Cnidaria

Cnidaria

Languages: English

Ecology

Habitat

Aquatic: mostly marine, though there are some freshwater species.  Cnidarians include benthic, pelagic, and epibiont taxa.

Author(s): Soulanille, Elaine
Rights holder(s): Soulanille, Elaine

Distribution

Worldwide.

Author(s): Soulanille, Elaine
Rights holder(s): Soulanille, Elaine

Trophic Strategy

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.

Author(s): Soulanille, Elaine
Rights holder(s): Soulanille, Elaine

Predators

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.

Author(s): Soulanille, Elaine
Rights holder(s): Soulanille, Elaine

Reproduction

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)

Author(s): Soulanille, Elaine
Rights holder(s): Soulanille, Elaine

Associations

The gastrodermal cells of many cnidarians contain microscopic mutualistic algae, usually “zooxanthellae” (gold-brown) but in some Hydra and anemones the algae are green “zoochlorellae.”  The cnidarian host provides habitat, protection, CO2, and nutrients to the algae.  Photosynthate (sugars produced by photosynthesis) from the algae can supply as much as 90% of the cnidarian’s nutrition.  (Ruppert, Fox, & Barnes 2004)

Author(s): Soulanille, Elaine
Rights holder(s): Soulanille, Elaine

Evolution and Systematics

Systematics and Taxonomy

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)

Author(s): Soulanille, Elaine
Rights holder(s): Soulanille, Elaine

Relevance

Risk Statement

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)

Author(s): Shapiro, Leo
Rights holder(s): Shapiro, Leo

References

Andersen, V., & Sardou J. (1994).  PYROSOMA-ATLANTICUM (TUNICATA, THALIACEA) - DIEL MIGRATION AND VERTICAL-DISTRIBUTION AS A FUNCTION OF COLONY SIZE. JOURNAL OF PLANKTON RESEARCH. 16, 337-349.
Bridge, D., Cunningham C. W., Schierwater B., DeSalle R., & Buss L. W. (1992).  Class-level relationships in the phylum Cnidaria: evidence from mitochondrial genome structure. Proceedings of the National Academy of Sciences of the United States of America. 89, 8750-8753. Abstract
Butler, A. J., Rees T., Beesley P., & Bax N. J. (2010).  Marine Biodiversity in the Australian Region. PLoS ONE. 5(8), e11831.
Byrum, C. A., & Martindale M. Q. (2004).  Gastrulation in the Cnidaria and Ctenophora. Gastrulation: from Cells to Embryos (C. D. Stern, editor). 33-50. New York: Cold Spring Harbor Press.
Coll, M., Piroddi C., Steenbeek J., Kaschner K., Ben Rais Lasram F., Aguzzi J., et al. (2010).  The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats. PLoS ONE. 5(8), e11842.
Collins, A. G. (2002).  Phylogeny of Medusozoa and the evolution of cnidarian life cycles. Journal of Evolutionary Biology. 15(3), 418 - 432. Abstract
Costello, M J., Coll M., Danovaro R., Halpin P., Ojaveer H., & Miloslavich P. (2010).  A Census of Marine Biodiversity Knowledge, Resources, and Future Challenges. PLoS ONE. 5(8), e12110.
Cowles, D., Dyer A., & McFadden M. (2002).  Key to Invertebrates Found At or Near The Rosario Beach Marine Laboratory. 2011, Abstract
Danovaro, R., Company J B., Corinaldesi C., D'Onghia G., Galil B., Gambi C., et al. (2010).  Deep-Sea Biodiversity in the Mediterranean Sea: The Known, the Unknown, and the Unknowable. PLoS ONE. 5(8), e11832.
Fautin, D., Dalton P., Incze L. S., Leong J-A. C., Pautzke C., Rosenberg A., et al. (2010).  An Overview of Marine Biodiversity in United States Waters. PLoS ONE. 5(8), e11914.
Fujikura, K., Lindsay D., Kitazato H., Nishida S., & Shirayama Y. (2010).  Marine Biodiversity in Japanese Waters. PLoS ONE. 5(8), e11836.
Gordon, D. P., Beaumont J., MacDiarmid A., Robertson D. A., & Ahyong S. T. (2010).  Marine Biodiversity of Aotearoa New Zealand. PLoS ONE. 5(8), e10905.
Griffiths, C. L., Robinson T. B., Lange L., & Mead A. (2010).  Marine Biodiversity in South Africa: An Evaluation of Current States of Knowledge. PLoS ONE. 5(8), e12008.
Griffiths, H. J. (2010).  Antarctic Marine Biodiversity – What Do We Know About the Distribution of Life in the Southern Ocean?. (Unsworth R., Ed.).PLoS ONE. 5(8), e11683.
Grimmelikhuijzen, C. J., & Westfall J. A. (1995).  The nervous systems of cnidarians.. EXS. 72, 7-24. Abstract
Lebrato, M., & Jones D. O. B. (2009).  Mass deposition event of Pyrosoma atlanticum carcasses off Ivory Coast (West Africa). LIMNOLOGY AND OCEANOGRAPHY. 54, 1197-1209.
Metaxas, A., & Kelly N. E. (2010).  Do Larval Supply and Recruitment Vary among Chemosynthetic Environments of the Deep Sea?. (Thrush S., Ed.).PLoS ONE. 5(7), e11646.
MILLER, D., BALL E., & TECHNAU U. (2005).  Cnidarians and ancestral genetic complexity in the animal kingdom. Trends in Genetics. 21(10), 536 - 539. Abstract
Miloslavich, P., Díaz J M., Klein E., Alvarado J J., Díaz C., Gobin J., et al. (2010).  Marine Biodiversity in the Caribbean: Regional Estimates and Distribution Patterns. PLoS ONE. 5(8), e11916.
Monterey_Bay_Aquarium (2008).  Spotted Jelly, Coastal Waters, Invertebrates, Mastigias papua. Monterey: Monterey Bay Aquarium.
Muscatine, L. (1990).  The role of symbiotic algae in carbon and energy flux in reef corals. Coral Reefs (edited by Z Dubinsky). 25, 75-87. Amsterdam: Elsevier.
P?ppe, J., Sutcliffe P., Hooper J. N. A., W?rheide G., & Erpenbeck D. (2010).  CO I Barcoding Reveals New Clades and Radiation Patterns of Indo-Pacific Sponges of the Family Irciniidae (Demospongiae: Dictyoceratida). PLoS ONE. 5(4), e9950.
Rodríguez, E., & Daly M. (2010).  Phylogenetic Relationships among Deep-Sea and Chemosynthetic Sea Anemones: Actinoscyphiidae and Actinostolidae (Actiniaria: Mesomyaria). (Goldstien S., Ed.).PLoS ONE. 5(6), e10958.
Ruppert, E. E., Fox R. S., & Barnes R. D. (2004).  Cnidaria. Invertebrate Zoology: a Functional Evolutionary Approach. 111-180. Belmont, CA: Thomson: Brooks/Cole.
Warren, E. (1907).  On Parawrightia robusta gen. et sp. nov., a Hydroid from the Natal Coast; and also an Account of a Supposed Schizophyte occurring in the Gonophores. Annals of the Natal Government Museum. 1, 187-20.