摘要：

Male adult paddy field crabs ( Oziotelphusa senex senex ) were adapted to salinity of 34%. After 3 months the gill lamella of the crab was sectioned and examined under an electron microscope and compared with that of freshwater crabs. The apical region nearest to cuticular boundary showed numerous foldings projecting into the cytoplasm of the epithelium. This brush border appearance disappeared in salinity-adapted crabs. Mitochondria also reduced in number in the sections of salinity adapted crabs. In seawater medium the crabs showed a hypo-osmotic regulation. This regulation is said to be involved in active sodium excretion through gills, in contrast to the active Na+ uptake found in freshwater crabs. The ultrastructural changes have been correlated with significant reduction in cholesterol and phospholipid molar ratios of the gill as well as Na + + K + ATPase and divalent ion ATPase activities of particulate system of the crab. The univalent ion ATPase activity served as a marker to show the reduced uptake of Na + on adaptation to higher salinity. The reduced Ca 2+ ATPase activity in the gills of seawater adapted crabs has been correlated with the reduced phospholipid content of the gill tissue.

展开