Euastacus
Encyclopedia
Euastacus is a genus
of freshwater
crayfish
known as "spiny crayfish". They are found in the south-east of the Australia
n mainland, along with another genus of crayfish, Cherax
. Both genera are members of the Parastacidae
family, a family of freshwater crayfish restricted to the Southern Hemisphere
.
Euastacus crayfish are distinguished from the smooth-shelled Cherax species by the short robust spikes on their claws and carapace
, and frequently, their larger size. Many Euastacus species grow to a relatively large size, with the Murray River crayfish
(Euastacus armatus) being the second largest freshwater crayfish species in the world. (The largest freshwater crayfish in the world is Tasmanian giant freshwater crayfish
(Astacopsis gouldi), found on the Australian island of Tasmania
, and the Astacopsis genus is now known to be a very closely related sister genus to Euastacus.)
The genera Cherax and Euastacus continue a trend present in many Australian native freshwater fish genera of speciation into generalist lowland
and specialist upland
species. Generally, Cherax species inhabit lowland rivers at low to medium altitudes and swamps and ephemeral waters in inland areas of Australia including the Murray-Darling Basin
. Conversely, Euastacus species are only found in permanent waters and generally inhabit upland rivers at medium to high altitudes in the Murray-Darling Basin as well as many easterly and southerly flowing coastal river systems. The partial exceptions to this are:
Even when found in lowland habitats, these several more adaptable Euastacus crayfish are still highly dependent on reliable flows and good water quality, with good dissolved oxygen levels and low salinity. In constrast to Cherax (yabby) species, Euastacus species are unable to survive drying of their habitats.
The genus Cherax has a far wider distribution than the Euastacus genus, and is found in many parts of Australia including south-western Australia. The Euastacus genus is restricted to the south-east of the Australian mainland. There is a high degree of endemism in Euastacus species in coastal river systems, with many species restricted to single river or creek catchment
. Euastacus species occur in several upland reservoirs.
as critically endangered
(CR), 17 are endangered
(EN), 5 vulnerable
(VU), 1 near threatened
(NT), 8 least concern
(LC) and 1 is data deficient
(DD):
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of freshwater
Fresh Water
Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...
crayfish
Crayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...
known as "spiny crayfish". They are found in the south-east of the Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
n mainland, along with another genus of crayfish, Cherax
Cherax
Cherax is the largest and most widespread genus of fully and partially aquatic crayfish in the Southern Hemisphere. Its members may be found in lakes, rivers and streams across most of Australia and New Guinea. In Australia the many species of Cherax are commonly known as yabbies...
. Both genera are members of the Parastacidae
Parastacidae
Parastacidae is the family of freshwater crayfish found in the southern hemisphere. The family is a classic Gondwana-distributed taxon, with extant members in South America, Madagascar, Australia, New Zealand and New Guinea, and extinct taxa also in Antarctica.Three genera are to be found in Chile,...
family, a family of freshwater crayfish restricted to the Southern Hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
.
Euastacus crayfish are distinguished from the smooth-shelled Cherax species by the short robust spikes on their claws and carapace
Carapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
, and frequently, their larger size. Many Euastacus species grow to a relatively large size, with the Murray River crayfish
Murray crayfish
The Murray crayfish, Euastacus armatus, is a species of freshwater crayfish endemic to Australia that belongs to the family Parastacidae. The Murray crayfish has the largest geographic range of any of the Euastacus crayfish in Australia, being found in the Murray and Murrumbidgee Rivers as well as...
(Euastacus armatus) being the second largest freshwater crayfish species in the world. (The largest freshwater crayfish in the world is Tasmanian giant freshwater crayfish
Tasmanian giant freshwater crayfish
The Tasmanian giant freshwater crayfish is the largest freshwater invertebrate in the world. The species is only found in Tasmania , and is listed as a vulnerable species due to habitat loss and over fishing. It is also severely threatened by siltation and de-snagging of streams as decaying wood...
(Astacopsis gouldi), found on the Australian island of Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
, and the Astacopsis genus is now known to be a very closely related sister genus to Euastacus.)
The genera Cherax and Euastacus continue a trend present in many Australian native freshwater fish genera of speciation into generalist lowland
Upland and lowland (freshwater ecology)
In studies of the ecology of freshwater rivers, habitats are classified as upland and lowland.-Definitions:Upland habitats are cold, clear, rocky, fast flowing rivers in mountainous areas; lowland habitats are warm, slow flowing rivers found in relatively flat lowland areas, with water that is...
and specialist upland
Upland and lowland (freshwater ecology)
In studies of the ecology of freshwater rivers, habitats are classified as upland and lowland.-Definitions:Upland habitats are cold, clear, rocky, fast flowing rivers in mountainous areas; lowland habitats are warm, slow flowing rivers found in relatively flat lowland areas, with water that is...
species. Generally, Cherax species inhabit lowland rivers at low to medium altitudes and swamps and ephemeral waters in inland areas of Australia including the Murray-Darling Basin
Murray-Darling Basin
The Murray-Darling basin is a large geographical area in the interior of southeastern Australia, whose name is derived from its two major rivers, the Murray River and the Darling River. It drains one-seventh of the Australian land mass, and is currently by far the most significant agricultural...
. Conversely, Euastacus species are only found in permanent waters and generally inhabit upland rivers at medium to high altitudes in the Murray-Darling Basin as well as many easterly and southerly flowing coastal river systems. The partial exceptions to this are:
- the Murray River crayfishMurray crayfishThe Murray crayfish, Euastacus armatus, is a species of freshwater crayfish endemic to Australia that belongs to the family Parastacidae. The Murray crayfish has the largest geographic range of any of the Euastacus crayfish in Australia, being found in the Murray and Murrumbidgee Rivers as well as...
which was originally found along the entire length of the Murray RiverMurray RiverThe Murray River is Australia's longest river. At in length, the Murray rises in the Australian Alps, draining the western side of Australia's highest mountains and, for most of its length, meanders across Australia's inland plains, forming the border between New South Wales and Victoria as it...
in addition to many upland habitats, and is still found in the middle reaches of the Murray River - the Glenelg Spiny Crayfish (Eustacus bispinosus), found (or formerly found) in lowland areas of the Glenelg River system and Eight Mile Creek/Ewen Ponds system
- the Gippsland Crayfish (Euastacus kershawi), found in lowland areas of some streams in the Gippsland area.
Even when found in lowland habitats, these several more adaptable Euastacus crayfish are still highly dependent on reliable flows and good water quality, with good dissolved oxygen levels and low salinity. In constrast to Cherax (yabby) species, Euastacus species are unable to survive drying of their habitats.
The genus Cherax has a far wider distribution than the Euastacus genus, and is found in many parts of Australia including south-western Australia. The Euastacus genus is restricted to the south-east of the Australian mainland. There is a high degree of endemism in Euastacus species in coastal river systems, with many species restricted to single river or creek catchment
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
. Euastacus species occur in several upland reservoirs.
Species
Of the 50 species in the genus Euastacus, 17 are on the IUCN Red ListIUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
as critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
(CR), 17 are endangered
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
(EN), 5 vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
(VU), 1 near threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
(NT), 8 least concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
(LC) and 1 is data deficient
Data Deficient
Data Deficient is a category applied by the IUCN, other agencies, and individuals to a species when the available information is not sufficient for a proper assessment of conservation status to be made...
(DD):
- Euastacus armatus (Von Martens, 1866)
- Euastacus australasiensis (H. Milne-Edwards, 1837)
- Euastacus balanesis Morgan, 1988
- Euastacus bidawalis Morgan, 1986
- Euastacus bindal Morgan, 1989
- Euastacus bispinosus Clark, 1936
- Euastacus brachythorax Riek, 1969
- Euastacus clarkae Morgan, 1997
- Euastacus claytoni Riek, 1969
- Euastacus crassus Riek, 1969
- Euastacus dalagarbe Coughran, 2005
- Euastacus dangadi Morgan, 1997
- Euastacus diharawalus Morgan, 1997
- Euastacus diversus Riek, 1969
- Euastacus eungella Morgan, 1988
- Euastacus fleckeri (Watson, 1953)
- Euastacus gamilaroi Morgan, 1997
- Euastacus girurmulayn Coughran, 2005
- Euastacus gumar Morgan, 1997
- Euastacus guruhgi Coughran, 2005
- Euastacus guwinus Morgan, 1997
- Euastacus hirsutus (McCulloch, 1917)
- Euastacus hystricosus Riek, 1951
- Euastacus jagabar Coughran, 2005
- Euastacus jagaraEuastacus jagaraEuastacus jagara is a species of Australian crayfish in the family Parastacidae. It is known from only six specimens, all collected at the type locality in the Mistake Mountains in the State of Queensland, Australia. The streams inhabited by the species are surrounded by Upland Subtropical...
Morgan, 1988 - Euastacus kershawi Smith, 1912
- Euastacus maccai McCormack & Coughran, 2008
- Euastacus maidaeEuastacus maidaeEuastacus maidae is a species of Australian crayfish in the family Parastacidae. It is known only from a single catchment in the Gold Coast hinterland in the State of Queensland, Australia, and is listed as critically endangered on the IUCN Red List. The stream is surrounded by Subtropical...
(Riek, 1956) - Euastacus mirangudjin Coughran, 2002
- Euastacus monteithorum Morgan, 1989
- Euastacus morgani Coughran & McCormack, 2011
- Euastacus neodiversus Riek, 1969
- Euastacus neohirsutus Riek, 1956
- Euastacus pilosus Coughran & Leckie, 2007
- Euastacus polysetosus Riek, 1951
- Euastacus reductus Riek, 1969
- Euastacus rieki Morgan, 1997
- Euastacus robertsi Monroe, 1977
- Euastacus setosus (Riek, 1956)
- Euastacus simplex Riek, 1956
- Euastacus spinichelatus Morgan, 1997
- Euastacus spinifer (Heller, 1865)
- Euastacus sulcatusEuastacus sulcatusEuastacus sulcatus is a freshwater crayfish, or yabby. It is bright blue in colour and roams the forest floor when conditions are damp.-Distribution:...
Riek, 1951 - Euastacus suttoni Clark, 1941
- Euastacus urospinosus (Riek, 1956)
- Euastacus valentulus Riek, 1951
- Euastacus wiowuru Morgan, 1986
- Euastacus yanga Morgan, 1997
- Euastacus yarraensis (McCoy, 1888)
- Euastacus yigara Short & Davie, 1993