Origin of Concentric Banding in the Spines of the Tropical Echinoid Heterocentrotus

Abstract

The concentric bands or rings which are evident in transverse sections of echinoid spines have attracted the interest of biologists for more than a hundred years. First, the basic cause of ring formation remains obscure although at least two controversial hypotheses have been proposed, and elucidation of the ring-forming mechanism is important to a better understanding of the general processes involved in growth. Second, there is a practical aspect to the "growthring problem" because, if the number of rings in a spine is closely and directly related to the age of the animal, killing the urchin for age determination is obviated, thus facilitating ecological, population, and other practical studies in marine research.