The annelid phosphagen: with a note on phosphagen in Echinodermata and Protochordata

Abstract

A new, arginine phosphate-like phosphagen is present in annelid and gephyrean worms. A second phosphagen, possibly identical with creatine phosphate, has also been found in certain annelids but not so far in gephyreans. This second phosphagen sometimes co-exists with the first, but is found alone in some species. The distribution of these two phosphagens does not appear to be correlated with physiological activity or with environmental factors. Arginine could not be isolated from either of two annelids or one gephyrean species; a new base is, however, present in the guanidine fraction and has been isolated as the picrate. It has not yet been identified. The significance of these observations is discussed in relation to the taxonomic status of the Annelida and Gephyrea. It is indicated that there exists a close relationship between these groups. The new ‘annelid phosphagen' is, apparently, confined to the Annelida and Gephyrea, which are thus chemically distinguishable from the Arthropoda and Mollusca. Some new data are presented concerning the distribution of arginine and creatine phosphates in Echinodermata and Hemichordata, and the evidence concerning these two groups is reviewed with special reference to the echinoderm-hemichordate theory of vertebrate ancestry. It is concluded that existing data support this theory, and that the new information concerning the phosphagens of the annelids serves to emphasize the wide divergence that exists between the segmented invertebrates and the true Chordata.