Common Euglena
Euglena gracilis
Euglena gracilis is a spindle-shaped unicellular organism characteristic of nutrient-rich stagnant waters. It possesses chloroplasts for photosynthesis but can also feed heterotrophically on organic substances in the absence of light. A prominent feature is the red eyespot (stigma), which, together with the photoreceptor at the base of the flagellum, serves for light perception. It moves by swimming with a long flagellum but can also change its shape by contracting its flexible pellicle.
Details
Oxygen production
High during the light phase due to active photosynthesis.
Habitat function
Preferentially colonizes small, stagnant, eutrophic water bodies such as ponds, puddles, and liquid manure pits.
Nutrient uptake
Very efficient uptake of ammonium, nitrate, and phosphate.
Food source for
Serves as a base component of the food chain for various zooplankton.
Human use
Used as a model organism in research, biomonitoring, and extraction of paramylon for dietary supplements.
Ecology
Ecological role
Important primary producer and simultaneously a consumer of organic loads; serves as a link in the microbial loop.
Natural predators
Zooplankton such as rotifers, small crustaceans, and predatory protozoa.
Competitor species
Other phytoplankton such as green algae (e.g., Chlamydomonas) or cyanobacteria.
Ecosystem service
Oxygen production through photosynthesis and reduction of organic water pollution.
Threats
Excessive herbicide pollution in water bodies and complete desiccation of habitats.
Scientific profile
Profile
Distinguishing features
Possesses a prominent red eyespot (stigma) outside the chloroplasts near the flagellar base. Numerous discoid chloroplasts with pyrenoids. Storage product is paramylon (a β-1,3-glucan), occurring as granules in the cytoplasm.
Reproduction
Asexual reproduction by longitudinal binary fission. Sexuality has not been scientifically proven for this species.
Protection & threats
Status not on standard scale
Main threats
No known threats; the species is widespread and benefits from anthropogenic nutrient inputs.
Conservation measures
No specific conservation measures required; management usually focuses on reducing eutrophication in affected water bodies.