Colour Change in the Echinoid, Diadema antillarum, Philippi

Abstract

PHYSIOLOGICAL colour change has been but rarely reported in echinoderms¹. Mortensen², in a footnote, makes cautious reference to the possibility of such changes occurring in Diadema antillarum; but it is clear that he was not aware of the striking manifestation of the phenomenon reported here, which occurs in young forms of this species. Indications of the existence of a rhythmic change in colour persisting under constant external conditions do not appear to have been reported previously in this form, nor indeed, so far as I am aware, in any other echinoderm.