Pomphorhynchus in the rectum of a blue fish ( Pomatomus saltatrix )

  • Echinorhynchida
  • Polymorphida

The Palaeacanthocephala are a class of scratch worms with mandatory change of host, the parasites than adult intestinal parasites in different groups of vertebrates such as fish, amphibians, birds and mammals and usually have aquatic life cycles. There are small to medium-sized species with average body lengths of a few centimeters.


As anatomical features, the main channels of the Lakunensystems at the Palaeacanthocephala are at your sides and not, as in the Archiacanthocephala dorsal and ventral. Protonephridia are not present.

The males have two to eight cement glands and only a few nuclei in syncitialen ligament. In females, only a ligament sac is present, which emerged from an amalgamation of the original two sacks. With puberty, the walls of the bag are dissolved and the eggs are placed in the body cavity, where they float freely.

Way of life

The Palaeacanthocephala in most cases a aquatic life cycle. The definitive hosts are mainly fish, but also amphibians, water birds or seals come as hosts in question. As intermediate hosts the animals use mainly small crustaceans such as amphipods and isopods different.


The following are the orders and families of Palaeacanthocephala, as well as some selected genera are listed:

  • Pomphorhynchus
  • Centrorhynchidae
  • Plagiorhynchidae
  • Polymorphidae Corynosoma
  • Filicollis
  • Polymorphus


Cited evidence

The information in this article originate for the most part the limits given in literature sources, in addition, the following sources are cited: