Actinophryid

The actinophryids are small, familiar group of heliozoan protists. They are the most common heliozoa in fresh water, and are especially frequent in lakes and rivers, but a few are found in marine and soil habitats as well. Each actinophryid are unicellular and roughly spherical in shape, without any shell or test, and with many pseudopodia supported by axopods radiating outward from the cell body, which adhere to passing prey and allows it to roll or float about. The outer portion of the cell, or ectoplasm, is distinct and is filled with many tiny vacuoles, which assist in flotation. This is very similar to the process of osmosis. The movement of water from inside the cell to the outside is not because of water concentration in this case. It is the cell pushing the excess water out. A few contractile vacuoles around the periphery of the cell expel excess water, and are visible as clear bulges when full.