as an adjective, "possessing a ventral feeding groove that collects suspended particles driven into it by the beating of a posterior flagellum." Simpson et al. (2002: 239). The "excavate hypothesis" is the hypothesis that the excavate taxa are monophyletic, vis. the taxon Excavata.
The excavates are a major line of protists, often known as Excavata. The phylogenetic category Excavata includes a variety of free-living and symbiotic forms, as well as microbes varying as to whether they contain mitochondria (that is, amitochondriate versus discicristate). Excavates are usually characterized by having two, four, or more flagella with distinct ultrastructure anterior to a ventral feeding groove supported by microtubules.