Amoebas

Amoebas are a diverse group of unicellular protists that move and feed by forming temporary projections called pseudopodia, or “false feet.” They are not a single clade but an informal name for various amoeboid organisms. Most belong to the supergroup Amoebozoa, though amoeboid forms occur in other lineages as well. A typical amoeba has a flexible cell membrane, and its cytoplasm is often described as an outer clear ectoplasm and an inner granular endoplasm; many species lack a rigid cell wall, allowing substantial shape change.

Amoebas inhabit a range of environments, including freshwater, soil, sediments, and marine habitats. They feed by phagocytosis, engulfing bacteria, algae, and other small particles. Their distinctive shape-shifting ability helps them capture prey and move through their surroundings. Many survive adverse conditions by forming cysts, dormant protective structures that can resist desiccation or other stresses until conditions improve.

Reproduction in amoebas is typically asexual, most commonly by binary fission, in which the cell splits into two identical daughter cells. Some species can undergo other modes of division, such as multiple fission, and certain lineages form cysts or engage in cryptic sexual processes, though sexual reproduction is not common in many amoeboid groups.

Several amoebas are of medical or veterinary significance. Entamoeba histolytica can cause amoebic dysentery in humans, while Naegleria fowleri and some Acanthamoeba species can cause severe, sometimes fatal infections under certain conditions. Beyond pathogens, amoebas play ecological roles in nutrient recycling by grazing on microbes and shaping microbial communities. In research, amoebas have contributed to understanding fundamental cellular processes such as locomotion, phagocytosis, and differentiation.