Morphology and Haemolymph Composition Changes in Red Sternum Mud Crab (Scylla serrata)

Abstract

Characteristic differences between the abnormal, red sternum mud crab compared to those of normal one were clearly seen. A red sternum mud crab had soft carapace, red chelae and joint, pale hepatopancreas and gill, loose muscle, while its haemolymph contained milky unclotted substance. SDS-PAGE analysis of protein in haemolymph showed an intense band of oxyhemocyanin (~75 kDa) in normal crab, but none in red sternum crab as also confirmed by the absence of 340 nm absorbance of oxyhemocyanin. As for trace elements, the content of copper and zinc in haemolymph was found to be three and four times higher than those in normal crab but calcium, magnesium and iron were higher in red sternum crab. These results indicated that red sternum mud crab had lost oxyhemocyanin and some important elements in haemolymph which were necessary to maintain the normal morphological features of this mud crab.