Definition of radiolarian in US English:



  • A single-celled aquatic animal that has a spherical amoeba-like body with a spiny skeleton of silica. Their skeletons can accumulate as a slimy deposit on the seabed.

    Three classes of the phylum Actinopoda, kingdom Protista (formerly subclass or order Radiolaria)

    • ‘However, because of the morphological differences between modern radiolarians and ancient ones, it is difficult to reconstruct precisely the ecology of ancient radiolarians.’
    • ‘Won regarded the hollow canal structure as one of the indicators of the close relationship of radiolarians and the Porifera.’
    • ‘It is also noteworthy that these radiolarians generally have quite fine frameworks and thin shell walls, resulting in semitransparent specimens.’
    • ‘Like other radiolarians, Acantharea have an elaborate mineralized skeleton.’
    • ‘Therefore, in terms of geological age determined by radiolarians and the ammonoid, this brachiopod fauna should be assigned to the latest Changhsingian.’


  • Relating to or formed from radiolarians.

    ‘radiolarian ooze’
    • ‘Twenty-two samples for radiolarian research were collected from the grayish black, thin-bedded limestone and siliceous limestone of the Baoqing Member and the Mcishan Member.’
    • ‘This contradiction cannot be resolved at present due to a lack of Cambrian radiolarian studies, which are needed to provide chronostratigraphic corroboration.’
    • ‘Well-preserved Late Cambrian radiolarian faunas were recovered from carbonate rocks of the Cow Head Group of the Great Northern Peninsula of the island of Newfoundland, Canada.’
    • ‘This indicates that there existed a short period of radiolarian development before the great extinction at the Permian-Triassic transition.’
    • ‘Calcareous oozes are common in the low and mid-latitudes while in other places, particularly the high latitudes, radiolarian oozes tend to dominate.’