Amoeboidea

Amoeboidea is a major clade of amoeboid protists, commonly referred to as amoebas. These eukaryotic organisms are characterized by their ability to move and feed using pseudopodia, which are temporary cellular extensions. Amoeboidea are found in a wide range of environments, including freshwater, marine habitats, soil, and even as parasites or commensals within other organisms. Their morphology is typically irregular and can change dynamically as they extend and retract their pseudopodia.

The life cycle of amoeboideans often involves a single-celled stage, though some may form multicellular structures like plasmodia. Reproduction is primarily asexual, usually through binary fission. Some species can form cysts for survival in unfavorable conditions. Amoeboidea are ecologically significant as decomposers and as a food source for other microorganisms. They play roles in nutrient cycling within their respective ecosystems.

Classification within Amoeboidea has historically been complex, with many groups being defined by morphological characteristics. Modern molecular phylogenetic studies have significantly refined our understanding of their evolutionary relationships. Key subgroups include Amoebida, Mycetozoa (which includes slime molds), and Coproamoebida. Some amoeboideans, like the genus Entamoeba, are known human pathogens, causing diseases such as amoebic dysentery. However, the vast majority of amoeboideans are free-living and harmless.