. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 80 I. BOSCH Table II Embryonic and lecithotrophic larval development oftheundescribed inii'ii'id Porania .«/>. reared at 'C Developmental stage First appearance (days) Size* (mm) Zygote 0 Hatched hlastula 1? — Earl\ gastrula 21 Late gastrula 26 Pear-shaped larva 38 Early hrachiolaria 47 Late brachiolaria 68 Juvenile 75 * Refer to the diameter of zygotes and juveniles and the maximum length of all other stages. anterior lobe and was entirely lacking feeding structures (Fig. 3B)
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 80 I. BOSCH Table II Embryonic and lecithotrophic larval development oftheundescribed inii'ii'id Porania .«/>. reared at 'C Developmental stage First appearance (days) Size* (mm) Zygote 0 Hatched hlastula 1? — Earl\ gastrula 21 Late gastrula 26 Pear-shaped larva 38 Early hrachiolaria 47 Late brachiolaria 68 Juvenile 75 * Refer to the diameter of zygotes and juveniles and the maximum length of all other stages. anterior lobe and was entirely lacking feeding structures (Fig. 3B). These larvae were negatively buoyant and usu- ally swam near or on the bottom of stirred and unstirred culture vessels with the anterior lobe foremost and the anterioposterior axis in a horizontal attitude. Three bulbous arms first formed 47 days after fertiliza- tion: a single median anterodorsal arm, and a pair ofven- trolateral arms that occupy a region near the base of the narrow anterior lobe (Fig. 3C). Soon after, each arm was able to adhere temporarily to glass surfaces, and an adhe- sive disc had differentiated central to them. Therefore, the larva can be considered a modified brachiolaria. Fully developed brachiolariae (Fig. 3D) measured mm in length. Attachment to a substratum was initially accomplished by the brachiolarian arms and the adhe- sive disc. Metamorphosis included the complete degen- eration of the anterior lobe, and lasted from one to two weeks. During this period, some larvae detached from the bottom and continued to swim for hours to days. Fi- nal attachment was facilitated by the tube feet of the ju- venile rudiment. The newly metamorphosed sea star, about ± mm across (n = 10), had two pairs of tube feet on each of its 5 arms. The arms were short and difficult to distinguish due to the presence of yolk on the aboral surface of the disc. Discussion In echinoderms, and particularly asteroids, there are considerable differences (,
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