Animal Phyla/Acanthocephala




 * Acanthocephala
 * Name Meaning: Thorny head
 * English Common Name: Thorny-headed worms
 * Major distinguishing characteristics: Reversible spiny proboscis
 * Approximate number of species described: 1,151

Natural History
All known Acanthocephalans are intestinal parasites of vertebrates. Some spend their early development as parasites of invertebrates, but must move to a vertebrate host in order to reproduce. They are most commonly found in fishes, but may be found in any type of vertebrate. They lodge by their "thorny" (spine covered) proboscis into the intestinal wall of their host. They ingest directly through their body wall.

Taxonomy
There are over 1,100 species described, in four Classes.

The four Classes are
 * Archiacanthocephala
 * Eoacanthocephala
 * Palaeacanthocephala
 * Polyacanthocephala

Anatomy
Acanthocephala are a simple tubular worm with a spiny or "thorny" proboscis, which they use to embed themselves into the intestinal wall of their host.

The Fossil Record
There is no fossil record of Acanthocephala. They are soft bodied, and as internal parasites it would be a very rare thing for one to become fossilized.

Quiz

 * /Acanthocephala Quiz/

References and Further Reading

 * Acanthocephala at Encyclopedia of Life
 * Acanthocephala at Tree of Life
 * Classification of the Acanthocephala
 * Labandeir, Conrad C. Paleobiology of Predators, Parasitoids, and Parasites: Death and Accomodation in the Fossil Record of Continental Invertebrates. in Kowalewski, M., and P.H. Kelley, (eds.), 2002. The Fossil Record of Prédation. Paleontological Society Papers, 8: 211-249. Available online at The Smithsonian Institution