Harpacticoida is an

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

copepod Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (living in the water column), some are benthos, benthic (living on the sedimen ...

s, in the

subphylum In zoological nomenclature, a subphylum is a taxonomic rank below the rank of phylum. The taxonomic rank of " subdivision" in fungi and plant taxonomy is equivalent to "subphylum" in zoological taxonomy. Some plant taxonomists have also used th ...

Crustacea Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

. This order comprises 463

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

and about 3,000

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

; its members are

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

s found throughout the world in the marine environment (most families) and in

fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salt (chemistry), salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include ...

(essentially the

Ameiridae Ameiridae is a family of crustaceans belonging to the order Harpacticoida Harpacticoida is an Order (biology), order of copepods, in the subphylum Crustacean, Crustacea. This order comprises 463 genus, genera and about 3,000 species; its membe ...

Parastenocarididae Parastenocarididae is a family of copepods in the order Harpacticoida adapted to life in groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, ro ...

and the

Canthocamptidae Canthocamptidae is a family (biology), family of copepods. Most of the 700 species are confined to fresh water, although there are also marine species. It contains the following genera: *''Afrocamptus'' Chappuis, 1932 *''Antarctobiotus'' Chappui ...

). A few of them are

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

ic or live in association with other organisms. Harpacticoida represents the second-largest

meiofauna Meiobenthos, also called meiofauna, are small benthic invertebrates that live in marine or freshwater environments, or both. The term ''meiofauna'' loosely defines a group of organisms by their sizelarger than microfauna but smaller than macrof ...

l group in

marine sediment Marine sediment, or ocean sediment, or seafloor sediment, are deposits of insoluble particles that have accumulated on the seafloor. These particles either have their origins in soil and Rock (geology), rocks and have been Sediment transport, ...

s, after

nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...

s. In Arctic and Antarctic seas, Harpacticoida are common inhabitants of

sea ice Sea ice arises as seawater freezes. Because ice is less density, dense than water, it floats on the ocean's surface (as does fresh water ice). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Much of the world' ...

. The name Harpacticoida comes from the Greek noun ''harpacticon'' (rapacious predator) and the suffix ''-oid'' (akin to) and means ''reminiscent of a predator'' . Harpacticoids are distinguished from other copepods by the presence of only a very short pair of first antennae. The second pair of antennae are biramous, and the major joint within the body is located between the fourth and fifth body segments. They typically have a wide

abdomen The abdomen (colloquially called the gut, belly, tummy, midriff, tucky, or stomach) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal ...

, and often have a somewhat worm-like body.

Families

53 families are currently recognised in the Harpacticoida: *

Adenopleurellidae Adenopleurellidae is a family of crustaceans belonging to the order Harpacticoida Harpacticoida is an Order (biology), order of copepods, in the subphylum Crustacean, Crustacea. This order comprises 463 genus, genera and about 3,000 species; i ...

* Aegisthidae *

* Ancorabolidae * Arenopontiidae * Argestidae * Balaenophilidae *

* Chappuisiidae *

Cletodidae Cletodidae is a family of copepods belonging to the order Harpacticoida Harpacticoida is an Order (biology), order of copepods, in the subphylum Crustacean, Crustacea. This order comprises 463 genus, genera and about 3,000 species; its members ...

Cletopsyllidae Cletopsyllidae is a family of crustaceans belonging to the order Harpacticoida Harpacticoida is an Order (biology), order of copepods, in the subphylum Crustacean, Crustacea. This order comprises 463 genus, genera and about 3,000 species; its ...

Cristacoxidae Cristacoxidae is a family of crustaceans belonging to the order Harpacticoida Harpacticoida is an Order (biology), order of copepods, in the subphylum Crustacean, Crustacea. This order comprises 463 genus, genera and about 3,000 species; its m ...

Cylindropsyllidae Cylindropsyllidae is a family of copepods belonging to the order Harpacticoida Harpacticoida is an Order (biology), order of copepods, in the subphylum Crustacean, Crustacea. This order comprises 463 genus, genera and about 3,000 species; its ...

Dactylopusiidae Dactylopusiidae is a family of copepods belonging to the order Harpacticoida Harpacticoida is an Order (biology), order of copepods, in the subphylum Crustacean, Crustacea. This order comprises 463 genus, genera and about 3,000 species; its me ...

Darcythompsoniidae Darcythompsoniidae is a family (biology), family of copepods, containing four genera. Members of the family have a very wide distribution throughout the tropics, where they live in rotting mangrove leaves. They lack egg sacs and are thought to la ...

* Ectinosomatidae * Hamondiidae * Harpacticidae * Idyanthidae * Laophontidae * Laophontopsidae * Latiremidae * Leptastacidae * Leptopontiidae * Louriniidae * Metidae *

Miraciidae Miraciidae is a family (biology), family of copepods in the family Miraciidae. Subdivisions The World Register of Marine Species lists the following genera as accepted within Miraciidae, subdivided into three subfamilies. References

...

* Nannopodidae * Neobradyidae * Normanellidae * Novocriniidae * Orthopsyllidae * Parameiropsidae * Paramesochridae * Parastenheliidae *

* Peltidiidae * Phyllognathopodidae * Pontostratiotidae * Porcellidiidae * Protolatiremidae * Pseudotachidiidae * Rhizothricidae * Rometidae * Rotundiclipeidae * Superornatiremidae * Tachidiidae * Tegastidae * Tetragonicipitidae * Thalestridae * Thompsonulidae * Tisbidae * Zosimeidae

References

External links

Harpacticoida, Guide to the marine zooplankton of south eastern AustraliaTasmanian Aquaculture and Fisheries Institute
* {{Authority control Crustacean orders