Sampling sites, feeding and copulation of Maritigrella crozieri . (A) Schematised map of the Florida Keys. Red asterisks indicate collection sites. (B) Adult M. crozieri wrapped around and feeding on a zooid of the ascidian Ecteinascidia turbinata. (C) A colony of E. turbinata growing on a mangrove root, lifted from the water. (D) Adult M. crozieri gliding on a colony of E. turbinata underwater. Parts (E) through (G) illustrate copulation. (E) Two adult M. crozieri with extended male copulatory organ (mco) gliding onto a third animal, with another specimen approaching from the right. (F) Single adult with fully extended mco; anterior is up. (G) Sperm deposition (white spots) on the dorsal side of another adult. Inset shows detail of the mco with two sperm deposits (see also Additional file 1).