| rdfs:comment
| - Cnidaria is a class of animal that consists of the Jellyfishes. They were known to have been experimented on for T-virus research.
- Cnidaria () is a phylum containing some 9,000 species of animals found exclusively in aquatic, mostly marine, environments. Despite their early appearance in the evolutionary history of animals and their simple morphology, the modern forms are genetically sophisticated and bio-chemically complex. There are four main classes of Cnidaria:
* Class Anthozoa (anemones, corals, etc.)
* Class Scyphozoa (jellyfish)
* Class Cubozoa (box jellies)
* Class Hydrozoa (Obelia, Aequorea, Portuguese Man o' War, etc.)
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| abstract
| - Cnidaria () is a phylum containing some 9,000 species of animals found exclusively in aquatic, mostly marine, environments. Despite their early appearance in the evolutionary history of animals and their simple morphology, the modern forms are genetically sophisticated and bio-chemically complex. The unifying characteristic of the Cnidarians is the presence of cnidocytes (nematocytes), specialized cells that carry organelles called cnidocysts (nematocysts). It is widely accepted that all cnidarians inherited cnidocytes from a single common ancestor. As for the etymology, the word Cnidaria comes from the Greek word "cnidos", which means "stinging nettle". The corals, which are important reef-builders are placed in this phylum, along with sea anemones, jellyfish, sea pens, sea pansies and sea wasps. The name Coelenterata was formerly applied to the group, but as this name included the Ctenophores, it has been abandoned. Cnidarians are highly evident in the fossil records, having first appeared in the Ediacaran period. The basic body shape of a cnidarian consists of a sac containing a gastrovascular cavity with a single opening that functions as both mouth and anus. It has radial symmetry, meaning that whichever way it is cut along its central axis, the resulting halves would always be mirror images of each other. Their movement is coordinated by a decentralized nerve net and simple receptors. Several free-swimming Cubozoa and Scyphozoa possess rhopalia, complex sensory structures that can include image-forming eyes with lenses and retinas and a gravity-sensing statocyst comparable in function to the otolith of the vertebrate inner ear. Tentacles surrounding the mouth contain cnidocytes, specialized stinging cells, which they use to catch prey and defend themselves from predators. The ability to sting is what gives cnidarians their name. There are four main classes of Cnidaria:
* Class Anthozoa (anemones, corals, etc.)
* Class Scyphozoa (jellyfish)
* Class Cubozoa (box jellies)
* Class Hydrozoa (Obelia, Aequorea, Portuguese Man o' War, etc.) Traditionally the hydrozoans were considered to be the most primitive, but evidence now suggests the anthozoans were actually the earliest to diverge. Sea anemones, sea fans and corals are in this class. The non-anthozoan classes may be grouped into the subphylum Medusozoa. Under this scheme, Anthozoa is also elevated to a subphylum. Theoretically, members of Cnidaria have life-cycles that alternate between asexual polyps and sexual, free-swimming forms called medusae. In reality there is a vast variation within the life-cycles of cnidarians.
- Cnidaria is a class of animal that consists of the Jellyfishes. They were known to have been experimented on for T-virus research.
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