Echiuridae

Biseswar, Ramlall, 2012, Zoogeography of the echiuran fauna of the East Pacific Ocean (Phylum: Echiura), Zootaxa 3479, pp. 69-76 : 72

Family Echiuridae

Description. Echiurans without sexual dimorphism. Proboscis well developed but never bifid. Trunk sausageshaped, usually covered with papillae. Longitudinal muscles in some genera thickened to form bands and oblique musculature between longitudinal muscle bands may or may not form bundles. Gonoducts paired, usually 1–3 pairs. Gonostome basal in position except in one genus and gonostomal lips may be fan or leaf-like, elongate and spirally coiled. A pair of ventral setae present in all genera (except in one species where numerous spinelets present instead). Interbasal muscle between setae may or may not be present. Anal setae and post-pharyngeal diaphragm present only in Echiurus . Dorsal and neuro-intestinal vessels usually connected by intestinal ring sinus at posterior end of foregut. Anal vesicles usually elongated, blind-ending tubes or sac-like but never branched; their surface usually covered with small, ciliated funnels.