< Animal Phyla

Animal Phyla/Acanthocephala

An Acanthocephalan, Macracanthorhynchus hirudinaceus, adult.
  • Acanthocephala
  • Name Meaning: Thorny head
  • English Common Name: Thorny-headed worms
  • Major distinguishing characteristics: Reversible spiny proboscis
  • Approximate number of species described: 1,420

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 "horny" (spine covered) proboscis into the intestinal wall of their host. They ingest directly through their body wall.

Taxonomy

There are over 1,400 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

While no adult specimens of acanthocephalans have been found in the fossil record, their eggs have been recorded as far back as the Cretaceous.

Quiz

References and Further Reading

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