water flea


water flea
any of various small crustaceans that move about in the water like fleas, as those of the genus Daphnia.
[1575-85]

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Any of about 450 species (order Anomopoda) of microscopic, mostly freshwater crustaceans distributed worldwide.

Species in the genus Daphnia are ubiquitous in Europe and North America. Water fleas have a discrete head that bears antennae. The carapace (shell) encloses all or most of the body, except on the predatory giant Leptodora (up to 0.7 in. [18 mm] long), whose carapace is just a small brood sac. Most species swim by powerful strokes of the antennae, sometimes producing a hopping-and-sinking motion. All but a few predatory species use specialized thoracic limbs to filter organic matter from the water. See also copepod.

Water flea of the genus Daphnia (magnified about 30×)

Eric V. Grave
Photo Researchers

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 any member of the crustacean order Anomopoda (class Branchiopoda), a large group containing about 450 species distributed worldwide. Most forms are found in freshwater habitats, but a few occur in marine environments. The best known genus is Daphnia, ubiquitous in ponds and streams in Europe and North America. The water flea is microscopic in size, typically measuring only about 0.2 to 3.0 millimetres (0.01 to 0.12 inch) long. It has a discrete head bearing antennae and a bivalve carapace that encloses all or most of the trunk and abdomen. An exception is the predatory giant Leptodora, which grows as long as 18 mm and whose carapace is reduced to a small brood sac. Most species swim by means of powerful strokes of the antennae; in some species the successive strokes produce a characteristic hopping and sinking motion. Apart from a few predatory forms, water fleas feed on microscopic particles of organic matter, which they filter from the water with specialized thoracic limbs. They in turn are eaten by fish. Certain water fleas provide, for example, the basic food of nearly all commercial fishes of the Great Lakes of North America.

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Universalium. 2010.

Look at other dictionaries:

  • Water flea — is a generic term for a number of small aquatic crustacea characterised by their jumping or jerky mode of swimming. Most are between 0.1 mm and 3 mm in length. Most commonly, they will be species of Daphnia but a number of other genera are also… …   Wikipedia

  • Water flea — Wa ter flea (Zo[ o]l.) Any one of numerous species of small aquatic Entomostraca belonging to the genera {Cyclops}, {Daphnia}, etc; so called because they swim with sudden leaps, or starts. [1913 Webster] …   The Collaborative International Dictionary of English

  • water flea — n. any of an order (Cladocera) of mostly freshwater branchiopods; esp., any of a genus (Daphnia) commonly found in ponds and used to feed fish in aquariums …   English World dictionary

  • water flea — wa′ter flea n. ivt any tiny freshwater branchiopod crustacean of the order Cladocera, as the daphnia • Etymology: 1575–85 …   From formal English to slang

  • water flea — noun 1. minute free swimming freshwater copepod having a large median eye and pear shaped body and long antennae used in swimming; important in some food chains and as intermediate hosts of parasitic worms that affect man e.g. Guinea worms • Syn …   Useful english dictionary

  • water flea — noun Date: circa 1585 any of various small active dark or brightly colored aquatic crustaceans (as a daphnia or cyclops) …   New Collegiate Dictionary

  • water flea — Daphnia are used as food for fish in aquaria …   Dictionary of ichthyology

  • water flea — noun Any of various aquatic crustacea characterised by their jumping or jerky mode of swimming; mostly species of Daphnia …   Wiktionary

  • water flea — noun another term for daphnia …   English new terms dictionary

  • water flea — /ˈwɔtə fli/ (say wawtuh flee) noun any of various small aquatic crustaceans of the order Cladocera, as the C. daphnia, which swim with characteristically jerky movements …   Australian English dictionary


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