ABSTRACT
Cystidean larvae are metarnorphic crinoid larvae that develop soon after competent doliolariae attached onto the substrate. Competent doliolariae of Antedon bifida typically have an anterior attachment complex. Fixed doliolariae metamorphose in pedunculate cystideans whose attachment disk is homologous to the doliolaria attachment complex. Investigations on cystidean disks showed that the epidermis strikingly modifies in structure (viz. from columnar to almost squamous) and that its constituting cells change from tall glandular to flat support-like cells. Moreover, there is a total regression of the nerve plexus that was associated to the attachment complex of the doliolariae.
