Shield water flea
Sida crystallina
Sida crystallina is a relatively large, nearly transparent water flea from the Sididae family. It possesses a characteristic adhesive organ on the back of its head, which it uses to attach itself to macrophytes in the littoral zone. Unlike many other water fleas, it spends a significant portion of its time sessile on substrates rather than swimming freely in the pelagic zone.
Details
Identification
Nuchal adhesive organ, large oar-like second antennae, six pairs of legs, almost completely transparent body, often found attached to plants.
Social behavior
Mostly solitary while attached to substrates, but can reach very high population densities under favorable conditions.
Diet
Actively filters suspended matter such as phytoplankton, bacteria, and fine detritus from the surrounding water layer.
Hunting strategy
Passive filter feeder; creates a water current through the filter apparatus via rhythmic movements of the phyllopods.
Spawning substrate
Resting eggs are often deposited on aquatic plants or in the sediment.
Overwintering
Overwintering occurs in the egg stage through the production of resting eggs (ephippia) that can withstand freezing and desiccation.
Ecology
Ecological role
Important primary consumer in the littoral zone, transferring energy from algae to higher trophic levels such as fish.
Natural predators
Juvenile fish, predatory insect larvae (e.g., dragonflies), backswimmers, and predatory zooplankton.
Competitor species
Other littoral cladocerans such as Simocephalus vetulus or Eurycercus lamellatus.
Ecosystem service
Supports water clarification by reducing algal blooms and organic suspended matter.
Threats
Loss of macrophytes due to eutrophication, herbicide use, and destruction of shore structures.
Scientific profile
Profile
Distinguishing features
Characterized by a large dorsal adhesive organ (neck organ) on the back of the head used to attach to aquatic plants. It possesses six pairs of thoracic limbs (Ctenopoda) and a large compound eye.
Reproduction
Cyclical parthenogenesis; asexual reproduction during the growing season, formation of males and resting eggs in autumn.
Role in food web
Important primary consumer in the littoral zone; transforms energy from phytoplankton and detritus into biomass for higher trophic levels.
Protection & threats
Main threats
Habitat loss due to eutrophication (decline of macrophytes), shoreline reinforcement, and the use of herbicides.