Long-armed water flea
Bosmina longispina
Bosmina longispina is a widespread zooplankton species found in standing freshwater bodies. The species is characterized by a laterally compressed body and distinctive, trunk-like elongated first antennae. It plays an essential role in the pelagic food web as a link between phytoplankton and higher consumers.
Details
Identification
Long, immovable, and downward-curved first antennae; short posterior spine (mucro) on the shell; small head with a large compound eye.
Social behavior
Often occurs in high individual densities but does not exhibit cooperative social behavior.
Diet
Feeds as a filter feeder primarily on unicellular algae, bacteria, and fine organic detritus.
Overwintering
Overwintering usually occurs in the stage of resting eggs (ephippia) on the lake bottom.
Ecology
Ecological role
Important primary consumer that makes phytoplankton biomass available to predatory zooplankton and planktivorous fish.
Natural predators
Juvenile fish, predatory water fleas (e.g., Leptodora), insect larvae.
Competitor species
Other cladocerans such as Daphnia species or Diaphanosoma.
Ecosystem service
Contributes to water clarification by filtering algae.
Threats
Eutrophication, invasive species, and chemical water pollution.
Scientific profile
Profile
Distinguishing features
The antennules are fused to the head shield and curved downwards. Unlike Bosmina longirostris, the mucro in B. longispina is typically significantly longer. Sensory hairs (aesthetascs) are located centrally on the antennule. The terminal claws of the postabdomen feature a specific arrangement of spines.
Reproduction
Cyclical parthenogenesis: During stable phases (summer), asexual reproduction occurs via parthenogenesis. When environmental conditions deteriorate (autumn, food scarcity), males appear and sexual reproduction takes place.
Role in food web
Central role as a primary consumer in the pelagic food web; transfers energy from the microbial loop and phytoplankton to higher trophic levels.
Protection & threats
Main threats
Anthropogenic eutrophication, climate change (rising water temperatures favoring euryoecious species), and invasive predatory invertebrates.