Cnidaria
From Microcosm Aquarium Explorer
- Acropora monticulosa, Digitate Stony Coral. Scott W. Michael
- Feathery hydroids, capable of delivering a powerful sting. Scott W. Michael
- Cassiopeia xamachana, Mangrove Upsidedown Jellyfish. Janine Cairns-Michael
- Heteractis magnifica, Magnificent Sea Anemone. Scott W. Michael
- Protopalythoa spp., Zoanthids Scott W. Michael
[edit] The Cnidarians
Hydras, Jellyfishes, Sea Anemones, Corals
Number of Living Species: more than 9,000, mostly marine.
Common Characteristics: radial symmetry; a gutlike gastrovascular cavity (coelenteron) with a common mouth/anus; tentacles surrounding the mouth aid in the capture of food; tentacles armed with stinging structures known as nematocysts; two predominant body forms: the sessile polyp, such as the corals, and the free-swimming medusa, such as the jellyfishes.
Noteworthy Behaviors: all are carnivorous, feeding on plankton of various types and sizes; many have symbiotic zooxanthellae embedded in their tissues that provide an important source of energy; some, especially members of the Classes Hydrozoa, Cubozoa, and Scyphozoa, can deliver painful or even fatal stings to humans; those that secrete calcium carbonate (especially the stony corals) are primary contributors to coral reef formation.
[edit] Hydroids
Class Hydrozoa (Hydrozoans, Hydroids, Hydrocorals): 2,700 species
[edit] Jellyfishes
Class Scyphozoa (Jellyfishes): 200 species
[edit] Corals and Anemones
Class Anthozoa (Sea Anemones, Stony Corals, Soft Corals, Zoanthids, Gorgonians, Sea Pens, Sea Pansies): 6,000 species
From: Reef Life by Denise Nielsen Tackett