| Popis: |
There are 10,000+ species in the phylum Cnidaria, and the vast majority occur in marine systems. Examples include hydroids, true jellyfish, sea anemones and corals. Of the six proposed taxonomic classes in the phylum Cnidaria, only 2 classes Polypodiozoa and Hydrozoa, contain freshwater genera. Class Polypodiozoa is represented by an endoparasite while the class Hydrozoa has more familiar and prevalent members such as Hydra as well as the less familiar but intriguing freshwater jellyfish. Some of the life cycles of freshwater cnidarians have both diagnostic stages of the polyp and medusa while others only exist as the polyp stage. Both stages are often inconspicuous but can be found in various types of freshwater habitats such as ponds, rivers and lakes. |
