Studies of living radiolarians in the field and in the laboratory reveal the extent of their trophic diversity. Solitary and colonial radiolarians feed opportunistically on a wide variety of prey organisms in nature, but respiration studies have shown that they can rely heavily on their symbiotic algae to provide the energy required for basal metabolism. Some radioisotopic evidence has implicated an intricate relationship between the host, its predatory success and the photosynthesis by its symbionts.

Field data on the abundance of subtropical radiolarians suggest that their populations respond to seasonal changes such as temperature. The existence of separate cohorts in a population suggests that several life cycles may occur in a single season lasting only a few months.

Such studies will amplify our understanding of the interactions of the radiolarians with the biological component of their environment based on their nutritional requirements and physiological limitations. This is an important first step towards elucidation of which factors affect the distribution of radiolarians.

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