Control of egg hatching in the terrestrial crab

河口陆栖蟹Sesarma haematocheir的胚胎在被释放到水中之前同时孵化。当胚胎附着在雌性身上时，卵孵化同步发生，并且已经研究了雌性在这种同步中的作用。从产卵雌性分离胚胎簇（每个200-2000个浆果），并将其孵化与附着在雌性上的胚胎进行比较。在一个集群中的离体胚中，要么全部孵化，要么没有孵化。此外，一个显着的特点是，在这些分离的鸡蛋孵化成功取决于孵化的鸡蛋仍然附着在女性的时间。在幼虫释放的预计时间的48-49.5小时内，从雌性分离的胚胎簇全部成功孵化，并出现游泳的蚤状幼体。但是，从雌性身上分离的胚胎在较长的时间内根本没有孵化出来，尽管它们显然是活的。这些结果表明， ...更多信息 与胚胎发育不同的孵化过程。此外，为了研究雌性和胚胎中的哪一个控制孵化的实际时间，将一簇胚胎分离并在两个产卵雌性之间交换。移植卵的孵化根据雌性中的一只或两只释放幼虫的过夜数分为三种模式。在模式I中，移植的集群独立地从附着于宿主雌性的卵孵化。在模式II中，当一个植入集群不受宿主雌性控制时，另一个移植集群的孵化被明显诱导。在模式III中，不仅孵化诱导，而且孵化时间由雌性控制。移植卵转移到通气条件下的孵化概况表明，孵化需要三个晚上，每个胚胎也有一个内源性成分孵化。由于雌性附着卵的孵化发生在很短的时间内，雌性必须有一些行动，以提高孵化同步时，实际孵化发生。一个合理的假设来解释的诱导和同步孵化在每个离合器的机制进行了讨论。少

Embryos of the estuarine terrestrial crab Sesarma haematocheir hatch simultaneously just before they are released into water. Egg hatching occurs synchronously when the embryos are attached to a female, and the role of the female in this synchrony has been investigated. Clusters of embryos(each 200-2000 berries)were detached from the ovigerous females, and their hatching was compared with that of embryos attached to the females. Of the detached embryos in a cluster, either all hatched, or none hatched. Moreover, a remarkable feature was that the success of hatching in these detached eggs depended upon the time of hatching of the eggs still attached to the female. Clusters of embryos that were detached from the female within 48-49.5 h of the projected time of larval release, all hatched successfully, and swimming zoeae appeared. But embryos that were detached from the female for longer time periods did not hatch at all, though they were obviously alive. These results suggest that the pr … More esence of a hatching process different from embryonic development. The female would trigger this process.Furthermore, to investigate which of female and embryo controls the actual timing of hatching, a cluster of embryos was detached and exchanged between two ovigerous females. Hatching of the transplanted eggs were divided into three patterns according to the number of nights until either or both of the females released larvae. In the Pattern I, transplanted clusters independently hatched from the eggs attached to the host female. In the Pattern II, while one of the implanted cluster was not controlled by the host female, hatching of another transplanted clusters was obviously induced. In the Pattern III, not only induction of hatching but also the time of hatching was controlled by the female. Hatching profiles of the transplanted eggs transferred into aerated conditions indicate that hatching requires three nights, and that each embryo also has an endogenous component for hatching. Since hatching of female-attached eggs occurs in a very short time, the female must have some action to enhance hatching synchrony when the actual hatching occurs. A plausible hypothesis to explain the mechanism as the induction and synchronization of hatching in each clutch is discussed. Less