Amoeba – Microworld

Amoeba proteus

Genus Amoeba Bory de St. Vincent, 1822

Diagnosis: Locomotive cells commonly polypodial, with several tubular pseudopodia bearing hemispherical tips and usually hyaline caps. One pseudopodium is dominant at a given time, often showing ectoplasmic ridges. In rapid locomotion the cell becomes monopodial. Nucleus single, granular in most described species. Resting cells irregularly rounded; floating form with long radiating pseudopodia. Cytoplasm often containing truncated bipyramidal crystals. Posterior uroid morulate.

Ecology: Freshwater; occurring in all types of freshwater habitats.

Key to the species:

1	Nucleus large (mean 40 µm), discoid, often biconcave	A. proteus
–	Nucleus smaller, spherical, ovoid, or compressed	2
2	Nucleus compressed-spherical, ovoid, or lens-shaped (mean 29 µm); crystals mainly squared	A. borokensis
–	Nucleus spherical, often slightly compressed; numerous bipyramidal crystals	A. leningradensis

Amoeba proteus: A-B-C polypodial forms; D monopodium; C specimen with numerous crystals; E dividing stage (fission sphere); F bipiramidal crystal; G tile-shaped crystal; H four crystals in a row.