Timing of the water-to-land transition and metamorphosis in the land hermit crab Coenobita compressus H. Milne!Edwards:: evidence that settlement and metamorphosis are de-coupled
Timing of the water-to-land transition and metamorphosis in the land hermit crab Coenobita compressus H. Milne!Edwards:: evidence that settlement and metamorphosis are de-coupled
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DOI：
10.1016/s0022-0981(02)00039-4
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发表时间：
2002-06-10
影响因子：
2
通讯作者：
Brodie, RJ
中科院分区：
文献类型：
--
作者：
Brodie, RJ
寄居蟹（Coenobita compressus）在海洋浮游生物中从最后的幼虫阶段蜕变到过渡的巨蛋阶段后，向岸上移动，在那里它经历了第二次蜕变，成为陆地上的第一个幼星。在两个实验中，我使用实验室饲养的螃蟹，在这一阶段的不同时间后，我将巨蛛从水中移到陆地上，并研究了这种操作对第二次变态的时间和生存的影响。在非自愿定居实验中，巨蛛在3、6、9、12或15天大的时候被转移到陆地上。在3天到6天之间活动的巨翅虫没有一个能通过蜕变存活下来，但大多数9天大的巨翅虫存活了下来，大多数12天和15天大的巨翅虫也是如此。这表明巨蛋期早期的发育变化为陆地生命做好了准备。一旦在陆地上，在第9天被移到陆地上的巨翅虫在蜕变前又在那里多呆了9天，而12天和15天大的巨翅虫分别在陆地上待了5天和4天后就蜕变了。在自愿定居实验中，巨蛋在出生1、5、10或15天时可以获得土地，但不强迫它们进行过渡。那些在1天后获得土地的人在平均7天后首次自愿离开他们的盘子。那些在5天大的时候被喂食的老鼠在水里待了大约4天，而那些在10天和15天大的时候被喂食的老鼠在不到一天的时间里就离开了。在这两个实验中，相对于定居（即向陆地过渡）的变质时间表明，这些事件在一定程度上是分离的，并揭示了变质时钟的存在。我讨论了为什么定居和蜕变的分离可能在陆地寄居蟹和另一种异源蟹中得到青睐。(C) 2002 Elsevier Science B.V.版权所有
After metamorphosing from the last larval stage to the transitional megalopal stage in the marine plankton, the hermit crab Coenobita compressus moves ashore where it undergoes a second metamorphosis to the first juvenile instar on land. In two experiments using laboratory-reared crabs, I moved megalopae from water to land after different amounts of time at this stage and investigated the impact of this manipulation on the timing of and survival through the second metamorphosis. In the Involuntary Settlement experiment, megalopae were moved to land when they were 3, 6, 9, 12, or 15 days old. None of those moved between the ages of 3 and 6 days survived through metamorphosis, but the majority of 9-day-old megalopae survived, as did most 12- and 15-day-old megalopae. This suggests that developmental changes early in the megalopal stage prepare C compressus for terrestrial life. Once on land, megalopae that had been moved to land at 9 days spent about nine additional days there before metamorphosing, while 12- and 15-day-old megalopae metamorphosed after spending about 5 and 4 days, respectively, on land. In the Voluntary Settlement experiment, megalopae were given access to land when they were 1, 5, 10, or 15 days old, but were not forced to make the transition. Those given access to land after I day voluntarily left their dishes for the first time after an average of 7 days in water. Those given access when they were 5 days old remained in water about 4 days longer, while those given access when they were 10 and 15 days old left after less than a day. In both experiments, the timing of metamorphosis relative to settlement (i.e., transition to land) showed that these events are dissociated to a degree and revealed the presence of a metamorphic clock. I discuss why the dissociation of settlement and metamorphosis may have been favored in the land hermit crab and in another anomuran crab. (C) 2002 Elsevier Science B.V. All rights reserved.