The alveolates are a group of protists, considered a major clade and superphylum within Eukarya. They are currently grouped with the stramenopiles and Rhizaria among the protists with tubulocristate mitochondria into the SAR supergroup.
Alveolate
Transmission electron micrograph of a thin section of the surface of the ciliate Paramecium putrinum, showing the alveoli (red arrows) under the cell surface
Paramecium caudatum (Ciliophora)
Vorticella (Ciliophora) (left)
A protist or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural group, or clade, but are a polyphyletic grouping of several independent clades that evolved from the last eukaryotic common ancestor.
Protist
Phylogenomic tree of eukaryotes, as regarded in 2020. Supergroups are in color.
Goldfuss' system of life, introducing the Protozoa within animals.
John Hogg's illustration of the Four Kingdoms of Nature, showing "Regnum Primigenum" (Protoctista) as a greenish haze at the base of the Animals and Plants, 1860