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radiolarian

[rey-dee-oh-lair-ee-uh n] /ˌreɪ di oʊˈlɛər i ən/
noun
1.
any minute, marine protozoan of the class Radiolaria, or, in some classification schemes, the superclass Actinopoda, having an amebalike body with radiating, filamentous pseudopodia and a usually elaborate outer skeleton.
Origin
1875-1880
1875-80; < Neo-Latin Radiolari(a) name of the group (Latin radiol(us) a small beam, equivalent to radi(us) radius + -olus -ole1 + -aria -aria) + -an
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples from the web for radiolarian
  • The buckyball shape at top is a dead radiolarian, a one-celled animal with a silica skeleton.
British Dictionary definitions for radiolarian

radiolarian

/ˌreɪdɪəʊˈlɛərɪən/
noun
1.
any of various marine protozoans constituting the order Radiolaria, typically having a siliceous shell and stiff radiating cytoplasmic projections: phylum Actinopoda (actinopods)
Word Origin
C19: from New Latin Radiolaria, from Late Latin radiolus little sunbeam, from Latin radius ray, radius
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Word Origin and History for radiolarian
n.

1862, from Radiolaria, Modern Latin classification name, from Latin radiolus, diminutive of radius (q.v.).

Online Etymology Dictionary, © 2010 Douglas Harper
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radiolarian in Science
radiolarian
  (rā'dē-ō-lâr'ē-ən)   
Any of various marine protozoans of the group Radiolaria, having rigid skeletons usually made of silica. The skeletons are usually spherically symmetrical and structurally complex, containing elaborate patterns of perforations (through which pseudopods extend) and often spicules. Skeletal remains of radiolarians sink to form ooze on the ocean floor, and prehistoric radiolarian ooze has fossilized to become chert and flint.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Article for radiolarian

any protozoan of the class Polycystinea (superclass Actinopoda), found in the upper layers of all oceans. Radiolarians, which are mostly spherically symmetrical, are known for their complex and beautifully sculptured, though minute, skeletons, referred to as tests. Usually composed of silica, the test is elaborately perforated in a variety of patterns, forming a series either of latticelike plates or of loose needle-shaped spicules. Pseudopodia extend through the perforated skeleton. A chitinous central capsule encloses the nuclei and divides the cytoplasm into two zones. The outer cytoplasm contains many vacuoles that control the organism's buoyancy.

Learn more about radiolarian with a free trial on Britannica.com
Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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