The early development of the sea urchin Diadema setosum (Leske, 1778)‎ in the region of north Jeddah, Red Sea

الملخص EN

Changes in the gonads of the sea urchin, Diadema setosum in northern Jeddah on the Red Sea, were followed over a year.

Maturation of gonads begins in April and spawning occurs mainly in early summer (from June to July).

Spawning of some mature specimens was induced by KCl-injection.

The optimal temperature for development was determined by incubation of batches of fertilized eggs at various temperatures (from 20 to 30°C).

Early development proceeded rather rapidly at 25°C over a period of 3-5 days.

The different stages of development from the onset of fertilization up to pluteus stage were described.

Typical radial cleavage is recorded.

Gastrulation is mainly by a combined process of embolic invagination and epiboly.