Changes during late-stage embryonic development from egg-juvenile to free-living hatchling in Chinese freshwater crab Sinopotamon yangtsekiense (Decapoda, Brachyura, Potamidae)  

作　　者：薛俊增 刘艳 Neil CUMBERLIDGE 吴惠仙 

机构地区：[1]Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources,Shanghai Ocean University [2]Department of Biology,Northern Michigan University,Marquette

出　　处：《Chinese Journal of Oceanology and Limnology》2013年第3期542-551,共10页中国海洋湖沼学报（英文版）

基　　金：Supported by the Leading Academic Discipline Project of Shanghai Municipal Education Commission(No.J50701)

摘　　要：This study expands on recent reports that direct development in the Chinese potamid freshwater crab Sinopotamon yangtsekiense involves the completion of all brachyuran larval stages (nauplius, zoea, and megalopa) inside the egg case during embryonic development. Detailed studies of embryonic development in this species revealed the presence of an additional larval stage (the egg-juvenile) between the megalopa and the free-living hatchling crab. We described and compared the appendages of the head, thorax, and abdomen of the egg-juvenile with those of the hatchling crab in S. yangtsekiense. Significant differences were found between most of the appendages of these two stages with a soft exoskeleton in the egg-juvenile, no joint articulation, a slimmer appearance, and a lack of setae when compared with the newly emerged free-living hatchling crab. These modifications of the appendages are related to the confinement within the egg case of the egg-megalopa and egg-juvenile during direct development, and the need for the free-living hatchling freshwater crab to move, feed, and respire. In marine crabs, the megalopa gives rise to the first crab stage whereas in freshwater crabs the egg-juvenile follows the megalopa and immediately precedes the free-living first crab stage.This study expands on recent reports that direct development in the Chinese potamid freshwater crab Sinopotamon yangtsekiense involves the completion of all brachyuran larval stages （nauplius, zoea, and megalopa） inside the egg case during embryonic development. Detailed studies of embryonic development in this species revealed the presence of an additional larval stage （the egg-juvenile） between the megalopa and the free-living hatchling crab. We described and compared the appendages of the head, thorax, and abdomen of the egg-juvenile with those of the hatchling crab in S. yangtsekiense. Significant differences were found between most of the appendages of these two stages with a soft exoskeleton in the egg-juvenile, no joint articulation, a slimmer appearance, and a lack of setae when compared with the newly emerged free-living hatchling crab. These modifications of the appendages are related to the confinement within the egg case of the egg-megalopa and egg-juvenile during direct development, and the need for the free-living hatchling freshwater crab to move, feed, and respire. In marine crabs, the megalopa gives rise to the first crab stage whereas in freshwater crabs the egg-juvenile follows the megalopa and immediately precedes the free-living first crab stage.

关 键 词：Sinopotamon yangtsekiense freshwater crab embryonic development egg-juvenile hatchlingcrab appendage 

分 类 号：S917.4[农业科学—水产科学]