Amoeboidflagellated

Amoeboidflagellated describes protists that display two distinct locomotor forms during their life cycle: an amoeboid form that moves by pseudopodia and feeds by phagocytosis, and a flagellated form that swims using one or more flagella. This dimorphism, seen in some eukaryotes, is a functional adaptation allowing rapid exploration of environments and dispersal. The term is descriptive rather than a formal taxonomic grouping; organisms labeled as amoeboidflagellated may not belong to a single lineage.

Within the eukaryotes, notable examples are in the group Heterolobosea (Percolozoa). Naegleria species, such as Naegleria fowleri and Naegleria gruberi, can exist as a free-living amoeba and transiently develop into a flagellated cell when conditions are favorable or stressful. In the amoeboid stage, they crawl by pseudopodia and feed on bacteria; in the flagellated stage, they become mobile swimmers, allowing colonization of new niches. The flagellated phase is typically short-lived and may be followed by reversion to the amoeboid form.

Ecology and significance: Many amoeboidflagellated organisms inhabit soil, freshwater, and decaying organic matter. Some species are of medical relevance; for example, Naegleria fowleri can invade the human nervous system after entering the nasal passages, causing fatal meningitis. Studying these organisms helps illuminate eukaryotic cell plasticity, motility, and adaptation to fluctuating environments.