| Keywords |
Cnidaria [WoRMS]
Marine/Coastal |
| Authors | | Top |
- Berzins, I.K.
- Yanong, R.P.E.
- LaDouceur, E.E.B.
- Peters, E.C.
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| Abstract |
The phylum Cnidaria contains an estimated 11 000+ living species and is almost exclusively an aquatic group, primarily marine but with some freshwater species and a few terrestrial parasitic species. Cnidarians reproduce both sexually and asexually, most species incorporating both methods. They produce gametes (eggs and sperm), can be monoecious, producing both eggs and sperm, or dioecious, with individuals of separate sexes (gonochoric). Cnidarians are soft-bodied, diploblastic (two cell layers) metazoans (animal kingdom), with primary radial symmetry (although with some variations). Threats to cnidarians include climate change, infectious diseases, development of shorelines, increase in surface runoff, land-based sources of pollution, ship groundings, and damaging fishing techniques (dynamite, nets, etc.). As a possible indicator of some of these detrimental changes, there has been an increase in the frequency of jelly blooms. |
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