Ciliates
Ciliophora
Ciliates are highly complex, unicellular organisms found in almost all environments with water. They are characterized by the presence of cilia, which are used for locomotion and feeding. Another defining feature is nuclear dimorphism, possessing both a large macronucleus and a small micronucleus. They play a crucial role in the microbial loop of aquatic ecosystems.
Details
Identification
Presence of cilia, oral groove (cytostome), contractile vacuoles, and two distinct types of nuclei (macronucleus and micronucleus).
Social behavior
Mostly solitary, some species form colonies or live in symbiosis/parasitism.
Diet
Diet primarily consists of bacteria, algae, flagellates, and other protists, which are swept into the oral region by ciliary movement.
Hunting strategy
Filter feeders or active predators that paralyze prey using specialized organelles (extrusomes).
Overwintering
Formation of resting stages (cysts) under unfavorable environmental conditions.
Ecology
Ecological role
Key components of the microbial loop; they transfer bacterial biomass into the classical food web.
Natural predators
Rotifers, small crustaceans (e.g., copepods), predatory protists, and larval fish.
Competitor species
Other heterotrophic protists such as amoebae or flagellates.
Ecosystem service
Water purification through bacterial consumption and nutrient recycling in aquatic systems.
Threats
Extreme chemical pollution, ocean acidification, and habitat loss due to the drying out of small water bodies.
Scientific profile
Profile
Habitat
Ubiquitously distributed in freshwater, brackish water, marine environments, and moist soils; also as commensals or parasites in metazoans.
Reproduction
Asexual by transverse binary fission; genetic recombination occurs via conjugation (exchange of micronuclei).
Ecological role
Key role in the 'microbial loop'; transfer of bacterial biomass to higher trophic levels (zooplankton).