Necked testate amoeba
Difflugia oblonga
Difflugia oblonga is a unicellular organism belonging to the testate amoebae, characterized by a distinctive pear-shaped or bottle-shaped shell. This shell (test) is constructed from gathered sand grains or diatom frustules cemented together with an organic secretion. The amoeba primarily inhabits the sediments of freshwater ecosystems and moves using finger-like pseudopodia (lobopodia). It plays a significant role in the microbial food web as a consumer of bacteria and algae.
Details
Identification
Pear-shaped shell with a distinct neck, rough surface due to attached sand grains, a single opening (pseudostome) at the narrow end.
Social behavior
Solitary living unicellular organism.
Diet
Feeds as a generalist on bacteria, unicellular algae (especially diatoms), and organic detritus.
Hunting strategy
Phagocytosis using pseudopodia to engulf food particles.
Overwintering
Formation of cysts (resting stages) within the sediment.
Ecology
Ecological role
Important component of the benthic micro-community; regulates bacterial populations and serves as food for larger invertebrates.
Natural predators
Rotifers, small crustaceans, and predatory protozoa.
Competitor species
Other testate amoebae species such as Arcella or Centropyxis.
Ecosystem service
Contribution to nutrient recycling in aquatic sediments.
Threats
Sediment pollution by heavy metals and pesticides, excessive eutrophication.
Scientific profile
Profile
Habitat
Widely distributed in freshwater habitats; benthic in sediments of lakes and ponds, in peat bogs (Sphagnum), and on aquatic plants. Prefers stagnant or slow-flowing waters.
Reproduction
Asexual reproduction by binary fission. Prior to cell division, the amoeba collects mineral particles used to construct the new shell for the daughter cell during division.
Ecological role
Important component of the microbial food web; regulates microbial populations and serves as a link for energy transfer to higher trophic levels (meiofauna).