Corallimorpharia

Order Corallimorpharia

Anthozoa occurring in shallow and deep seas. Deep-sea forms solitary; most shallow-water forms clonal, undergoing asexual reproduction by longitudinal fission or pedal laceration. Zooxanthellae present or absent. Consistency soft or rigid, depending on thickness of mesoglea; mucus copious. Base flattened, usually adherent in shallowwater forms, may be unattached in deep-sea ones; lacks basilar muscles. Column smooth; without vesicles, verrucae, or spherules; rarely divisible into scapus and scapulus; may have weak longitudinal muscles. No marginal sphincter muscle or a weak, diffuse, endodermal one. Oral disc can be withdrawn or not. Tentacles generally not retractile; simple or branched; a simple tentacle may have an acrosphere at its distal end. Only one tentacle communicates with each exocoel; multiple tentacles may communicate with each endocoel; tentacles radially and cyclically arrayed. Longitudinal muscles of tentacles and radial muscles of oral disc usually weak, ectodermal. Actinopharynx short, with deep longitudinal folds; siphonoglyphs weakly developed or absent. Mesenteries commonly irregularly arranged; complete mesenteries usually numerous, directives present or absent. Retractor and parietobasilar muscles weak. Gametogenic region of mesenteries at the same level as the filaments. Mesenterial filaments with cnidoglandular tract only. Holotrichous nematocysts typically numerous; spirocysts may be rare or absent. Cnidom: spirocysts, holotrichs, microbasic b- mastigophores, and microbasic p -mastigophores.