Echiuridae

Biseswar, Ramlall, 2009, The geographic distribution of echiurans in the Atlantic Ocean (Phylum Echiura), Zootaxa 2222, pp. 17-30 : 21

Family Echiuridae

Description. Echiurans without sexual dimorphism. Proboscis usually well developed but never bifid. Trunk cylindrical or sausage-shaped, usually covered with papillae. Longitudinal musculature 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 neurointestinal vessels usually connected by ring sinus at posterior end of foregut. Anal vesicles usually paired, elongated, blind-ending tubes or sac-like but never branched; their surface usually covered with small, ciliated funnels.