EFFECTOR MECHANISMS 



395 



resembling phosphoarginine; this sometimes occurs with another substance 

 resembling creatine phosphate. The presence of both phosphocreatine and 

 phosphoarginine in echinoids and enteropneusts, and of phosphocreatine 

 in ophiuroids and cephalochordates, is interpreted as confirmatory 



TABLE 9.3 

 Distribution of Phosphagens in Marine Animals 



1 Contain phosphagens resembling arginine phosphate and creatine phosphate. (Baldwin and Yudkin 

 (13); Baldwin (12).) 



biochemical evidence of the phylogenetic relationship between echinoderms, 

 protochordates and vertebrates (12, 13, 23, 31, 32a, 37, 52a, 86, 124, 130, 

 131). 



ELECTRIC ORGANS 



Organs which generate electrical shocks have evolved independently in 

 several groups of fish. These include the freshwater electric eel Elec- 

 trophorus, and marine torpedoes, rays and stargazers {Astroscopus). In 

 nearly all fish the electric organ is derived from muscle. The electric organ 

 of Torpedo represents modified branchial muscle; that of Raja, lateral 

 caudal muscle; and the organ of Astroscopus, one of the eye muscles. 

 The two electric organs of the torpedo lie at the bases of the pectoral 



