2010 Volume 4 Pages 8-14
Blood osmolality of the mud crab (Scylla serrata) and blue swimming crab (Portunus pelagicus) was examined 0, 1, 3, 6, 9, 12, 24, 48, 72 and 96 hrs after transferred from seawater of salinity of 30 ppt to salinities of 5, 10, 15, 20, 25, 30 (control), 35 and 40 ppt at 25°C. Blood osmolality of both crab species reached to constant levels within 72 hrs. S. serrata survived for 96 hrs in all salinities tested whereas P. pelagicus survived for 96 hrs in salinities of 15, 20, 25, 30, 35 and 40 ppt but died 12 hrs after transferred into salinities of 5 and 10 ppt. Thus, the salinity ranges over which osmoregulation was performed efficiently were 5 - 40 ppt for S. serrata and 15 - 40 ppt for P. pelagicus. The results showed that S. serrata is a strong hyperosmotic regulator whereas P. pelagicus is an ordinary osmoconformer. This study could probably provide a laboratory model for teaching of osmotic regulation system for high school biology.
