Fig. 1. Morphological organization of sea pansy colonies with emphasis on water circulation. (A) Schematic diagram of the upper surface of the discoid colony showing the distribution of water polyps (siphonozooids, shown in green) and the direction of water flow in the channels beneath the polyps (arrows). Water from the channels and the peduncle reaches the axial canal and moves forward to the large exhalent siphonozooid (boxed region, shown in B) where it is ejected. The triangle shaded in blue represents the area excised for reduced preparation recording. Syringe symbols represent site and orientation of drug (left) and vehicle (right) injections for behavioural experiments. The autozooids (feeding and reproductive polyps) are not represented for better clarity. (B) Photomicrograph of area corresponding to the boxed region in A, from a living colony. Note the autozooid, the miniature inhalent siphonozooids (small arrows) and the single exhalent siphonozooid (large arrow) in which the eight septa irradiating from the mouth opening are typical of the octocorallian body organization. Note also the masses of spicules (shown in violet) forming the calcified skeleton of the colony.