ABSTRACT
Echinothrix diadema (Linn.) like calamaris is found on the littoral region all over the Indo-Pacific. The purpose of this study is to determine what intraspecific differences in morphology exist between 2 populations of E. diadema living in Okinawa (26°N, 127°E) and Guam (13°N, 145°E) which are separated by a distance of 2700 km.
