Conondale spiny crayfish (Euastacus hystricosus)

Description

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Conondale spiny crayfish fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
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Conondale spiny crayfish description

The Conondale spiny crayfish (Euastacus hystricosus) is a large freshwater crayfish found only in Queensland, Australia ^{(1) (3) (4) (5)}. Like other members of the genus Euastacus, it is characterised by its spiny appearance ^{(2) (3) (4)}, with the spines of this species being particularly numerous, large and sharp ^{(2) (4) (6)}.

The Conondale spiny crayfish has a dark green body, with a paler underside, dull reddish legs joints, and large, reddish-brown, pincer-like claws ^{(4) (7)}. The spines on the abdomen are reddish or whitish, with darker tips ⁽⁷⁾. However, Euastacus species can be quite variable in appearance, sometimes making identification difficult ⁽⁸⁾.

As in other crayfish species, the body of the Conondale spiny crayfish is protected by a hard carapace. The abdomen is divided into six segments and ends in a tail fan, which is composed of a central flap (telson) and surrounding flaps known as uropods. Crayfish have five pairs of appendages on the thorax, the first pair being modified into the large claws (chelae), with the remainder, known as ‘pereiopods’, being used for feeding and walking. Further appendages on the abdomen, known as ‘pleopods’ or ‘swimmerets’, are used in swimming and also by the female for brooding eggs ^{(9) (10)}.

On its head, a crayfish bears a pair of compound eyes, several feeding appendages, and two pairs of antennae, the smaller, central pair of which are known as ‘antennules’ ^{(9) (10)}.

Also known as

Conondale spiny cray.

Size

Occipital carapace length: up to 13.9 cm ⁽²⁾

Conondale spiny crayfish biology

There is relatively little specific information available on the biology of the Conondale spiny crayfish. However, like other Euastacus species, it digs burrows under logs and rocks, both above and below the water level ^{(1) (3) (5) (6) (9)}. Juvenile Conondale spiny crayfish are generally found in shallower water, away from the deep areas preferred by larger individuals and by predators such as eels and large shrimps ⁽⁶⁾.

The Conondale spiny crayfish may be active during the day in deeper, darker areas of water, but it is more commonly active at night, particularly in smaller, shallower, clear streams ⁽⁶⁾. As in other freshwater crayfish, its diet is likely to include a variety of plant and animal matter, as well as detritus ⁽⁹⁾.

Unlike many marine species, freshwater crayfish do not have a long, planktonic larval stage. Instead, they produce large eggs which are incubated on the pleopods of the female before hatching into miniature versions of the adult ^{(9) (10)}. In the Conondale spiny crayfish, females reach maturity at an occipital carapace length of about six centimetres ⁽²⁾.

Conondale spiny crayfish range

The Conondale spiny crayfish is endemic to southeast Queensland, Australia. It is known from streams in the Brisbane and Mary River Catchments, on and around the Maleny Plateau in the Conondale and nearby Blackall Ranges ^{(1) (3) (4) (5)}.

Although this species occurs in a number of streams, it is restricted to the few headwater areas above elevations of 475 metres, and therefore has a highly restricted and fragmented distribution ^{(1) (5)}.

Conondale spiny crayfish habitat

Like other Euastacus species, the Conondale spiny crayfish prefers heavily shaded, well oxygenated waters. It is a freshwater species that inhabits cool, clear, flowing headwater streams in mountains, in both rainforest and wet sclerophyll forest ^{(1) (2) (5)}.

Conondale spiny crayfish status

The Conondale spiny crayfish is classified as Endangered (EN) on the IUCN Red List ⁽¹⁾.

Conondale spiny crayfish threats

The Conondale spiny crayfish has a highly fragmented distribution, and the mountain streams it inhabits are declining in quality due to the destruction of surrounding rainforest habitat and the effects of introduced species. Feral pigs cause damage by rooting and by destroying crayfish burrows, while other non-native species, such as cats, foxes and the cane toad (Bufo marinus), may also affect Conondale spiny crayfish populations ^{(1) (5)}.

A further threat to the habitat of this species comes from climate change, which may result in increased temperatures, altered water regimes, more severe weather events and the loss of suitable cool, highland habitat ^{(1) (5)}. As the Conondale spiny crayfish depends on a quite restricted habitat in cool, mountainous areas, even a slight increase in temperature could significantly reduce its range ⁽¹⁾. Its restricted distribution also puts it at increased risk from localised events such as bushfires and unsuitable forest management practices ⁽¹⁾.

Being a large species that is likely to appeal to recreational fishers, the Conondale spiny crayfish is also potentially under threat from illegal fishing pressure, despite being protected by a ‘no take’ policy ^{(1) (5) (6)}. The taking of large, mature adults may seriously impact on the population structure and reproductive success of this species ^{(1) (5)}.

Conondale spiny crayfish conservation

There are no specific conservation measures currently targeted at the Conondale spiny crayfish ^{(1) (5)}. However, it is found within several national parks and state forests, and all Euastacus species are officially ‘no take’ species in Queensland, although illegal poaching does occur ^{(1) (5)}.

Recommended conservation measures for this large freshwater crayfish include research into its populations, biology, habitat requirements and life history, and further investigations into its response to various threats ^{(1) (5)}.

In 2005, the Australian Crayfish Project (ACP) was started with the aim of surveying, identifying and documenting all of Australia’s freshwater crayfish species, including the Conondale spiny crayfish. It is hoped that the information generated by this project will help in the conservation of freshwater crayfish species and their habitats throughout Australia ⁽⁸⁾.

Find out more

Find out more about freshwater crayfish conservation in Australia:

• Australian Aquatic Biological Pty Limited - Australian Crayfish Project:
  http://www.aabio.com.au/crayfish.html

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Glossary

Abdomen

In arthropods (crustaceans, insects and arachnids) the abdomen is the hind region of the body, which is usually segmented to a degree (but not visibly in most spiders). In crustacea (such as crabs) some of the limbs attach to the abdomen; in insects the limbs are attached to the thorax (the part of the body nearest to the head) and not the abdomen.

Antennae

Pair of sensory structures on the head of invertebrates.

Carapace

In arthropods (insects, crabs, etc), the fused head and thorax (the part of the body located near the head), also known as the ‘cephalothorax’.

Detritus

Litter formed from fragments of dead material.

Endemic

A species or taxonomic group that is only found in one particular country or geographic area.

Feral

Previously domesticated animals that have returned to a wild state.

Genus

A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.

Incubation

The act of incubating eggs; that is, keeping them warm so that development is possible.

Larval

Of the stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.

Occipital carapace length

A measurement used for species such as crayfish, taken as the length between the eyes and the rear of the carapace.

Plankton

Aquatic organisms, usually tiny, that drift passively with water movements; may be phytoplankton (plants), zooplankton (animals), or other organisms such as bacteria.

Sclerophyll

A type of vegetation with hard, thick-skinned leaves; for example, eucalypts and acacias.

Thorax

Part of the body located between the head and the abdomen in animals.

References

1. IUCN Red List (June, 2011)
   http://www.iucnredlist.org/
2. Coughran, J. (2008) Distinct groups in the genus Euastacus? Freshwater Crayfish, 16: 123-130.
3. Riek, E.F. (1969) The Australian freshwater crayfish (Crustacea: Decapoda: Parastacidae), with descriptions of a new species. Australian Journal of Zoology, 17(5): 855-918.
4. Riek, E.F. (1951) The freshwater crayfish (family Parastacidae) of Queensland. Records of the Australian Museum, 22(4): 368-388.
5. Coughran, J. and Furse, J.M. (2010) An Assessment of Genus Euastacus (49 Species) Versus IUCN Red List Criteria. A Report Prepared for the Global Species Conservation Assessment of Lobsters and Freshwater Crayfish for the IUCN Red List of Threatened Species. Environmental Futures Centre, Griffith University, Queensland, Australia. Available at:
   http://iz.carnegiemnh.org/crayfish/IAA/docs/Coughran_and_Furse_2010.pdf
6. Australian Aquatic Biological Pty Limited (2009) The Conondale Spiny Cray Euastacus hystricosus. AAB Newsletter, 3: 8.
7. Riek, E.F. (1956) Additions to the Australian freshwater crayfish. Records of the Australian Museum, 24(1): 1-6.
8. Australian Aquatic Biological Pty Limited - Australian Crayfish Project (June, 2011)
   http://www.aabio.com.au/crayfish.html
9. Identification and Ecology of Australian Freshwater Invertebrates (June, 2011)
   http://www.mdfrc.org.au/bugguide/index.htm
10. Campbell, A. and Dawes, J. (2004) Encyclopedia of Underwater Life. Oxford University Press, Oxford.