Development and metamorphosis of two psolid sea cucumbers,Psolus chitonoides andPsolidium bullatum, with a review of reproductive patterns in the family Psolidae (Holothuroidea: Echinodermata)

摘要: Reproduction and development of two psolid sea cucumbers in waters the San Juan Archipelago, Washington, were studied from April 1981 through August 1984. Spawning inPsolus chitonoides Clark andPsolidium bullatum Ohshima laboratory field occurred February may, with heaviest spawning May. The egg ofPsolus was bright red color 627µm diameter;Psolidium released eggs that golden yellow 330µm diameter. Maximum measured fecundities (spawned eggs) forPsolus 34 700 3 074, respectively. Developmental schedules similar both species. Early cleavages equal, radial, holoblastic; slightly subequal cleavage common chitonoides. gastrula elongated to form a uniformly ciliated larva vestibule first appeared as ventral crescent-shaped depression, after which decreased length formed three posterior ridges encircled early doliolaria. Just prior settlement, there loss cilia between on end doliolaria, leaving ciliary rings are characteristic dendrochirote doliolaria larva. Vertical swimming ensued, five primary tentacles protruded vestibule, occasional attachment substratum using tentacles. Upon podia emerged all external ciliation lost except among tentacular papillae tube feet. Timing appearance suggest function vertical selection behaviors. Metamorphosis involved following simultaneous events: (1) resorption preoral lobe, (2) formation large, dorsal, calcareous ossicles, (3) flattening trivium, (4) proliferation feet Ambulacral Radii B E sole. family Psolidae is reviewed. large proportion brooders this appears be related small size, possession protective armor sole, geographic distribution (mainly Antarctica). Lecithotrophic larvae produced by northern psolids.