title: Morphological evidence of depth-related speciation in deep-sea Arctic echinoderms
abstract: Three eurybathic cosmopolitan genera of echinoderms, the holothurians Elpidia, the stalked crinoids Bathycrinus and the echinoids Pourtalesia, are widely distributed in the deep Arctic Ocean. The genera Echinus and Gracilechinus occur in the Arctic only in the near-Atlantic sector of the basin. In all the five genera, there is a pronounced difference in morphology between specimens occurring at different depths. It is suggested that these differences reflect the depth-related speciation that too
journal: Invertzool