Phylum Cnidaria

Body with no head and no segmentation.
Body wall two layered: external epidermis and inner gastrodermis, jelly-like, non-cellular mesogloea in between.
Cnidoblasts (stinging cells) present, help to catch prey (carnivorous)
Skeleton calcareous, horny or none.
Asexual reproduction by budding in the sessile (polyp) stage, and sexual reproduction in free swimming (medusa) stage.
Radial symmetry
All marine, except Hydra (found in fresh water)
Either fixed like hydra, sea-anemones and corals, or free floating like the jelly fish.