Aspidogastrea

Synonym

Aspidobothrea.

Classification

Class of Platyhelminthes.

General Information

The Aspidogastrea is a relatively small group, which is characterized by a very large hookless holdfast organ (ventral or Baer&s disc, opisthaptor), which, in adult worms, covers nearly the whole ventral side (Fig. 1A). The Aspidogastrea are typically endoparasites of many molluscs, elasmobranchs, teleosts, turtles, or decapod crustaceans (Table 1) and are not host-specific. Their development occurs as metamorphosis via larval stages (Fig. 1B, C); in general no intermediate host is needed; however, larvae may continue their development in different hosts. With respect to host specificity, their parasitism is apparently not very specialized, since it is not uncommon to find an aspidogastrean in the gut of a fish, although it may normally parasitize a mollusc.

Figure 1 A–C

Life cycle stages of Aspidogastrea (seen from ventral side). A, B. Aspidogaster conchicola . A. Adult worm (2–3 mm long) from kidney...