Expert(s). Expert: Notes: Reference for: Other Source(s). Source: American Fisheries Society Special Publication 31, pre-press (version May). Acquired. PDF | A persisting population of an unidentified and probably undescribed cladoceran, morphologically similar to Daphnia similis CLAUS but genetically. The aim of the present paper is to revise the taxonomy of the Daphnia ( Ctenodaphnia) similis group in the Old World with both morphological.

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Daphniaa genus of small planktonic crustaceansare 0. Daphnia are members of the order Cladoceraand are one of the several small aquatic crustaceans commonly called water fleas because their saltatory Wiktionary swimming style resembles the movements of fleas.

Daphnia simi,is in various aquatic environments ranging from acidic swamps to freshwater lakes and ponds. The two most readily available species of Daphnia are D.

They are often associated with a related genus in the order Cladocera: Moinawhich is in the Moinidae family instead of Daphniidae and is much smaller than D. Daphnia eggs for sale are generally enclosed in ephippia a thick shell, consisting of two chitinous plates, that encloses and protects the winter eggs of a cladoceran.

The body of Daphnia is usually 1—5 millimetres 0.

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In most species, the rest of the body is covered by a carapacewith a ventral gap in which the five or six pairs of legs lie. Even under relatively low-power microscopythe feeding mechanism can be observed, with immature young moving in the brood pouch; moreover, the eye being moved by the ciliary muscles can be seen, as well as blood cells being pumped around the circulatory system by the simple heart.

Daphnialike many animals, are prone to alcohol intoxication, and make excellent subjects for studying the effects of the depressant on the nervous system due to the translucent exoskeleton and the visibly altered heart rate.

They are tolerant of being observed live under a cover slip and appear to suffer no harm when returned to open water. Due to its intermediate size, Daphnia utilizes both diffusion and circulatory methods, producing hemoglobin in low-oxygen environments.

Daphnia is a large genus — comprising over species — belonging to the cladoceran family Daphniidae.

Each subgenus has been further divided into a number of species complexes. The understanding of species boundaries has been hindered by phenotypic plasticity, hybridization, intercontinental introductions and poor taxonomic descriptions. Daphnia species are normally r -selectedmeaning that they invest in early reproduction and so have short lifespans. An individual Daphnia life-span depends on factors such as temperature and the abundance of predatorsbut can be 13—14 months in some cold, oligotrophic fish-free lakes.


Daphnia are typically filter feedersingesting mainly unicellular algae and various sorts of organic detritus including protists and bacteria [3] [10] Beating of the legs produces a constant current through the carapace which brings such material into the digestive tract.

The trapped food particles are formed into a food bolus which then moves down the digestive tract until voided through the anus located on the ventral surface of the terminal appendage.

Swimming is powered mainly by the second set of antennae, which are larger in size than the first set. Most Daphnia species have a life cycle based on “cyclical parthenogenesis”, alternating between parthenogenetic asexual reproduction and sexual reproduction.

They produce a brood of diploid eggs every time they moult ; daphnka broods can contain as few as 1—2 eggs in smaller species, such as D. They are then released into the water, dahpnia pass through a further 4—6 instars over 5—10 days longer in poor conditions before reaching an age where they are able to reproduce.

Daphnia similis Claus, – Overview

Towards the end of the growing season, however, the mode of reproduction changes, and the females produce tough “resting eggs” or “winter eggs”. In species without males, resting eggs are also produced asexually and are diploid. In either case, the resting eggs are protected by a hardened coat called the ephippiumand are cast off at the female’s next moult. The ephippia can withstand sijilis of extreme cold, drought or lack of food availability, and hatch — when conditions improve — into females They are faphnia to being classed as extremophiles.

Several Daphnia species are considered threatened.

The following are listed as eaphnia by IUCN: Daphnia nivalisDaphnia coronataDaphnia occidentalisand Daphnia jollyi. Some species are halophilesand can be found in hypersaline lake environments, an example of which is the Makgadikgadi Pan. They are often fed to tadpoles or small species of amphibians such as the African dwarf frog Similsi boettgeri. Daphnia may be used in certain environments to test the effects of toxins on an ecosystemwhich makes them an indicator genusparticularly useful because of its short lifespan and reproductive capabilities.

Because they are nearly transparent, their internal organs are easy daphina study in live specimens e. Daphnia is also commonly used for experiments to test climate change aspects, as ultraviolet radiation UVR that seriously damage zooplankton species e. Because of their thin membrane, which allows drugs to be absorbed, they are used to monitor the effects of certain simllis, such as adrenaline or capsaicin, on the heart. Some species of daphnia or water fleas that resemble daphnia have developed permanent, non-temporary defenses against fish eating them such as spines and long hooks on the body which also cause them to become entangled daphia fishing lines and cloud water with their high numbers.


Species such as Bythotrephes similos [14] [15] [16] [17] AKA “spiny water flea” and formerly known as Bythotrephes cederstroemi native to Northern Europe and AsiaCercopagis pengoi AKA “fishhook waterflea” native in the brackish fringes of the Black Sea and the Caspian Sea and Daphnia lumholtzi [18] [19] [20] [21] native to east Africa, the Asian subcontinent of India, and east Australia have these characteristics and great care should be taken to prevent them from spreading further in North American waters.

Some species of daphnia native to North America can develop sharp spines at the end of the body and helmet-like structures on the head when they detect predators, [22] [23] but this is overall temporary for such daphnia species and they do not completely overwhelm or discourage native predators from eating them. While daphnia are an important base of the food chain in freshwater lakes and vernal poolsthey become a nuisance when they are unable to be eaten by native macroscopic predators and there is some concern that the original spineless and hookless water fleas and daphnia end up out-competed by the invasive ones.

This may not be the case, however, and the new invaders may mostly be a tangling and clogging nuisance. From Wikipedia, the free encyclopedia. Daphnia Daphnia pulex Scientific classification Kingdom: List of Daphnia species. Petrusek March 2, World checklist of freshwater Cladocera species. Retrieved October 29, The physiology of the Cladocera. Ecology, Epidemiology, and Evolution of Parasitism in Daphnia. National Center for Biotechnology Information. Oneida Lake Education Initiative. Retrieved October 9, Crease; Michael Lynch Molecular Phylogenetics and Evolution.

Zoological Journal of the Linnean Society. In Patrick O’Sullivan; C. Limnology and Limnetic Ecology. Zooplankton of the Great Lakes: Global Invasive Species Database: Stoeckel, Illinois Natural History Survey: The Next Great Lakes Exotic?

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ADW: Daphnia similis: CLASSIFICATION

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