A number of small crustaceans from different families and genera is colloquially referred to as water fleas in the broader sense . These crustaceans do not form a closely related group, but are so called because of their small size and the way they move around in water. However, the mode of locomotion is different for the different groups called water fleas.
As water fleas in the narrower sense, the group of the Cladocera within the claw tails (Onychura) used to be summarized. This group includes the type Daphnia pulex ( Daphnia pulex ). The closely related species large water flea ( Daphnia magna ) is used for water quality tests. The daphnia belong to the gill pods and live mainly in plankton . They move by beating their two-armed second antennae, on which long bristles fan out with each swimming movement. The flat-headed water flea ( Simocephalus vetulus ), which also belongs to the gill-pods, and the Polyphemus pediculus, which occurs in swarms within the water column, show a similar way of life .
The genus Bosmina also belongs to the claw tails. Bosmina longirostris lives worldwide on the ground or in the mud of the shore zones of lakes and ponds. Bosmina can also swim short distances with the help of her antennae.
With the hoppers , the intermittent rowing with their first antennae also creates the impression of a flea-like hopping. These small crustaceans belong to the copepods , many species also live in the zooplankton .
The amphipods include many common species such as the common amphipod , river amphibians, and river amphibians . These amphipods live at the bottom of the water, often under stones or wood, where they feed on leaves and parts of plants.
Water fleas occur in large numbers in nature, depending on the season, and are an important source of food for fish. Most species are easy to breed and can, among other things, a. act as live food for aquarium fish. They can also spread in very closed systems like tons. They feed on plants and fungi.
- "Microbiological Studies - The Water Flea" (1920) - recording from the collection of the Federal Institute for Scientific Film (ÖWF) in the online archive of the Austrian Media Library