220 



9 (6). Larva with four pairs of arms. 

 10(11). All terminal processes on basal rays with many short spines. . . . 



Amphipholis kochii, Stage II 



11(10). Only two terminal processes of basal rays with spines 



Ophiura sarsi, Stage II 



FAMILY CHARACTERS OF LARVAL BRITTLE STARS 



Ophiuridae 



It is not possible to identify only one type of development as typical for the 

 brittle stars of this family. Planktotrophic and lecithotrophic larvae as well as 

 brood care have been observed here. In the planktotrophic type, larval devel- 

 opment is marked by very slender, elongate posterolateral arms; the rays 

 supporting them may be fenestrated in some species. A fully developed larva 

 has four pairs of arms. At later stages a bright green stomach becomes very 

 distinct. The pigment in the arms and body of the larva varies in color in 

 different species. Unlike larval sea urchins, there are no vibratile plates, 

 pedicellariae and ciliated epaulettes. 



Ophiura sarsi Liitken and Ophiura sarsi vadicola Djakonov are found in 

 the Sea of Japan. The larvae have been described by Kryuchkova (1988). 



Amphiuridae 



Viviparity is characteristic of most of the studied species of this family. 

 During planktotrophic development of the larva the typical pluteus with four 

 pairs of arms develops. The transition to a larva with one pair of arms 

 occurred in the course of evolution of viviparity. The skeletal rods are simple 

 in all larvae. In larvae with four pairs of arms the body is compact and opaque 

 in the early stages; at later stages the body becomes almost transparent. In 

 larvae with a reduced number of arms the body continues to remain opaque 

 at all stages of development. At later stages, in species with a fully developed 

 larva an orange or red pigment appears along the rods supporting the arms 

 and at the end of the arms. 



One species, Amphipholis kochii Liitken, is found in Peter the Great Bay. 

 The larva of this species has been described by Yamashita (1985) and 

 Kryuchkova (1988). 



