Cnidaria



Home Page of the phylum Cnidaria, the major group of invertebrates that includes the sea anemones, corals, jellyfishes, hydroids, and animals that contain 'cnida' stinging capsules.

Photograph by Steve Barker

Compass Jellyfish, Chrysoara hysoscella


Cnidaria

Greek  knide  = nettle

Radially symmetrical animals with a simple form, all with stinging capsules. These capsules are activated when chemically or mechanically stimulated. Species appear as polyps (sea anemones) or medusa (jellyfish), and often a species goes through both forms in its life cycle (jellyfish, hydroids). Cnidarians live in the sea except for a few (e.g. hydra) that inhabit fresh water.


British Coelenterate Society

1999 Meeting


Anthozoa

Class Alcyonaria (Octocorallia): Soft Corals, Sea Fans, Sea Pens.

Class Zoantharia (Hexacorallia): Corals, Sea Anemones.

Sea Anemones 
 

The stinging capsules in the tentacles and other parts of the sea anemone are called cnidae. The commonest type are called nematocysts. These capsules can be seen under the microscope and their mechanism is arguable the fastest action in the whole of the animal kingdom. The fluid filled capsule called the nematocyst everts and forces the filament to discharge venom into its prey of smaller organisms.

Worldwide Cnidaria Web Site


Aequorea
Biomar Sea Anemones and other Anthozoa
Cnidaria Newsgroup
Dead Men's Fingers  Alcyonium digitatum
Devonshire Cup Corals
Hydrozoan Society
Jellyfish (British species)
Norwegian Deep Water Corals
Corals of the Abyss (NE Atlantic)
Reef-forming Cold-water Corals
Moon Jellyfish

IMAGES  on flickr

Cnidaria of the NE Atlantic on facebook

Images of British Cnidarians
Cnidarians of the World
Sea Anemones
Jellyfish

Jellywatch
Jellyfish Blooms



 
 



CLAUDIA E. MILLS
http://faculty.washington.edu/cemills/
Ctenophores
http://faculty.washington.edu/cemills/Ctenophores.html
Hydromedusae
http://faculty.washington.edu/cemills/Hydromedusae.html

Hermit Crab with Calliactis
Cnidarian Research Institute
Cnidaria (University of Michigan)
Cnidaria Web Site

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