Entamoeba histolytica: example of amoeboid protozoan

What they are - biological definition

Also known as Sarcodines, the Amoeboids are protozoa, that is, they belong to the Protist Kingdom.

Key Features of Amoeboids:

- Locomotion occurs through pseudopods (from Greek pseudo which means false and pruning which corresponds to walking). This type of locomotion is known as amoeboid movement.

- Capture food using pseudopods through the process of phagocytosis.

- They feed on algae, protozoa, bacteria and dead protoplasm.

- They have the ability to modify body shape, so they have no defined shape.

- Some species live in rivers and oceans, while others are parasites of living beings.

- They have a simple structure, consisting of: nucleus, contractile vacuole, food vacuole, endoplasma, ectoplasm and pseudopods.

- Body composed of hypertonic cells, causing water to enter the amoebas through the osmosis process. Excess water is eliminated by the contractile vacuole.

- Reproduction of most species of amoeboid protozoa occurs through binary division. In this system, an amoeba splits in half, giving rise to two others.

- Amoeboid protozoa are very small (microscopic). Most of them measure between 0.2 and 0.5 millimeters in diameter.

Examples of amoeboid protozoa:

- Amoeba proteus - freshwater protozoan

- Arcella vulgaris - Freshwater amoeba.

- Filamoeba sp.

- Hartmanella - free-living amoeboid protozoan (present in freshwater).

- Acanthamoeba - free-living amoeba (present in freshwater).

- Platyamoeba

Major diseases caused in humans:

- Amoebiasis - caused by protozoan Entamoeba histolytica that causes diarrhea.

- Primary Amoebic Meningoencephalitis - caused by amoeba Naegleria fowleri.

Biological curiosity:

- The amoeboid movement seen in these protozoa is similar to what happens with white blood cells (leukocytes) in humans.