SYNOPTIC DESCRIPTION OF THE PHYLUM RHOMBOZOA
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RHOMBOZOA LINKS
| The following information came from Margulis and Schwartz (1998), Barnes (1980), Barnes (1984), Brusca and Brusca (2003), Hickman (1973), Storer and Usinger (1965), Valentine (2004), and Tudge (2000). |
I. SYNONYMS: dicyemids, rhombozoans, mesozoans.
II. NUMBER: >65 species known.
III. PHYLUM CHARACTERISTICS:
- A. Structure
- Symmetry: Bilateral
- Body Cavity: Not present.
- Body Covering: Ciliated epithelium.
- Support: None.
- Digestive System: None.
- Circulatory System: None.
- Locomotion: Ciliated epithelium.
- Excretory System: None.
- Nervous System: None.
- Endocrine System: None.
- B. Reproduction:
- Reproductive System: Dioecious animals release eggs or sperm. Dicemids produce flagellated, planktonic larvae.
- Development: Young cephalopods infected by infusiform larvae (text with tooltip) Infusiform larvae develop from axoblasts of sexual vermiform adults. These axoblasts form infusorigens, multicellular larvae with an inner mass of sperm surrounded by eggs. The zygotes thus produced develop into ciliated infusiform larvae. The infusiform is the dispersive stage. It leaves the kidney with the urine. How the cycle is completed and they return to another adult cephalopod is a mystery. which migrate to kidney and develop into adult while the cephalopod is a juvenile. Axoblast (text with tooltip) Axoblasts are rhombozoan reproductive cells that occur within the Rhombozoan axial cell. They each develop into vermiform larvae within the axial cell. cells produce vermiform larvae that develop into nematogens which multiply asexually; when population densities become high, nematogens produce rhombogens which produce gametes that are fertilized within the axial cell. Zygotes develop into infusiform larvae which leave the rhombogen and the cephalopod.
- C. Ecology: Parasites (text with tooltip) A parasite is a symbiotic organism that benefits from the relationship at the expense of the host. of marine invertebrates, particularly cephalopod mollusks.
| 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., 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. Walker, J. C. and D. T. Anderson. 2001. The Platyhelminthes, Nemertea, Entoprocta, and Gnathostomulida. In: Anderson, D.T., ed. Invertebrate Zoology. Oxford University Press. Oxford, UK. pp. 59-85. [L] Valentine, J. W. 2004. The Origin of Phyla. University of Chicago Press. Chicago. 614 pp. |
| By Jack R. Holt. Last revised: 01/26/2012 |
