Cladocera

This is the sighted version that was marked on October 31, 2020. There are 2 pending changes that still need to be sighted.

Water fleas in the broader sense is the colloquial term for a number of small crustaceans from various families and genera. These crustaceans do not form a closely related group, but are so called because of their small size and hopping mode of locomotion in water. However, the mode of locomotion differs among the various groups called water fleas.

Water fleas in the narrower sense used to include the group Cladocera within the clawed tails (Onychura). The species common water flea (Daphnia pulex) belongs to this group. The closely related species large water flea (Daphnia magna) is used for water quality studies. Daphnia belong to the gill-foot crabs and live mainly in plankton. They move by beating their two-branched 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-foot crabs, and Polyphemus pediculus, which occurs in swarms in the water column, have 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 its antennae.

In the case of the hop-footed crustaceans, the intermittent rowing with their first antennae also gives 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 widespread species such as the common amphipod, the stream amphipod and the crayfish. These amphipods live at the bottom of water bodies, often under stones or wood, where they feed on foliage and plant parts.

Water fleas occur in large numbers in nature depending on the season and form an important food source for fish. Most species are easy to breed and can function as live food for aquarium fish, among other things. They can also proliferate in very enclosed systems such as barrels. They feed on plants and fungi.