CnidariansSandra Benito J.H., 9B
Facts
Name: Cnidarians Before: Coelenterata phylum, meaning "hollow guts."
Included certain ctenophores and sponges. From the Greek "cnidos," meaning "stinging nettle.“
Number of species currently existing: 10,105 species
Taxonomic Classification: Domain: Eukaryota
Kindom: VI. Animalia Phyla: B. Cnidaria
Class: Cubozoa (Box jellies) Swimming Class: Scyphozoa (Jellyfishes) Swimming Class: Anthozoa (Anemones and corals) Sessile Class: Hydrozoa (Hydra) Both
Characteristics
Found in marine environments.Two basic body types:
PolypsMedusae
TentaclesVenomous cell organelles (cnidea)Gastrovascular cavityThree-layered body; epidermis, mesoglea and gastrodermisRadially symmetricCarnivorousSolitary or colonialAsexual and/or sexual reproductionNervous systemNo cardiovascular system
History
Fossil history:• Vendian/ Ediacaran period
• 650 to 540 million years
ago
• Soft-bodied organisms
•Cambrian period - coral fossils
•Early Ordovician - more
developed corals
Generalized Life CycleAnd Life Expectancy
Life span is undetermined.Life cycles vary by class and species
Some skip stages (e.g. Hydra)Alternation of generations (e.g. Obelia)
Asexual reproduction medusae grows on external tissueMatured medusae swim awaySexual cells releasedEggs are fertilizedZygote/planula settles and develops into a polyop
Digestive System
Absorb dissolved organic chemicals
Filter food particles
Nutrients from endosymbiotic algae
Predate
Crustaceans and plankton
Medusae forms sink on top of the prey
Gastrodem layer releases enzymes that kill
the prey
Cells absorb the nutrients
Nutrients spread by diffusion or mobile
cells
Indigestible remnants are ejected
Respiratory andCirculatory System
No circulatory systemNo respiratory organs
Absorb/expel O and CO2 into water
Water in digestive cavity is expelled
Sensory System
Simple sensory systemNet of nerves made of
sensitive neuronsSensitive neurons are
connected by chemical synapse
Neuron sends neurotransmitter (chemical) to cell group
BibliographyNew Oxford American Dictionaryhttp://en.wikipedia.org/wiki/Cnidariahttp://waynesword.palomar.edu/trnov01.htm#animalshttp://www.buzzle.com/articles/jellyfish-facts-for-kids.htmlhttp://animals.about.com/od/cnidarians/p/cnidaria.htmhttp://nationalzoo.si.edu/Animals/Invertebrates/Facts/cnidarians/default.cfmhttp://www.oceaninn.com/the-nature-preserve/cnidarians/http://mapress.com/zootaxa/2011/f/zt03148p012.pdfhttp://animals.about.com/od/cnidarians/ss/cnidarians.htmhttp://www.ucmp.berkeley.edu/cnidaria/cnidariafr.htmlhttp://www.angelfire.com/moon2/asciencems/http://zoology.muohio.edu/crist/Zoo312/Cnidaria.htmlhttp://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20102/bio
%20102%20lectures/nervous%20system/nervous1.htm
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