Amino acids and some other nitrogenous compounds inCalanus finmarchicus

Amino acids, both free and combined as protein, and some other nitrogenous constituents of Calanus finmarchicus have been examined. Seventy-six per cent of the total nitrogen in C. finmarchicus was present in protein amino acids, 14% in the free amino acid fraction, 6% in trimethylamine oxide, and 1·5% in betaine. These findings are discussed in relation to previous work on nitrogenous constituents of Calanus . The free amino acid fraction of Calanus is compared with that of higher Crustacea and it is suggested that this fraction may be important in the adaptation of the animal to dilute sea water. Amino acid nitrogen made up 40% of the total nitrogen of particulate material from Clyde sea water. This finding is compared with other recent analyses of the phytoplanktonic nitrogen and total particulate nitrogen of inshore waters.