship with the same shrimp host after its own ecdysis as well after ecdysis of its host.

中文翻译：

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外共生蟹（Sestostoma sp.）在蟹及其虾类宿主蜕皮过程中的行为策略

换羽对于甲壳类动物的生长至关重要，但也是导致死亡的原因之一，因为甲壳类动物在蜕皮期间和蜕皮后不能移动。在外共生蟹的情况下，逃避宿主的敌对反应也可能是其自身蜕皮过程中的一个问题。在这项研究中，塞斯特斯托马sp。（Varunidae）是一种外共生蟹，它附着在具有可以行走的腿的upogebiid虾的腹腹部，被研究以阐明螃蟹如何蜕皮并与宿主保持联系。观察到5例螃蟹蜕皮，螃蟹蜕皮时腿紧贴寄主腹部，未脱离寄主身体。换羽所需时间为 14-21 分钟。旧外骨骼（活跃期）的脱落仅用了 40-59 秒。塞斯特斯托马sp。虾蜕皮时脱离宿主腹部，待在洞穴管中。当虾蜕皮完成后，螃蟹会重新附着在宿主的同一位置。我们的结果表明塞斯特斯托马sp。能够在自身蜕皮后以及宿主蜕皮后与同一虾宿主保持共生关系。