FREE AMINO ACIDS IN INVERTEBRATES 163 













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PENAEUS CLIBINARIUS PAGURUS LITHOPHAGA LOLIGUNCULA 
Fig. 1. Amino acid contents of marine invertebrates. 
are metabolized and interconverted in similar ways as in the mammal!*. Some species 
may possess unique characteristics which deserve further study but no more. The 
abundance of glycine was mentioned ; in other species, particularly among the molluscs, 
taurine is present in very high amounts as will be shown later. In some other species, 
other amino acids are abundant; in the hemolymph of the Orthoptera Anacridium 
aegyptium three amino acids accounted for 50%, of the total free amino acid nitrogen, 
namely glycine, proline and glutamic acid?®. In a survey of 17 different marine inverte- 
brates Srupson et al. found that most of the free a-amino acid nitrogen was distributed 
in a few amino acids, namely the three amino acids which form a link with the citric 
acid cycle: alanine, aspartic acid and glutamic acid (glutamine) and also glycine. 
Taurine was abundantly present in all marine forms (Fig. 1). The aromatic amino 
References p. 174/175 
