Phylum Acanthocephala

(spiny headed worms)
Major Attributes:
  1. Parasitic.
  2. Separate sexes; sexual dimorphism present.
  3. Body comprised of proboscus, neck and trunk.


Acanthocephala consists of the three classes Archiacanthocephala, Eoacanthocephala, and Palaeacanthocephala. All members are bilaterally symmetrical and cylindrical in shape. The adults live in the intestines of vertebrates and the larvae (acanthor) live in the tissues of crustaceans and insects. The body is composed of a neck, a long trunk and a proboscus which bears retractible hooks. The body plan is pseudocoelomic with no apparent digestive tract, although a flame bulb system is evident. The body wall is made of a cuticle and thick syncitial hypodermis with circular and longitudnal muscle fibers. The adult male has a full complement of reproductive organs and the female has only a large number of eggs.

Some Interesting Facts:

Lab Directions:
There are two slides (wm) and preserved specimens. What are the similarities between this phylum and the nematodes? One major difference is at the anterior end of the animal. Make a sketch of the whole animal and an exploded sketch of the anterior end. Is this structure similar or different to equivalent structures in the cestodes?
Pertinent Books Found in Lamson Library:
  1. Parker, Sybil P. 1982. Synopsis and Classification of Living Organisms. New York: McGraw Hill Company.
  2. Pennak, Robert W. 1964. Collegiate Dictionary of Zoology. New York: Ronald Press Company.

(Michele L. Cote, Fall 1994; edited B. Miller Spring 1995)