Cnidarians
- Hydra, jellyfish, coral, sea anemone
- Invertebrate
- Radial symmetry
- Central mouth
- Polyp or medusa body plan
- Life cycle: some go through a planula larva (free-swimming) stage and then go through reproduction.
- Asexual reproduction (budding): polyp
- Sexual reproduction: medusa
- Have two cell layers: ectoderm and endoderm that is connected by mesoglea
- Have a gastrovascular cavity where extracellular digestion takes place
- Intracellular digestion occurs inside body cells and is carried out in lysosomes
- Have no transport system- every cell is in contact with the environment
- Have stinging cells: cnidocytes
- No central nervous system or head- have interconnected nerve cells
- No circulatory system, heart, or blood
- Usually have no skeletal material, but hard coral polyps build calcium carbonate structures around themselves