Cnidaria
Cnidaria
EOL Text
The predators of corals include certain species of fish, gastropods, and sea stars. Jellyfish don’t have many predators, but among them are ocean sunfish, marine turtles, and some humans.
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Sexual and asexual reproduction are common among cnidarians, and there are many species that can reproduce via both methods. Asexual reproduction occurs by cloning and includes budding, fragmentation, and fission. Sexual reproduction occurs by external fertilization when adults – which are usually gonochoric (separate sexes), though some taxa are hermaphroditic – spawn gametes into the water. (Ruppert, Fox, & Barnes 2004)
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Anthozoa
- Exclusively marine
- No medusa stage
- Includes sea anemones, corals, sea fans, sea pens, sea pansies
Scyphozoa
- Exclusively marine
- Lifecycle includes conspicuous medusa phase (most of the “jellyfish”)
- Includes box jellies, stalked jellies, flag-mouth jellies, root-mouth jellies
Hydrozoa
- Marine species as well as freshwater species
- Most species are colonial and lifecyles may include polyp, medusae, or both.
- Colonial species include hydroids, Portuguese man-of-war, fire and rose corals. Solitary species include a few jellies and freshwater Hydra.
(Ruppert, Fox, & Barnes 2004)
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| Rights holder/Author | Soulanille, Elaine, Soulanille, Elaine, EOL Rapid Response Team |
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Barcode of Life Data Systems (BOLD) Stats
Specimen Records:14040
Specimens with Sequences:8302
Specimens with Barcodes:5541
Species:1702
Species With Barcodes:982
Public Records:5656
Public Species:689
Public BINs:705
The larval stage of cnidarians can cause a condition known as seabather's eruption. This should not be confused with cercarial dermatitis, which is caused by certain schistosomatid trematode flatworms (e.g., Austrobilharzia variglandis) that normally use birds and mammals other than humans as their definitive hosts. The areas of skin affected by seabather's eruption is generally under the garments worn by bathers and swimmers where the organisms are trapped after the person leaves the water. In contrast, cercarial dermatitis occurs on the exposed skin outside of close-fitting garments.
(Centers for Disease Control Parasites and Health website)
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| Rights holder/Author | Shapiro, Leo, Soulanille, Elaine, EOL Rapid Response Team |
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Cnidarians are a diverse group of aquatic animals. More than 9,000 species are part of the Phylum Cnidaria, and all species are aquatic. Cnidarians are widespread in marine habitats and less common in fresh water.
This interesting group of invertebrates includes many charismatic organisms such as hydras, sea fans, jellyfishes, sea anemones, corals, and the Portuguese man-of-war. Cnidarians all have some type of specialized stinging cell organelle.
Cnidarians' bodies typically take one of two forms: the polyp or the medusa. While the polyp form is adapted for a sedentary or sessile lifestyle, the medusa form is adapted for floating or free-swimming. Sea anemones and corals (class Anthoza) are all polyps. True jellyfishes (class Scyphozoa) are all medusae, though some have a polyp larval stage. Notably, some hydroids (class Hydrozoa) alternate between polyp and medusa forms throughout their lives.
National Biological Information Infrastructure (NBII) at http://www.nbii.gov
- National Biological Information Infrastructure (NBII) at http://www.nbii.gov
Worldwide.
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Aquatic: mostly marine, though there are some freshwater species. Cnidarians include benthic, pelagic, and epibiont taxa.
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Most Cnidarians are either active or passive predators, capturing other animals with their nematocyst-lined tentacles. Many cnidaria living in well-lit habitats get much or most of their food from the mutalistic zooxanthellae or zoochlorellae within their gastrodermal cells.
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| Rights holder/Author | Soulanille, Elaine, Soulanille, Elaine, EOL Rapid Response Team |
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