Circumscription: A group of marine radiolaria (protists with axopodia, skeletons, and no flagella in the trophic state). Most have a skeleton of amorphous silica with associated organic matter, cytoplasm separated into an inner area by a thick capsule, and an inner layer that is further divided by a cape of vesicles-the cape having three openings: an apical astropyle that seems to be associated with the formation of feeding pseudopodia and two parapyles from which axonemal microtubules arise. Contain aggregates of waste material: the phaeodium. Life cycle may be complex, and flagellated distributive stages are produced. Ultrastructural identity: Little studied, mitochondria probably tubulocristate. Synapomorphy: Radiolaria with central capsule with three openings: an apical astropyle and two parapyles.

Radiolaria is prey of:
Acartia
Oithona-Oncaea type
Calanus
Centropages
Amphipoda

Based on studies in:
Pacific (Tropical)

This list may not be complete but is based on published studies.

Radiolaria preys on:
detritus
phytoplankton
bacteria

Based on studies in:
Pacific (Tropical)

This list may not be complete but is based on published studies.