Meeting Abstract

53.1  Tuesday, Jan. 5  Larval Development and Metamorphosis of the Deep-Sea Cidaroid Urchin Cidaris blakei BENNETT*, K.C.*; EMLET, R.E.; YOUNG, C.M.; Oregon Institute of Marine Biology; Oregon Institute of Marine Biology; Oregon Institute of Marine Biology kbennet4@uoregon.edu

Extant urchins are divided into two lineages, the Cidaroida and the Euechinoidea. Cidaroida, the order of “pencil urchins,” is an ancient lineage and is thought to represent the primitive form of euechinoids. This study describes the embryonic and larval development through metamorphosis and into the juvenile stage of the bathyal cidaroid Cidaris blakei. Morphological features of C. blakei such as egg size, presence of an apical tuft, ectodermal invaginations at gastrula stage, an extended lecithotrophic stage prior to completion of the gut, and juvenile spine shape distinguish this species from other planktotrophic cidaroids. We compare the development of C. blakei to that of other cidaroids and also other deep-sea echinoids. We discuss which characteristics are common to cidaroids, and potentially attributable to phylogenetic constraints, and which adaptations may be specific to the deep-sea environment.