SYNOPTIC DESCRIPTION OF THE PHYLUM GNATHOSTOMULIDA (AX 1956)
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GNATHOSTOMULIDA 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), and Tudge (2000). |
I. SYNONYMS: gnathostomes.
II. NUMBER: >80 species known.
III. PHYLUM CHARACTERISTICS:
- A. Structure
- Symmetry: Bilateral
- Body Cavity: Some disagreement. May be present but highly reduced. Organ systems in parenchymatous mesoderm (text with tooltip) Parenchymatous mesoderm is connective tissue that fills the space between the musculature and the gut in acoelomates. .
- Body Covering: Ciliated epithelium (Figure A). Each epidermal cell with only one flagellum.
- Support: Hydrostatic skeleton.
- Digestive System: Blind, tubular gut. Muscular pharynx with paired jaws (Figure B) and hard comb-like basal plate (text with tooltip) A basal plate is a characteristic component of the 'jaw' mechanism of a gnathostomulid. It lies within the mouth, anterior to the 'jaws' at the entrance to the pharynx. .
- Circulatory System: Absent.
- Locomotion: Ciliated epithelium and muscular contractions.
- Excretory System: ?
- Nervous System: Some concentration of nervous tissue toward the anterior end.
- Endocrine System: None.
- B. Reproduction:
- Reproductive System: Males, females and hermaphrodites. Internal fertilization. Oviparous.
- Development: Zygote develops by spiral cleavage; no larval stage.
- C. Ecology: Marine, inhabit interstitial and detrital habitats.
| 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. Giribet, G., D. L. Distel, M. Polz, W. Sterrer and W. Wheeler. 2000. Triploblastic relationships with emphasis on the acoelomates and the position of Gnathostomulida, Cycliophora, Plathelminthes, and Chaetognatha: a combined approach of 18S rDNA sequences and morphology. Systematic Biology 49:539-562. Giribet, G., C. W. Dunn, G. D. Edgecombe, and G. W. Rouse. 2007. A modern look at the Animal Tree of Life. Zootaxa. 1668: 61-79. 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 |
