The Diplostraca or Cladocera, commonly known as water fleas, is a superorder of small, mostly freshwater , most of which feed on microscopic chunks of organic matter, though some forms are predatory.
Over 1000 species have been recognised so far, with many more undescribed.
Description
They are mostly long, with the exception of
Leptodora, which can be up to long.
The body is not obviously segmented and bears a folded
carapace which covers the thorax and
abdomen.
The head is angled downwards, and may be separated from the rest of the body by a "cervical sinus" or notch.
The mouthparts are small, and consist of an unpaired labrum, a pair of mandibles, a pair of maxillae, and an unpaired labium.
The thorax bears five or six pairs of lobed, leaf-like appendages, each with numerous hairs or setae.
Lifecycle
With the exception of a few purely asexual species, the lifecycle of diplostracans is dominated by asexual reproduction, with occasional periods of sexual reproduction; this is known as cyclical parthenogenesis.
When conditions are favourable, reproduction occurs by parthenogenesis for several generations, producing only female
Cloning. As the conditions deteriorate, males are produced, and sexual reproduction occurs. This results in the production of long-lasting dormant eggs. These
ephippial eggs can be transported over land by wind, and hatch when they reach favourable conditions, allowing many species to have very wide – even cosmopolitan – distributions.
Except for the genus Leptodora, which has a
metanauplius stage, a nauplius larval stage is absent in Diplostraca.
[ Thorp and Covich's Freshwater Invertebrates: Keys to Nearctic Fauna]
Evolutionary history
Diplostraca are nested within the
clam shrimp, being most closely related to the order Cyclestherida, the only living genus of which is
Cyclestheria. Though several fossils from the
Paleozoic have been claimed to represent fossils of diplostracans, none of these records can be confirmed. The oldest confirmed records of diplostracans are from the Early
Jurassic of Asia. Fossils from the Jurassic are assignable to modern as well as extinct groups, indicating that the initial radiation of the group occurred prior to the beginning of the Jurassic, likely during the late
Paleozoic.
A Devonian to Carboniferous genus,
Ebullitiocaris, is tentatively placed as a diplostracan, however since it is only known from carapaces this is uncertain.
[
]
Ecology
Most diplostracan species live in fresh water and other inland water bodies, with only eight species being truly neritic zone.
Taxonomy
According to the World Registry of Marine Species, Cladocera is a synonym of the superorder Diplostraca, which is included in the class Branchiopoda. Both names are currently in use. The superorder forms a monophyly of 7 orders, about 24 families, and more than 11,000 species. Many more species remain undescribed.[ ] The genus Daphnia alone contains around 150 species.
The following families are recognised:
Superorder Diplostraca Gerstaecker, 1866 (=Cladocera)
- Order Anomopoda G.O. Sars, 1865
- : Family Acantholeberidae Smirnov, 1976
- : Family Bosminidae Baird, 1845
- : Family Chydoridae Dybowski & Grochowski, 1894
- : Family Daphniidae Straus, 1820
- : Family Dumontiidae Santos-Flores & Dodson, 2003
- : Family Eurycercidae Kurz, 1875
- : Family Gondwanothrichidae Van Damme, Shiel & Dumont, 2007
- : Family Ilyocryptidae Smirnov, 1976
- : Family Macrothricidae Norman & Brady, 1867
- : Family Moinidae Goulden, 1968
- : Family Ophryoxidae Smirnov, 1976
- Order Ctenopoda G.O. Sars, 1865
- : Family Holopediidae G.O. Sars, 1865
- : Family Pseudopenilidae Korovchinsky & Sergeeva, 2008
- : Family Sididae Baird, 1850
- Order Cyclestherida Sars G.O., 1899
- : Family Cyclestheriidae Sars G.O., 1899
- Order Haplopoda G.O. Sars, 1865
- : Family Leptodoridae Lilljeborg, 1861
- Order Laevicaudata Linder, 1945
- : Family Lynceidae Stebbing, 1902
- Order Onychopoda G.O. Sars, 1865
- : Family Cercopagididae Mordukhai-Boltovskoi, 1968
- : Family Podonidae Mordukhai-Boltovskoi, 1968
- : Family Polyphemidae Baird, 1845
- Order Spinicaudata Linder, 1945
- : Family Cyzicidae Stebbing, 1910
- : Family Eocyzicidae Schwentner, et al., 2020
- : Family Leptestheriidae Daday, 1913: 44
- : Family Limnadiidae Burmeister, 1843
Etymology
The word "Cladocera" derives via Neo-Latin from the Ancient Greek κλάδος]] ( kládos, "branch") and κέρας]] ( kéras, "horn").
See also
-
Bythotrephes longimanus (invasive species) formerly''
] - Spiny Water Flea
[(April 16, 2013) NorthAmericanFishing - "Silent Invaders" Spiny Water Flea PT 1 2013 ]
Cercopagis pengoi (invasive species)
Daphnia lumholtzi (invasive species)
Moina (smallest)
Zooplankton
-
Brusca, R.C.; Brusca, G.J. (1990). Invertebrates. Sinauer Associates: Sunderland, MA (USA). ISBN 0-87893-098-1. 922 pp
-
Martin, J.W., & Davis, G.E. (2001). An updated classification of the recent Crustacea. Science Series, 39. Natural History Museum of Los Angeles County. Los Angeles, CA (USA). 124 pp.
-
Norambuena, J., J. Farías & P. De los Ríos. (2019). he water flea Daphnia pulex (Cladocera, Daphniidae), a possible model organism to evaluate aspects of freshwater ecosystems. Crustaceana, (11-12): 1415-1426.
External links
-
Cladocera – Guide to the Marine Zooplankton of South Eastern Australia
