Phylum Cnidaria

Body structure

1 body opening, radial symmetry, 2 cell layers that form tissues

Class Scyphozoa

All jellyfish except the box jellies, medusa stage is the dominant body form

Class Cubozoa

All the box jellyfish, name comes from the boxlike form of the medusa shape, stings can be fatal to humans

Polyp

Body for of Cnidarians that consists of a tube shape with tentacles surrounding the mouth

Medusa

Body form that consists of an umbrella shape with tentacles hanging down with the mouth between the tentacles

Nematocysts

Capsule in the Cnidocytes that holds a coiled, threadlike tube containing poison and barbs that are discharged to capture prey or defend the cnidarian

Reproduction

External fertilization, consists of sexual and asexual reproduction

Corals

Live as colonies, secrete protective calcium carbonate shelters around their soft bodies, living portion of the reef is the thin, fragile layer growing on top of the shelters lefts by others

Sea anemones

Live as individual animals, form symbiotic relationship with some animals, like the clownfish

Nerve net

Nervouse system, sensory structures that conduct impulses to and from all parts of the body to respond to stimuli

Cnidaria

Phylum name for Cnidarians, means "stinging cells"

Class Anthozoa

Sea anemones and corals, ~6200 species, polyp is the dominant body form

Gastrovascular cavity

Space surrounded by the inner cell layer that functions as a gut, cells inside this area release enzymes to aid in digestion

Cnidocytes

Stinging cells located on the tentacles

Class Hydrozoa

~2700 species, have both polyp and medusa stages in the life cycle, most form colonies, include the Portuguese Man of War and hydra