Key Characteristics of Phylum
How Many Species in Phylum?
9,000
Structure and Function
- Basic body plan - A sac with a central digestive compartment (called the gastrovasular cavity)
- Two possible body plans
- Polyp - a cylindrical form that attaches to something by the aboral end of the body and extends tentacles around the oral end
- Medusa - a flattened, oral opening down, bell-shaped; moves freely in the water, tentacles dangle from the oral surface pointing downward
- Some can be both polyp and medusa in their life
- Cnidarians are radially symmetrical
Habitat
- Aquatic Environments
- Inhabit all depths
- Found from the Great Barrier Reef to the Arctic Ocean and everywhere in between