Reproduction of the Slate Pencil Sea Urchin, Heterocentrotus mammillatus (L), in the Northern Red Sea

Abstract

The annual reproductive cycle of Heterocentrotus mammillatus was studied in the northern Red Sea. Gametogenesis starts in January, and the abundance of ripe gametes gradually increases until, by May, they occupy most of the gonadal volume. Spawning occurs in June and July; the pattern suggested a lunar or semilunar cycle. Assays of KC1 injections suggest that these may be a better indicator of reproductive ripeness than conventional oocytes-ova analysis. A highly significant linear relationship between gonad weight and total body weight was observed at the period of maximal gonad size prior to spawning.