Image Key > Cnidaria > Hydrozoa > Hydroidomedusae
Hydroidomedusae Bouillion, Boero, Cicona, Gili and Hughes 1888Select from one of the following Subclasses:
Taxonomy
| Phylum |
Cnidaria |
| Superclass |
Hydrozoa |
| Class |
Hydoidomedusae |
Size
- Generally small, around 5-60 mm diameter.
Distinguishing characteristics
- Variable shape.
- Tentacles are always present usually around the lower margin of the bell.
- Mouth positioned on a tube-like manubrium.
Distribution
Ecology
- Many hydromedusae have a benthic, sessile stage (polyp) in their life history, but only the pelagic medusa can be caught in plankton nets and so is described here.
- Hydrozoans can be found in both marine and freshwater habitats.
- Characteristically, the polyp and medusa stages alternate in the life cycle; the polyp reproduces asexually while the medusa reproduces sexually.
- Hydrozoans are closely related to scyphozoans (‘jellyfish’) but, in the latter group, the medusa phase is often large and is dominant in the life cycle.
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