Paramecium in the context of "Ciliate"

The green algae (sg.: green alga) are a group of chlorophyll-containing autotrophic algae consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophyta) have emerged deep within the charophytes as a sister of the Zygnematophyceae. Since the realization that the Embryophyta emerged within the green algae, some authors are starting to include them. The completed clade that includes both green algae and embryophytes is monophyletic and is referred to as the clade Viridiplantae and as the kingdom Plantae. The green algae include unicellular and colonial flagellates, most with two flagella per cell, as well as various colonial, coccoid (spherical), and filamentous forms, and macroscopic, multicellular seaweeds. There are about 22,000 species of green algae, many of which live most of their lives as single cells, while other species form coenobia (colonies), long filaments, or highly differentiated macroscopic seaweeds.

A few other organisms rely on green algae to conduct photosynthesis for them. The chloroplasts in dinoflagellates of the genus Lepidodinium, euglenids and chlorarachniophytes were acquired from ingested endosymbiont green algae, and in the latter retain a nucleomorph (vestigial nucleus). Green algae are also found symbiotically in the ciliate Paramecium, and in Hydra viridissima and in flatworms. Some species of green algae, particularly of genera Trebouxia of the class Trebouxiophyceae and Trentepohlia (class Ulvophyceae), can be found in symbiotic associations with fungi to form lichens. In general, the fungal species that partner in lichens cannot live on their own, while the algal species is often found living in nature without the fungus. Trentepohlia is a filamentous green alga that can live independently on humid soil, rocks or tree bark or form the photosymbiont in lichens of the family Graphidaceae. Also the macroalga Prasiola calophylla (Trebouxiophyceae) is terrestrial, andPrasiola crispa, which live in the supralittoral zone, is terrestrial and can in the Antarctic form large carpets on humid soil, especially near bird colonies.

Chromista is a proposed but controversial biological kingdom, refined from the Chromalveolata, consisting of single-celled and multicellular eukaryotic species that share similar features in their photosynthetic organelles (plastids). It includes all eukaryotes whose plastids contain chlorophyll c and are surrounded by four membranes. If the ancestor already possessed chloroplasts derived by endosymbiosis from red algae, all non-photosynthetic Chromista have secondarily lost the ability to photosynthesise. Its members might have arisen independently as separate evolutionary groups from the last eukaryotic common ancestor.

Chromista as a taxon was created by the British biologist Thomas Cavalier-Smith in 1981 to distinguish the stramenopiles, haptophytes, and cryptophytes. According to Cavalier-Smith, the kingdom originally consisted mostly of photosynthetic eukaryotes (algae), but he later brought many heterotrophs (protozoa) into the proposed group. As of 2022, the kingdom was nearly as diverse as the kingdoms Plantae and Animalia, consisting of nine phyla. Notable members include marine algae, potato blight, dinoflagellates, Paramecium, the brain parasite Toxoplasma, and the malarial parasite Plasmodium.

Myzocytosis (from Greek: myzein, (μυζεῖν) meaning "to suck" and kytos (κύτος) meaning "container", hence referring to "cell") is a method of feeding found in some heterotrophic organisms. It is also called "cellular vampirism" as the predatory cell pierces the cell wall and/or cell membrane of the prey cell with a feeding tube, the conoid, sucks out the cellular content and digests it.

Myzocytosis is found in Myzozoa and also in some species of Ciliophora (both comprise the alveolates). A classic example of myzocytosis is the feeding method of the infamous predatory ciliate, Didinium, where it is often depicted devouring a hapless Paramecium. The suctorian ciliates were originally thought to have fed exclusively through myzocytosis, sucking out the cytoplasm of prey via superficially drinking straw-like pseudopodia. It is now understood that suctorians do not feed through myzocytosis, but actually, instead, manipulate and envenomate captured prey with their tentacle-like pseudopodia.