Infusoria

Infusoria is a collective term for minute aquatic creatures like ciliates, euglena, paramecia, protozoa and unicellular algae that exist in freshwater ponds. However, in formal classification a microorganism called infusoria belongs to Kingdom Protista.

Aquarium use
Infusoria creatures are used by owners of aquariums to feed fish fry; gourami fry and tadpoles are just two examples which will require this food to survive the first few days. However there is usually not enough infusoria in the average aquarium tank to feed the newly hatched animals.

Myonemes
In Infusoria and some Flagellates, the differentiated threads of ectosarc, which are contractile and doubly refractive, perform the function of muscular fibres in the Metazoa.