Small amoeba
Acanthamoeba spp.
The small amoeba is a single-celled microorganism that moves and feeds by extending pseudopodia. As a naked amoeba, it lacks a rigid cell wall, allowing for constant shape changes throughout its life cycle. It is globally distributed in moist soils, freshwater, and various aquatic biofilms. Playing a key role in the microbial loop, it regulates bacterial populations through the process of phagocytosis.
Details
Identification
Microscopic size, slow crawling movement, formation of pseudopodia, visible contractile vacuole under a microscope.
Social behavior
Solitary, but forms resting stages (cysts) during food shortages or desiccation.
Diet
Feeds primarily on bacteria, algae, and organic detritus through phagocytosis.
Hunting strategy
Surrounding food particles with pseudopodia to form food vacuoles.
Overwintering
Formation of resistant cysts to survive unfavorable environmental conditions.
Ecology
Ecological role
Important consumer in the microbial food web and promoter of nutrient recycling in soils and water bodies.
Natural predators
Larger protozoa (e.g., ciliates), rotifers, and small nematodes.
Competitor species
Other bacterivorous protists such as ciliates and flagellates.
Ecosystem service
Water purification through bacterial control and essential contribution to soil fertility.
Threats
Severe chemical contamination of water bodies and extreme desiccation of habitats.
Scientific profile
Profile
Habitat
Ubiquitous in soil, freshwater, brackish water, and marine habitats; frequently found in anthropogenic systems such as drinking water pipes, air conditioning units, and swimming pools.
Reproduction
Asexual reproduction via binary fission of the trophozoite; encystment into a resistant resting stage occurs under stress conditions.
Ecological role
Important predator in microbial food webs; regulates bacterial populations in soil and water, thereby promoting microbial diversity.