Implications of sublethal predation, autotomy and regeneration: pigment bands on their spines can not be used to determine the ages of adult specimens of the corallivore Acanthaster planci

Abstract

Attempts to determine the ages of five adult specimens of Acanthaster planci from the pigment bands on the aboral spine ossicles were unsuccessful because there was little coincidence in the number and arrangement of the bands on different spines obtained from the same starfish. Hence, different spines often yielded markedly different putative ages. Spines along the midline of an arm usually possessed more bands than did those from the edge; the further from the central disc the location of an arm spine, the fewer bands it carried; and the numbers of bands on spines from the regenerating portions of arms were always significantly fewer than those on spines from intact portions of arms. Spines from intact portions of different arms from the same starfish yielded different putative ages, and the mean putative age of arm spines was greater than, similar to, or less than that of spines from the central disc. It was concluded that the putative age derived from the banding patterns on the aboral spines of a starfish bears no relationship to the actual age of the starfish but reflects its recent history of spine autotomy, sublethal predation and regeneration.