- 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 of radiolarian
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for radiolarian
Most of these Radiolarian marls appear to date from the middle Tertiary (Miocene) period, and to be deep-sea formations.
We unite here all these skeletonless Radiolarian colonies into one single genus Collozoum, constituted in my Monograph (p. 522).
In several cases the character of the Radiolarian fauna at different depths presented characteristic differences.
A larger number of new forms has been found in the Radiolarian ooze collected by the Challenger, and others fossil in Barbados.
This remarkable species is the oldest known skeleton of a Radiolarian, a figure of it being given in 1838, loc.
- any of various marine protozoans constituting the order Radiolaria, typically having a siliceous shell and stiff radiating cytoplasmic projections: phylum Actinopoda (actinopods)
C19: from New Latin Radiolaria, from Late Latin radiolus little sunbeam, from Latin radius ray, radius
Word Origin and History for radiolarian
1862, from Radiolaria, Modern Latin classification name, from Latin radiolus, diminutive of radius (q.v.).
Online Etymology Dictionary, © 2010 Douglas Harper
- 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.
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