Population

Description:

Actinosphaerium (act-in-o-sphere-ee-um) (=Echinosphaerium), one of the largest freshwater heliozoa, may measure up to 500 microns, often with outer layer being very vacuolated. This group photograph shows some of the variation in size. Multiple nuclei and nucleating sites for the arms line at the interface between the inner and outer regions of cytoplasm. Yellowy zones in the centre is some food being digested - these heliozoa can consume small metazoa. Dark ground illumination.