Toothed rotifer
Brachionus calyciflorus
The toothed rotifer is a widespread freshwater zooplankton characterized by a rigid shell (lorica) with prominent anterior spines or teeth. It moves and feeds using a ciliary corona that creates water currents to filter food particles. This species exhibits significant cyclomorphosis, where spine length can change in response to chemical signals from predators.
Details
Identification
Four spines on the anterior margin of the lorica, transparent shell, round to oval body shape, often seen carrying eggs at the foot.
Social behavior
Solitary, but forms very dense populations when food availability is high.
Diet
Primarily feeds on phytoplankton (unicellular algae), bacteria, and fine detritus.
Hunting strategy
Filter feeder; uses its ciliary corona to create a water current that directs food particles to the mouth.
Spawning substrate
Eggs are usually carried on the foot of the female or released directly into the water.
Overwintering
Formation of thick-shelled resting eggs (cysts) that survive in the sediment.
Ecology
Ecological role
Important link in the food web between primary producers and small fish.
Natural predators
Predatory rotifers (e.g., Asplanchna), copepods, and fish larvae.
Competitor species
Other filtering zooplankton such as Daphnia or other Brachionus species.
Ecosystem service
Contributes to the control of algal blooms and nutrient recycling in water bodies.
Threats
Eutrophication, chemical water pollution, and invasive species.
Scientific profile
Profile
Distinguishing features
Four spines on the anterior margin of the lorica; pronounced phenotypic plasticity (cyclomorphosis), where posterior spines are developed as a defense response to predator kairomones (e.g., from Asplanchna).
Reproduction
Cyclical parthenogenesis: Predominantly asexual reproduction by amictic females; environmental stress (high density, cold) triggers a sexual phase involving mictic females.