An assemblage of eukaryotic protists characterized by one or more feeding grooves equipped with undulipodia (flagella) that propel food to the mouth. They include the diplomonads (e.g. Giardia, responsible for giardiasis in humans), other gut parasites or symbionts (retortamonads and oxymonads), trichomonads (such as the human vaginal parasite Trichomonas), and the jakobids (a class of zoomastigotes). Molecular systematics reveals that excavates could be a very early eukaryote lineage, a view supported by their simplified organelles and by the fact that the jakobids have mitochondrial genomes that are remarkably similar to those of bacteria, attesting to the ancient origin of mitochondria as intracellular symbiotic bacteria.
Subjects: Biological Sciences.