"Flagellata" from Ernst Haeckel's Artforms of Nature, 1904

Flagellates are cells with one or more whip-like organelles called flagella. Some cells in animals may be flagellate, for instance the spermatozoa of most phyla. Flowering plants and fungi do not produce flagellate cells, but the closely related green algae and chytrids do. Many protists take the form of single-celled flagellates. They are found in most lines of eukaryotes, and it is likely that all surviving eukaryotes developed from them.

Green alga (Chlamydomonas)

Parasitic excavate (Giardia lamblia)