''Cherax'', commonly known as yabby/yabbies in Australia, is the most widespread

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of fully aquatic crayfish in the Southern Hemisphere. Various species of cherax may be found in both still and flowing bodies of freshwater across most of Australia and

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torr ...

. Together with '' Euastacus'', it is also the largest crayfish genus in the Southern Hemisphere.

Habitat

Members of the cherax genus can be found in

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of w ...

s, and streams across most of Australia and New Guinea. The most common and widely distributed species in Australia is the

common yabby The common yabby (''Cherax destructor'') is an Australian freshwater crustacean in the Parastacidae family. It is listed as a vulnerable species of crayfish by the International Union for Conservation of Nature (IUCN), though wild yabby popula ...

(''C. destructor''). It is generally found in

lowland Upland and lowland are conditional descriptions of a plain based on elevation above sea level. In studies of the ecology of freshwater rivers, habitats are classified as upland or lowland. Definitions Upland and lowland are portions of p ...

rivers and streams, lakes, swamps, and impoundments at low to medium altitude, largely within the

Murray–Darling Basin The Murray–Darling basin is a large geographical area in the interior of southeastern Australia, encompassing the drainage basin of the tributaries of the Murray River, Australia's longest river, and the Darling River, a right tributary of ...

. Common yabbies are found in many ephemeral waterways, and can survive dry conditions for long periods of time (at least several years) by aestivating (lying dormant) in burrows sunk deep into muddy creek and swamp beds. In New Guinea, ''Cherax'' crayfish are found widely in rivers, streams, and lakes, with a particularly high diversity in the Paniai Lakes. New Guinea is also home to the only known cave-living crayfish in the Southern Hemisphere, ''C. acherontis''.

Introduced

Some species are very colourful and sometimes seen in the freshwater aquarium trade.

Reproduction

The mating season for ''Cherax'' is during early spring. After fertilisation, eggs develop inside the mother’s body for 4 to 6 weeks. After that period, the eggs transition to the outside of the mother's body and rest on the female’s tail. Then the eggs continue to develop and hatch in spring. Both sexes of ''Cherax'' are selective with copulation partners. Females tend to choose males with a larger central mass (abdomen and tail) and

cheliped A chela ()also called a claw, nipper, or pinceris a pincer-like organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through New Latin '. The plural form is chelae. Legs bearing a chela are called chelipeds. ...

. Males tend to select copulation partners who have larger body sizes and are virgins. Opposed to females who were more dominant or had symmetrical chelipeds. As part of a mating/copulation ritual, males and females fight each other. This allows the female to test the strength of the male to determine if they will produce profitable offspring. During the fight both release urine. The female’s release of urine triggers a sexual response from the male. The male's release of urine is an aggressive response towards the fight with the female. When the male smells the female's urine it will stop releasing its own, hoping the female will allow them to copulate. Once the female has allowed the male to deposit its sperm. The male will position itself on its back and deposit its sperm. Unlike other crayfish species, the ''Cherax dispar'' does not use its cheliped to cage females during copulation. It is mainly used during mating when the males and females fight.

Behaviour

In instances when displaying males have chelae of a similar size, they will engage in combat and those with the greater chelae closing force will win. Female ''C. dispar'' uses honest signalling of strength meaning the size of their chelae is a good indication to other ''C. dispar'' about that individual's strength. Individuals possessing larger chelae engage in more agonistic encounters and are also more likely to win. In a study of female C''. dispar'' chelae strength, they found that chelae size also indirectly indicated the dominance of the female because of its honest indication of strength.

Species

The genus contains 59 species: *'' Cherax acherontis'' Patoka, Bláha & Kouba, 2017 *'' Cherax albertisii'' Nobili, 1899 *'' Cherax albidus'' Clarke, 1936 *'' Cherax angustus'' *'' Cherax aruanus'' Roux, 1911 *'' Cherax austini'' Coughran & Hobson, 2012 *'' Cherax barretti'' Clark, 1941 *'' Cherax bicarinatus'' (Gray, 1845) *'' Cherax boesemani'' Lukhaup & Pekny, 2008 *'' Cherax boschmai'' Holthuis, 1949 *'' Cherax buitendijkae'' Holthuis, 1949 *'' Cherax cainii'' Austin, 2002 *'' Cherax cairnsensis'' Riek, 1969 *'' Cherax cartalacoolah'' Short, 1993 *'' Cherax cid'' Coughran & Furse, 2012 *'' Cherax communis'' Holthuis, 1949 *'' Cherax crassimanus'' Riek, 1967 *'' Cherax cuspidatus'' Riek, 1969 *'' Cherax davisi'' Clark, 1941 *'' Cherax depressus'' Riek, 1951 *'' Cherax destructor'' Clark, 1936 *'' Cherax dispar'' Riek, 1951 *'' Cherax esculus'' Riek, 1956 *'' Cherax gherardii'' Patoka, Bláha & Kouba, 2015 *'' Cherax glaber'' Riek, 1967 *'' Cherax glabrimanus'' Riek, 1967 *'' Cherax gladstonensis'' Riek, 1969 *'' Cherax holthuisi'' Lukhaup & Pekny, 2006 *'' Cherax leckii'' Coughran, 2005 *'' Cherax longipes'' Holthuis, 1949 *'' Cherax lorentzi'' Roux, 1911 *'' Cherax minor'' Holthuis, 1996 *'' Cherax misolicus'' Holthuis, 1949 *'' Cherax monticola'' Holthuis, 1950 *'' Cherax murido'' Holthuis, 1949 *'' Cherax neocarinatus'' Riek, 1967 *'' Cherax neopunctatus'' Riek, 1969 *'' Cherax nucifraga'' Short, 1991 *'' Cherax pallidus'' Holthuis, 1949 *'' Cherax paniaicus'' Holthuis, 1949 *'' Cherax papuanus'' Holthuis, 1949 *'' Cherax parvus'' Short & Davie, 1993 *'' Cherax peknyi'' Lukhaup & Herbert, 2008 *'' Cherax plebejus'' (Hess, 1865) *'' Cherax preissii'' (Erichson, 1846) *'' Cherax pulcher'' Lukhaup, 2015 *'' Cherax punctatus'' Clark, 1936 *'' Cherax quadricarinatus'' (von Martens, 1868) *'' Cherax quinquecarinatus'' (Gray, 1845) *'' Cherax rhynchotus'' Riek, 1951 *'' Cherax robustus'' Riek, 1951 *'' Cherax rotundus'' Clark, 1941 *'' Cherax setosus'' (Riek, 1951) *'' Cherax snowden'' Lukhaup, Panteleit & Schrimpf, 2015 *'' Cherax solus'' Holthuis, 1949 *'' Cherax tenuimanus'' (Smith, 1912) *'' Cherax urospinosus'' Riek, 1969 *'' Cherax wagenknechtae'' Eprilurahman / Lukhaup, 2022 *'' Cherax wasselli'' Riek, 1969

References

* {{Taxonbar, from=Q2702517 Parastacidae Decapod genera