sun animalcule

heliozoan

Also known as: Actinophrys sol

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Last updated

July 14, 2026

Quick Summary

Heliozoans are a type of protozoan, often called "sun animalcules" due to their spherical shape and radiating cytoplasmic extensions called pseudopodia (or axopodia). These organisms are typically found in freshwater environments and can float freely or be attached to surfaces.1

Key characteristics of heliozoans include:
* Appearance: Spherical with numerous radiating pseudopodia used for capturing food.1
* Habitat: Predominantly freshwater.1
* Structure: May be enclosed in a shell made of silica or organic material.1
* Diet: Ingest smaller organisms like protozoans and algae.1
* Reproduction: Primarily asexual, through binary fission or budding.1

A common example is Actinophrys sol, also known as the sun animalcule. Some species, like Acanthocystis turfacea, are green due to symbiotic algae.1

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heliozoan
…often referred to as the sun animalcule. Acanthocystis turfacea is a similar species commonly called the green sun animalcule because its body is coloured by harmless symbiotic green algae (zoochlorellae). Actinosphaerium species are multinucleate, often reaching a diameter of 1 mm (0.04 inch).
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…often referred to as the sun animalcule. Acanthocystis turfacea is a similar species commonly called the green sun animalcule because its body is coloured by harmless symbiotic green algae (zoochlorellae). Actinosphaerium species are multinucleate, often reaching a diameter of 1 mm (0.04 inch).
Read More