Post-autotomy appendage movement has evolved independently in several vertebrate and invertebrate taxa. Moving appendage may divert a predator’s attention away from the body, allowing the prey to escape. Decapod crustaceans, particularly anomuran and brachyuran crabs, have been well studied in terms of autotomy; however, no studies have focused on post-autotomy limb behaviour. We first found post-autotomy limb movement in decapod crustaceans using the porcellanid crab Petrolisthes japonicus. Porcellanid crabs possess large chelipeds. The porcellanid crab autotomizes the cheliped readily when a predator crab grasps it by the cheliped, enabling it to escape. Our laboratory observations revealed that autotomized chelipeds of P. japonicus moved voluntarily: they repeated closing and stretching movements of the chela and remaining parts on the propodus-carpus joint. The number of strokes (a single sequential closing and stretching movement) and the total stroke duration of the chelipeds were about 28 times and 17 sec on average, respectively. Post-autotomy cheliped movement may further improve the anti-predator defence efficacy of large chelipeds with a hair-trigger autotomy response in porcellanid crabs.

在几个脊椎动物和无脊椎动物类群中，自体切除后附肢运动已经独立进化。移动的附肢可能会将捕食者的注意力从身体上转移开，从而使猎物逃脱。十足目甲壳类动物，特别是 anmuran 和 brachyuran 蟹，在自体解剖方面已经得到了很好的研究；然而，没有研究集中在自体切除后的肢体行为上。我们首先使用 porcellanid 蟹Petrolisthes japonicus在十足类甲壳类动物中发现了自体切除后肢体运动。猪蟹拥有大螯足。当捕食性螃蟹抓住螯足时，猪蟹很容易将螯肢自动切除，使其能够逃脱。我们的实验室观察表明，日本海参的自动切割螯足自愿移动：他们重复闭合和伸展螯合和前足-腕关节剩余部分的运动。中风次数（单次连续闭合和伸展运动）和螯足的总中风持续时间平均分别约为 28 次和 17 秒。自切后螯肢运动可能会进一步提高大螯肢在猪蟹中具有毛发触发自截反应的抗捕食者防御功效。