Infusories, also known as infusoria or infusorial animalcules, refer to a large group of microscopic aquatic organisms belonging to the phylum Ciliophora. They are single-celled protozoans characterized by the presence of hair-like structures called cilia, which cover their body and aid in locomotion and feeding. Infusories are extremely diverse and can be found in various freshwater and marine environments, as well as in moist terrestrial habitats.
Infusories are often referred to as "infusorians" due to their common occurrence in infusions of plant or animal matter left in water, such as decaying organic material. These microorganisms play a crucial role in the ecosystem as they are significant in microbial food webs and contribute to nutrient recycling.
As heterotrophs, infusories feed on bacteria, algae, yeast, and other microorganisms, but some species are also known to be carnivorous, preying on smaller protozoans. They use their cilia to create water currents that bring food particles towards their mouth, where they engulf and digest them.
Infusories exhibit a wide range of sizes, shapes, and complexity. Some species are relatively simple, while others possess specialized structures for defense, mating, or capturing prey. These versatile organisms reproduce asexually through binary fission or multiple fission, producing daughter cells that are genetically identical to the parent cell.
Due to their abundance and ease of observation with the aid of a microscope, infusories have long been of interest to scientists and naturalists. They have contributed to our understanding of various biological processes, including cell structure and function, movement, and reproduction.
