Bennett Kathleen C, Young Craig M, Emlet Richard B
Oregon Institute of Marine Biology and the Department of Biology, University of Oregon, Charleston, OR 97420, USA.
Biol Bull. 2012 Apr;222(2):105-17. doi: 10.1086/BBLv222n2p105.
Cidaroids, one of the two major sister clades of sea urchins, first appeared during the lower Permian (ca. 270 mya) and are considered to represent the primitive form of all living echinoids. This study of Cidaris blakei, a deep-sea cidaroid urchin with planktotrophic larvae, provides a description of development from fertilization through early juvenile stages and is the first report of a deep-sea urchin reared through metamorphosis. C. blakei resembles other cidaroids in its lack of a cohesive hyaline layer, the absence of an amniotic invagination for juvenile rudiment formation, and the presence of spines with a single morphotype at metamorphosis. C. blakei differed from other cidaroids in the presence of an apical tuft, the extent of fenestration of postoral skeletal rods, the shape of juvenile spines, and an extended (14-day) lecithotrophic stage prior to development of a complete gut. The development of C. blakei, 120 days from fertilization to metamorphosis, was protracted relative to that of shallow-water cidaroids. Preliminary work on temperature tolerances suggests that C. blakei larvae would be unable to survive the warmer temperatures higher in the water column and are therefore unable to vertically migrate.
海胆的两个主要姐妹进化枝之一的刺海胆目，最早出现在二叠纪早期（约2.7亿年前），被认为代表了所有现存海胆类的原始形态。对具有浮游生物摄食性幼虫的深海刺海胆目布莱克海胆的这项研究，描述了从受精到幼体早期阶段的发育过程，并且是关于通过变态发育饲养深海海胆的首次报告。布莱克海胆在缺乏粘性透明层、没有用于幼体原基形成的羊膜内陷以及在变态时有单一形态类型的刺等方面与其他刺海胆目相似。布莱克海胆在具有顶簇、口后骨骼棒的开窗程度、幼体刺的形状以及在完整肠道发育之前有一个延长的（14天）卵黄营养阶段等方面与其他刺海胆目不同。布莱克海胆从受精到变态发育的120天过程相对于浅水刺海胆目来说是延长的。关于温度耐受性的初步研究表明，布莱克海胆幼虫无法在水柱中较高位置的温暖温度下存活，因此无法垂直迁移。
