Spiny testate amoeba
Centropyxis aculeata
The spiny testate amoeba (Centropyxis aculeata) is a unicellular organism belonging to the group of testate amoebae. Its shell or test is composed of an organic matrix embedded with small sand grains or diatom fragments (xenosomes). A defining feature of this species is the presence of two to eight prominent spines located at the posterior margin of the test. It primarily inhabits the benthic sludge of stagnant waters, as well as moist mosses and peatlands.
Details
Identification
Cap-like, often flattened test; 2-8 eccentric spines at the posterior end; shell surface covered with foreign particles; finger-like pseudopodia (lobopodia).
Social behavior
Solitary living microorganism.
Diet
Feeds heterotrophically on bacteria, algae (especially diatoms), fungal spores, and organic detritus.
Hunting strategy
Phagocytosis by engulfing food particles with pseudopodia.
Overwintering
Formation of resting stages (cysts) during desiccation or cold periods.
Ecology
Ecological role
Important part of the microbial loop; decomposes organic matter and serves as a link to higher trophic levels.
Natural predators
Larger ciliates, rotifers, and small benthic crustaceans.
Competitor species
Other testate amoeba species such as Difflugia species.
Ecosystem service
Contribution to nutrient cycling and control of bacterial populations in aquatic sediments.
Threats
Loss of wetlands, extreme eutrophication, and toxic sediment contamination.
Scientific profile
Profile
Habitat
Cosmopolitan in freshwater habitats; prefers lake and pond sediments, stagnant waters, Sphagnum mosses, and moist soils.
Reproduction
Asexual reproduction by binary fission, involving the construction of a new daughter test.
Ecological role
Important consumer in the microbial loop; regulates bacterial populations and serves as a link to higher trophic levels.