SYNOPTIC DESCRIPTION OF THE PHYLUM CHAETOGNATHA

SYNOPTIC DESCRIPTION OF THE PHYLUM CHAETOGNATHA (LEUCKART 1854)

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PHYLUM CHAETOGNATHA LINKS

The following information came from Margulis and Schwartz (1998), Buchsbaum (1938), Barnes (1980), Barnes (1984), Brusca and Brusca (2003), Hickman (1973), Storer and Usinger (1965), Colbert and Morales (1991), Pecenik (2005), Nielsen (2001), and Tudge (2000).

I. SYNONYMS: arrow worms.

II. NUMBER: >100 species known.

II. PHYLUM CHARACTERISTICS:
- A. Structure
  - Symmetry: Bilateral; body divided into head, trunk, and post anal tail, all separated by septa.
  - Body Cavity: Eucoelomate; enterocoelic (text with tooltip) but without a peritoneum. One chamber in the head, two in the trunk, and one (+) in the tail.
  - Body Covering: Covered by thin chitinless cuticle (text with tooltip) .
  - Support: Hydrostatic skeleton.
  - Digestive System: Head with a large chamber bearing 4-14 large spines that help to grasp prey (Figure B). Simple tube with a muscular pharynx, two diverticula, and a ventral anus just anterior to the tail septum.
  - Circulatory System: Absent.
  - Locomotion: Active swimmer with nonmuscular fins.
  - Excretory System: Absent.
  - Nervous System: Circumpharyngial ring with a cerebral ganglion; anterioventral trunk ganglion (text with tooltip) and several lateral ganglia; sense organs include one pair of eyes, hair fans that detect vibrations and a ciliary loop on the dorsal region of the head and neck.
  - Endocrine System:
  - Respiratory System: Direct absorption through the skin.
- B. Reproduction:
  - Reproductive System: Hermaphroditic. One pair of ovaries in front of the tail septum and a pair of testes (text with tooltip) behind the septum. Copulation occurs (self-fertilization possible).
  - Development: Eggs cleave radially. Direct development.
- C. Ecology: Free-swimming marine predators.

LITERATURE CITED

Barnes, R. D. 1980. Invertebrate Zoology. Saunders College/Holt, Rinehart and Wilson, Philadelphia.

Barnes. R. S. K. 1984a. Kingdom Animalia. IN: R. S. K. Barnes, ed. A Synoptic Classification of Living Organisms. Sinauer Associates, Inc., Sunderland, MA. pp. 129-257.

Brusca, R. C. and G. J. Brusca. 2003. Invertebrates. Sinauer Associates, Inc. Sunderland, Mass.

Buchsbaum, R. 1938. Animals Without Backbones, An Introduction to the Invertebrates. The University of Chicago Press. Chicago.

Dunn, C.W., A. Hejnol, D.Q. Matus, K. Pang, W.E. Browne, S.A. Smith, E. Seaver, G.W. Rouse, M. Obst, G.D. Edgecombe, M.V. Sørensen, S.H.D. Haddock, A. Schmidt-Rhaesa, A. Okusu, R.M. Kristensen, W.C. Wheeler, M.Q. Martindale, and G. Giribet. 2008. Broad phylogenomic sampling improves resolution of the animal tree of life. Nature. 452: 745-749.

Hickman, C. P. 1973. Biology of the Invertebrates. The C. V. Mosby Company. Saint Louis.

Margulis, L. and K. Schwartz. 1998. Five kingdoms, an illustrated guide to the phyla of life on earth. 3rd Edition. W. H. Freeman and Company. New York.

Meglitsch, P. A. and F. R. Schramm. 1991. Invertebrate Zoology. Oxford University Press, New York, Oxford.

Nielsen, C. 2001. Animal Evolution: Interrelationships of the Living Phyla. 2nd Edition. Oxford University Press. Oxford.

Ruppert, E. E. and R. D. Barnes. 1994. Invertebrate Zoology. 6th edition. Saunders. Ft Worth, TX.

Ruppert, E. E., R. S. Fox, and R. D. Barnes. 2004. Invertebrate Zoology: A Functional Evolutionary Approach. Seventh Edition. Thomson, Brooks/Cole. New York. pp. 1-963.

Storer, T. I. and R. L. Usinger. 1965. General Zoology. 4th Edition. McGraw-Hill Book Company. New York.

Tudge, C. 2000. The Variety of Life, A Survey and a Celebration of all the Creatures That Have Ever Lived. Oxford University Press. New York.

Valentine, J. W. 2004. The Origin of Phyla. University of Chicago Press. Chicago. 614 pp.

By Jack R. Holt and Carlos A. Iudica. Last revised: 01/29/2012

SYNOPTIC DESCRIPTION OF THE PHYLUM CHAETOGNATHA (LEUCKART 1854)

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