Blood Amino Acid Levels in the Freshwater Crab, <i>Barytelphusa guerini </i> H. Milne Edwards, as a Function of Salinity Adaptation

65-68Total free amino acids varied both qualitatively and quantitatively on adaptation to different salinities. Amino acid content increased in 25 and 100% sea water (SW) and the per cent increase was more in females in both media. While the increase in 100% SW was significant in both the sexes, the increase in 25% SW was significant only in females. Females showed a slight but insignificant increase in the intermediate salinities while a slight but Significant decrease was found in the males in the same salinities. Qualitative variations depended upon the sex and salinity of the medium. More new amino acids appeared in 25 and 100% SW while the new ones appearing at intermediate salinities were few. It is suggested that the concentration of amino acids in the blood and its contribution to the blood osmotic pressure depend more on the osmotic gradient than merely the salinity of the external medium. Importance of the choice of sex in studies on osmoregulation is also proposed .in view of the present findings