Description of a free-living Polychaete without gut: Astomus taenioides n.gen., n.sp. (Protodrilidae, Archiannelida)

Publisher Website
Google Scholar
Abstract
A new protodrilid is described, that lives in the coral sands of the Island of Moorea (French Polynesia). ASTOMUS taenioides gen. et sp. nov. has no gut, mouth, anus, pharyngeal bulb or salivary glands. A thin median cord of cells rich in refringent granules takes the place of a gut and probably represents an endodermal vestige and a stocking location for reserve substances. The surface of the epidermis is increased due to an enlargement of the segments into lateral lobes; cilia are abundant and the cuticle well developed. These characteristics might favor considerable exchanges between the organism and its surroundings. The absorption of dissolved organic substances, well known in other maring invertebrates, seems to be developed in this case to the point that this annelid, like the pogonophores, can survive without any gut. If, compared with Annelida, the principal trait of the Pogonophora is the absence of a gut and the absorption of nutritive elements solely through the epidermis, the consequence of the discovery of this Protodrilidae is to eliminate the last barrier separating Pogonophora from Annelida.