Amoebozoa

Amoebozoa is a major taxonomic group containing about 2,400 described species of amoeboid protists, often possessing blunt, fingerlike, lobose pseudopods and tubular mitochondrial cristae. In most classification schemes, Amoebozoa is ranked as a phylum within either the kingdom Protista or the kingdom Protozoa. In the classification favored by the International Society of Protistologists, it is retained as an unranked "supergroup" within Eukaryota. Molecular genetic analysis supports Amoebozoa as a monophyletic clade.

Characteristics

Most amoebae are small (10–20 μm) and are not easily detected by the human eye; however, some species, such as the so-called "giant amoebae" Pelomyxa palustris and Chaos carolinense, can be large enough to see without aid.

Amoebozoa cells are often adhesive. The cell surface is rich in glycoproteins and extrusomes. When food is detected, the amoeba puts out pseudopods to surround and trap the food particle within a food vacuole. Enzymes from the lysosomes are then released into the vacuole to digest the particles.

Classification

Amoebozoa is a large and diverse group, but certain features are common to many of its members. The amoebozoan cell is typically divided into a granular central mass, called endoplasm, and a clear outer layer, called ectoplasm. During locomotion, the endoplasm flows forwards and the ectoplasm runs backwards along the outside of the cell. In motion, many amoebozoans have a clearly defined anterior and posterior and may assume a "monopodial" form, with the entire cell functioning as a single pseudopod. Large pseudopods may produce numerous clear subpseudopodia. A cell may also form multiple indeterminate pseudopodia, through which the entire contents of the cell flow in the direction of locomotion.

Pathogenic Amoebozoa

Some amoebae, such as those in the genus Entamoeba, can be pathogenic to humans, causing a disease called amoebiasis. Entamoeba histolytica is the cause of amoebic dysentery and liver abscesses, resulting in approximately 100,000 deaths worldwide each year.

See also

• Amoebiasis
• Entamoeba
• Protista
• Protozoa