Ameboid

Ameboid is an adjective used to describe cells, organisms, or movements that resemble an amoeba. As a noun, it may refer to an amoeboid cell or organism that uses amoeboid movement.

Ameboid movement is achieved by extending temporary cytoplasmic projections called pseudopodia. The cytoplasm is typically divided into an outer, more gel-like ectoplasm and an inner, more fluid endoplasm. Actin polymerization drives pseudopod formation and retraction, allowing the cell to crawl over surfaces in a flexible, plastic manner. Pseudopodia can be lobopodial (bulbous), lamellipodial (sheet-like), or filopodial (slender).

Ameboid organisms are widespread among eukaryotes. Free-living amoebae, such as many members of the Amoebozoa, move and feed by engulfing prey with pseudopods. In animals, several cell types migrate amoeboidly during immune responses, including macrophages and neutrophils, and ameboid movement plays a role in tissue remodeling. Ameboid locomotion is also seen in certain life stages of slime molds and other protists.

Ameboid motion is distinct from locomotion driven by flagella or cilia, relying on cytoskeletal remodeling and substrate adhesion. It can be highly flexible and adaptive but may be less efficient for long-distance travel than flagellated modes. In research, ameboid movement is studied to understand basic cell migration, immune cell behavior, and the evolution of eukaryotic cytoskeletal dynamics.

Etymology and usage: from Greek ameibe, change; ameboid is a common alternative spelling to amoeboid in modern texts.