ciliato

Ciliato, in biology, refers to ciliates, a diverse group of single-celled eukaryotes in the phylum Ciliophora. They are characterized by numerous cilia covering the cell surface, used for locomotion and feeding. Most ciliates possess two kinds of nuclei: a macronucleus that governs everyday metabolic functions and a micronucleus involved in genetic exchange during sexual processes. The cytoplasm often includes a specialized oral apparatus (cytostome) for feeding and a posterior cytoproct for waste excretion. Many species have a contractile vacuole for osmoregulation and a pellicle reinforced by alveolar sacs that helps maintain cell shape.

Ciliates reproduce asexually by binary fission, and many species also undergo conjugation, a sexual process in which micronuclei are exchanged to increase genetic diversity. Some can form dormant cysts under adverse conditions.

Ecologically, ciliates inhabit freshwater, marine environments and soils, existing as free-living organisms, symbionts, or occasionally parasites. Notable genera include Paramecium and Tetrahymena, which are common model organisms in laboratory studies; Vorticella and Stentor, which are often stalked; and Balantidium coli, a human parasite. They feed primarily by sweeping bacteria and other small particles into their oral region, contributing to nutrient cycling in microbial communities.

Taxonomically, ciliates belong to the phylum Ciliophora within the supergroup Alveolata. They are distinguished from other protozoa by their coordinated ciliary movement, dual nuclear apparatus, and complex oral structures.

Etymology: the name derives from Latin cilium, meaning "eyelash," reflecting their hairlike cilia. The term ciliato is the Italian adjective used to describe ciliates or ciliated organisms.