Gnathifera

Abstract

The taxon Gnathifera was erected based on morphological data by Ahlrichs (1995, 1997). The taxon comprises the Gnathostomulida and Syndermata (which unites Rotifera, Acanthocephala, Seisonida) (Fig. 1.1). With the discovery of Limnognathia maerski (Kristensen and Funch 2000), the taxon Micrognathozoa has been included into the Gnathifera. The name Gnathifera is based on the presence of a complex jaw apparatus in the pharynx of all groups, except Acanthocephala (Sørensen 2003; Funch et al. 2005). Gnathifera are tiny, bilaterally symmetric animals that live in aquatic habitats. Only the parasitic acanthocephalans reach body lengths of up to 80 cm. The acanthocephalans have lost many morphological characters as adaptations to their parasitic lifestyle, including the jaw apparatus and the digestive tract.