Actinophrys sol is a fresh-water species of heliozoa frequently referred to as the sun animalcule. The name spawns from the numerous radiating pseudopodia that surround the spherical organism, which give it a sun-like appearance under the microscope.
The pseudopodia of Actinophrys species and other heliozoans are generally used to capture prey. However, the cytoplasmic extensions can also be utilized to some extent for locomotion of the organisms. Heliozoans contain several large vacuoles and feed by engulfing their prey through a process known as phagocytosis. The tiny creatures consume almost anything in their path, primarily protozoa and algae, paying little heed to the size of their prey.
Found predominantly in freshwater, Actinophyrs sol is common in lakes, ponds, and pools. The species usually reproduces via binary fission, but can also propagate through autogamy, which results in zygotes that are able to defer development until conditions are suitable. A similar species, Acanthocystis turfacea, colored by the green algae with which it lives in symbiosis, is frequently called the green sun animalcule.