A new ciliary feeding structure in an ophiuroid echinoderm.

The genital shields which form the walls of the bursal slits in Ophiura texturata are covered by a precisely oriented arrangement of ciliated ridges and non-ciliated grooves. An electron microscopic examination has revealed many mucous cells associated with this structure and a catecholamine-containing nerve plexus underlying it. An examination of the currents produced by this ciliated structure suggest that it is associated with suspension feeding and preliminary results indicate that the secretion of mucus is under neural control. Specialized structures of this type have not been previously described in ophiuroids and are only present in the members of certain families. The interest in these structures is not just in relation to feeding mechanisms in ophiuroids but they also provide a useful specialized preparation for the study of some aspects of the function of the subepidermal nerves in echinoderms.