Some Observations on Bipinnariae and Juveniles of the Starfish GenusLuidia

Abstract

The bipinnaria larva of the five-armed starfish Luidia sarsi Diiben and Koren is unusual among bipinnariae in being exceptionally large, and more especially in that at metamorphosis the larval body detaches from the juvenile starfish it has carried and nurtured, to continue a separate existence for a considerable time. In the closely related seven-armed Luidia ciliaris (Philippi) the larva is much smaller and the larval body is completely absorbed, as is usual with starfish larvae. In neither species does a brachiolaria stage precede metamorphosis. The bipinnaria of Luidia sarsi has been especially well described and illustrated, with a discussion of earlier observations, by Tattersall & Sheppard (1934). Recorded here are my observations on the metamorphosis of six bipinnariae of Luidia sarsi and one of Luidia ciliaris, and on the subsequent growth and habits of the young starfishes developed from them. Three of the former species metamorphosed in accordance with previous accounts, but three others differed in that the larval body was partially absorbed to a greater or lesser degree.