\pˌɒlɪzˈə͡ʊə], \pˌɒlɪzˈəʊə], \p_ˌɒ_l_ɪ_z_ˈəʊ_ə]\
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By Princeton University
By DataStellar Co., Ltd
A class of animals forming the lowest members of the Mollusca, and generally known by the popular names of "sea-mosses" and "sea-mats." They are invariably compound, forming associated growths or colonies produced by gemmation from a single primordial individual, and inhabit a polyzoarium, corresponding to the polypidom of the composite hydroids. The typical polypide of a polyzoon differs from the polypite of the Hydrozoa in having a distinct alimentary canal suspended freely in a body cavity, and in having the reproductive organs contained within the body. The body is inclosed in a doublewalled sac, the outer layer (ectocyst) of which is chitinous or calcareous, and the inner (endocyst) a delicate membranous layer. All the Polyzoa are hermaphrodite. Besides true sexual reproduction, and besides the power of producing colonies by continous budding, fresh individuals are in many cases produced by a process of discontinuous gemmation. The Polyzoa are chiefly marine, encrusting stones, old shells, and sea-weeds; but some are fresh-water.
By Daniel Lyons
By Nuttall, P.Austin.
Word of the day
- A genus of small tapeworms birds and mammals. A genus of Cestoda or tapeworms. A cestode worm order Cyclophyllideae, family Hymenolepinidae, genus Hymenolepis. includes several genera, such as H. Diminuta, occasionally infesting children, and Nana, or the dwarf tapeworm of children. Flavopuncta. See Taenia flavopuncta, under tenia.