Spherical water flea
Chydorus sphaericus
Chydorus sphaericus is one of the most widespread and adaptable water flea species globally. It is characterized by its distinctive, nearly spherical body shape and small size. The species inhabits almost all types of freshwater habitats, from small puddles to large lakes, primarily favoring the vegetation-rich littoral zone.
Details
Identification
Spherical body shape, short downward-curved rostrum, shell surface usually smooth or finely reticulated, posterior end of the carapace rounded.
Social behavior
Mostly solitary, but can occur in extremely high individual densities under favorable conditions.
Diet
Feeds by grazing on periphyton (biofilm) and by filtering detritus, bacteria, and fine algal particles.
Hunting strategy
Filter feeder and substrate scraper.
Overwintering
Production of resting eggs (ephippia) that can withstand freezing and desiccation.
Ecology
Ecological role
Important primary consumer and link between microbial production and higher trophic levels.
Natural predators
Juvenile fish, predatory zooplankton (e.g., Cyclops), insect larvae, and water mites.
Competitor species
Other chydorids and small Daphnia species.
Ecosystem service
Contributes to water clarification and serves as an essential food source for fish fry.
Threats
Extreme pesticide pollution and massive habitat loss due to the drainage of small water bodies.
Scientific profile
Profile
Distinguishing features
Short, downward-curved and pointed rostrum; postabdomen is short and broad with 7 to 10 small teeth on the dorsal margin; the valve surface often shows a fine polygonal pattern.
Reproduction
Cyclical parthenogenesis; rapid asexual reproduction under favorable conditions, formation of resting eggs under stress (cold, food scarcity).
Role in food web
Important link in the benthic-littoral food web; converts detritus and bacteria into biomass for higher trophic levels.
Protection & threats
Status not on standard scale
Main threats
No immediate threats known; the species is globally distributed and highly adaptable to anthropogenic influences.