Urechidae

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

Family Urechidae

Description. Proboscis very much reduced. Distal part of mid-gut greatly enlarged and acts as a respiratory chamber, water entering and leaving it through the anus. Foregut very long and contains a gizzard. No sexual dimorphism.

Genus Urechis Seitz, 1907

Description. Longitudinal musculature of the body wall lies between an outermost layer of circular and innermost layer of oblique muscles which are fasciculated. Two ventral setae connected by a strong interbasal muscle and one circle of curved anal setae. Internally, paired dorso-ventral muscles present anterior to the setae. Blood vascular system is absent. Two to three pairs of gonoducts with gonostomal lips that are long and spirally coiled. Anus eccentrically placed in relation to posterior ring of setae. Anal vesicles are large sacs. Sexes are separate.