DEVELOPMENT OF THE SEA-STAR, ASTERINA BATHERI GOTO

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Abstract
Using natural spawning and artificial fertilization, the entire process of development from eggs to juveniles was observed in the sea-star, A. batheri Goto. The breeding season of this animal in Tsukumo Bay and Toyama Bay [Japan] was late summer. Spawned eggs were approximately 430 .mu.m in diameter and floated near the sea water surface. They developed through a wrinkled blastula stage by holoblastic, radial cleavage, into a pear-shaped brachiolaria bearing 3 blunt brachiolar arms. Metamorphosis took paace while the brachiolariae were swimming. Ten days after fertilization, metamorphosis was completed; the resulting juveniles were about 800 .mu.m in diameter and colored pale brown with a green tint. They bore 2 pairs of tube-feet and a terminal tentacle in each arm. Development of this species was of the direct type, and very similar in every respect to that of A. coronata japonica, to which it was closely related.