SYNOPTIC DESCRIPTION OF THE PHYLUM NEMERTEA
| EUKARYA> UNIKONTA> OPISTHOKONTA> ANIMALIA> METAZOA> BILATERIA> PROTOSTOMATA> SPIRALIA> TROCHOZOA> EUTROCHOZOA> NEMERTEA |
NEMERTEA 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), Tudge (2000), and Walker and Anderson (2001). |
I. SYNONYMS: ribbonworms, rhynchocoels, nemertines.
II. NUMBER: >900 species known.
III. PHYLUM CHARACTERISTICS:
- A. Structure
- Symmetry: Bilateral
- Body Cavity: Not present. 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. . Evertible proboscis (text with tooltip) An evertible proboscis is a proboscis that can be extended usually by hydrostatic muscular contraction. in a cavity called a rhynchocoel (text with tooltip) A rhynchocoel is a fluid-filled body cavity (coelom? pseudocoelom?) into which the nemertene evertible proboscis retracts. , dorsal to the intestine.
- Body Covering: Ciliated epithelium.
- Support: Hydrostatic skeleton.
- Digestive System: Complete food tube with mouth and anus. Captures food with an evertible proboscis, often armed with a stylet at the tip.
- Circulatory System: Blood vessel system in parenchymal mesoderm.
- Locomotion: Ciliated epithelium and muscular contractions.
- Excretory System: Specialized excretory canals.
- Nervous System: Anterior ganglion (text with tooltip) A ganglion (ganglia, pl.) is a cluster of nerve cells. A brain is an enlarged ganglion. with 2 major lateral nerves.
- Endocrine System: None.
- B. Reproduction:
- Reproductive System: Most are dioecious (text with tooltip) Dioecious organisms have separate male and female individuals. . Oviparous (text with tooltip) An oviparous (adj.) animal is one that releases eggs in its life cycle. They may be fertilized internally or externally. .
- Development: Zygote develops into pilidium (text with tooltip) A pilidium is a ciliated, planktonic larval form of some Nemertinea. It has an apical tuft of cilia and is helmet-shaped. or desor larva with a flatworm-like gut.
- C. Ecology: Freshwater, marine, or terrestrial. Some are commensals (text with tooltip) A commensal is a symbiotic organism that benefits from the symbiosis without harming the host. or parasites. Usually carnivores. Marine species are usually benthic (text with tooltip) A benthic (adj.) organism is one that lives in or on the bottom of marine or freshwater environments. .
| 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: 01/25/2012 |
