Female blue crab
Aspects of osmoregulation in two species of intertidal crabs. The composition of fluids and sera of some marine animals and of the sea water in which they live. A study of the glycogen and sugar content and the osmotic pressure of crabs during the molt cycle. Osmoregulating capacity in populations occurring in different salinities. This differential could be one of the factors that cause adult female crabs to move to higher-salinity water, but limit males to brackish water.Īnderson, J. The difference between sexes is at least partly due to their differential abilities to regulate sodium in the blood. The total blood osmoconcentrations of females increased, though not proportionately, with increases in salinity of the external media: 0.95 osmoles/liter in 10‰ water, 1.01 osmoles/liter in 20‰ water, and 1.18 osmoles/liter in 30‰ water. The males maintained an average blood osmoconcentration of 1.08 osmoles/liter in 10‰ and 20‰ waters and had a mean of 1.14 osmoles/liter in 30‰ water. Freezing-point depression determinations showed that all crabs were hyperosmotic to the media in which they were kept. After acclimation, blood samples were taken for physiological analysis. These crabs were arbitrarily divided into three groups, which were subjected to 10‰, 20‰ and 30‰ salinities at 20☌. 42 male and 46 female adult blue crabs, Callinectes sapidus Rathbun, were taken in early March from lower Chesapeake Bay.