25 January 1991
Vol 251, Issue 4992

About The Cover

Adult reef-building marine polychaetes (Phragmatopoma lapidosa californica) that have built sand tubes against a pane of glass. Planktonic larvae of these worms settle when they contact adult tube sand, a response that is facilitated by chemical and hydrodynamic processes. See page 421. [Photograph by Joseph R. Pawlik, University of North Carolina at Wilmington]