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Hydrozoa
Hydrozoa (hydroids; phylum Cnidaria) A class of multicellular, mainly marine animals in which the cells are derived from two layers, epidermis and gastrodermis (endodermis), separated by a gelatinous mesogloea. These enclose a continuous gastrovascular cavity (coelenteron), which communicates directly with the exterior by a single aperture (mouth) and is lined by a gastrodermis. The gastrodermis lacks nematocysts. Eggs and sperm are shed outside the animal and not into the gastrovascular cavity.
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Cite this article
MICHAEL ALLABY. "Hydrozoa." A Dictionary of Zoology. 1999. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "Hydrozoa." A Dictionary of Zoology. 1999. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O8-Hydrozoa.html MICHAEL ALLABY. "Hydrozoa." A Dictionary of Zoology. 1999. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-Hydrozoa.html |
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Hydrozoa
Hydrozoa (hydroids; phylum Cnidaria) Class of multicellular, mainly marine animals with cells arranged in two layers, the epidermis and the gastrodermis (endodermis), separated by a gelatinous mesogloea. These enclose a continuous digestive cavity (coelenteron), which communicates directly with the exterior by a single aperture (mouth) and is lined by a gastrodermis. The gastrodermis lacks nematocysts. Hydrozoa are Lower Cambrian to Recent. See also MILLEPORINA; and STYLASTERINA.
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Cite this article
AILSA ALLABY and MICHAEL ALLABY. "Hydrozoa." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "Hydrozoa." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O13-Hydrozoa.html AILSA ALLABY and MICHAEL ALLABY. "Hydrozoa." A Dictionary of Earth Sciences. 1999. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-Hydrozoa.html |
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hydrozoa
hydrozoa Class of animals without backbones, all living in water, belonging to the phylum Coelenterata. They vary in shape and size from the large Portuguese man-of-war to the simple hydra.
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"hydrozoa." World Encyclopedia. 2005. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "hydrozoa." World Encyclopedia. 2005. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O142-hydrozoa.html "hydrozoa." World Encyclopedia. 2005. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-hydrozoa.html |
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Hydrozoa
Hydrozoa See Cnidaria.
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Cite this article
"Hydrozoa." A Dictionary of Biology. 2004. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "Hydrozoa." A Dictionary of Biology. 2004. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O6-Hydrozoa.html "Hydrozoa." A Dictionary of Biology. 2004. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O6-Hydrozoa.html |
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