Shield euglenoid
Phacus
Phacus is a genus of euglenoids characterized by a flat, leaf-like, and rigid body structure due to a firm pellicle. The cells possess a prominent red eyespot (stigma) and a single long flagellum for locomotion. They are found globally in stagnant, mostly nutrient-rich freshwater bodies and actively perform photosynthesis.
Details
Oxygen production
Produces oxygen as a byproduct of photosynthesis during the light phase.
Habitat function
Serves as a food source for microorganisms in the pelagic zone.
Nutrient uptake
Efficient uptake of nitrogen and phosphate compounds.
Food source for
Zooplankton, especially rotifers.
Human use
Used in environmental analysis to determine water quality (saprobic system).
Ecology
Ecological role
Primary producer in aquatic systems; converts inorganic CO2 and sunlight into biomass.
Natural predators
Filter-feeding zooplankton such as rotifers (Rotatoria) and small crustaceans (Cladocera).
Competitor species
Other phytoplankton genera such as Euglena or green algae.
Ecosystem service
Oxygen production through photosynthesis and base of the food chain.
Threats
Extreme chemical toxicity or herbicide contamination in water bodies.
Scientific profile
Profile
Distinguishing features
Rigid cell shape (unlike Euglena), flattened body structure, prominent red eyespot (stigma) at the anterior end, large paramylon granules, and usually spiral or longitudinal pellicular striations.
Reproduction
Asexual reproduction via longitudinal binary fission.
Protection & threats
Status not on standard scale
Main threats
Destruction of small water bodies through infilling or drainage; extreme acidification due to atmospheric deposition.
Conservation measures
Preservation and creation of ponds and pools; management of nutrient input from agriculture to prevent hypertrophy.