Maleny hairy crayfish (Euastacus urospinosus)

Description

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Maleny hairy crayfish fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
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Maleny hairy crayfish description

The Maleny hairy crayfish (Euastacus urospinosus) is a highly threatened crayfish of the Euastacus genus, which is the largest of the ten Australian crayfish genera and includes some of the largest and rarest species of crayfish in the world ⁽²⁾. 

Often broadly referred to as the ‘spiny crayfish’, many species in the genus Euastacus are armed with prominent and well-developed spines. However, the Maleny hairy crayfish has greatly reduced spines and, along with other less spiny species in the genus, it has been grouped into a distinctive complex of species from south-east Queensland, known as the setosus complex ⁽³⁾.

Like other crayfish, this large, freshwater species has a carapace that protects the head and internal organs. The six segments of the abdomen are individually encased, with a flexible membrane between them to allow movement. Crayfish also have a pair of large fore-claws, followed by four pairs of walking legs and then four pairs of small swimming legs, called ‘swimmerets’. These swimmerets are covered with fine hairs, to which the female attaches her eggs. A central tail flap is surrounded by four other flaps that are used to move the crayfish rapidly through the water, as well as curling up to form a brood chamber. The eyes are each borne on an eyestalk, while a pair of large feelers (or antennae) and a pair of small, fine, centrally-located feelers (or antennules) make the crayfish’s sense of touch and taste particularly sensitive.

Maleny hairy crayfish biology

Very little specific information is available on the biology of the Maleny hairy crayfish. It is thought to be very slow to mature compared with many other crayfish species, with females taking up to six years before breeding for the first time ⁽⁵⁾.

In general, freshwater crayfish have strong jaws and two pairs of secondary jaws, called maxillae, which allow them to consume a wide variety of both plant and animal matter ^{(6) (7)}. Most crayfish are nocturnal, spending the day in burrows which have been excavated in the banks of streams, or under stones and logs ^{(5) (7)}.  

Breeding typically occurs in the autumn for most Euastacus species, when the male transfers sperm to the female to fertilise the eggs. In some species the first pair of appendages on the abdomen has grooves, along which the sperm flows, although the sperm may also be transferred to the female as a spermatophore ⁽⁶⁾. The female typically lays a large clutch of eggs which are attached to the bristles on the swimmerets, where they remain for the whole incubation period. Unusually among crustaceans, crayfish do not have a larval stage ^{(6) (7)}.

Chemical signals are thought to play an important role in the crayfish life cycle, and may have a role in courtship, brood care and aggressive interactions between individuals. Aggression is a common crayfish social behaviour which establishes a dominance hierarchy, with more dominant individuals gaining better access to shelter, food and mating partners ⁽⁸⁾.

Maleny hairy crayfish range

Endemic to Australia, the Maleny hairy crayfish has a fragmented distribution, occurring intwo geographically separate areas which are around 15 kilometres apart ^{(1) (2)}.

It is restricted to a tributary of the Obi Obi Creek in Queensland, between Maleny and Mapleton in the Blackall Ranges, as well as a small number of other sites in the Conondale Ranges ^{(1) (2) (4) (5)}.

Maleny hairy crayfish habitat

A freshwater crayfish, the Maleny hairy crayfish inhabits the cool waters close to the source of creeks and streams in areas of rainforest, at elevations greater than 240 metres. Like other species of Euastacus, this species prefers heavily shaded, well-oxygenated waters, where it can burrow under logs and rocks ^{(1) (2)}.

Maleny hairy crayfish status

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

Maleny hairy crayfish threats

The Maleny hairy crayfish is a particularly vulnerable species due to its extremely restricted range. Localised threats, such as bush fires, poor forest management practices, habitat destruction and over-exploitation by collectors are all known to negatively impact this species’ population. Disturbance to stream banks and burrows, water pollution and urban development are also important threats to this species ⁽⁵⁾.

Additionally, introduced species such as the cane toad (Bufo marinus), as well as cats, foxes, pigs and goats, have all been found to affect crayfish populations ^{(1) (2)}. Feral pigs in particular are known to affect the Maleny hairy crayfish, by rooting and destroying burrows throughout its range ⁽⁴⁾. 

Climate change is also likely to pose a major threat to the Maleny hairy crayfish ^{(1) (2) (9)}, with increasing temperatures, decreased rainfall, which will alter hydrological regimes, severe weather events and loss of suitable highland habitat all likely to impact heavily on this threatened freshwater crayfish. This species has a limited thermal tolerance and, consequently, is restricted to cool headwater streams in forested catchment areas. Therefore, increasing temperatures are likely to result in further range contraction of this species ^{(1) (2)}.

Illegal recreational fishing is a further danger to the Maleny hairy crayfish ⁽²⁾, and this species may also be confused with several other crayfish in the genus Cherax, and so may also be accidentally taken by fishers ^{(1) (2)}.

Maleny hairy crayfish conservation

The Maleny hairy crayfish occurs within the Conondale and Mapleton Falls National Parks, which may afford this species some level of protection ^{(1) (2)}. However, there are currently no specific conservation measures targeted at the Maleny hairy crayfish ⁽¹⁾. All species in the Euastacus genus are designated as ‘no take’ species in Queensland under the Fisheries Act 1994, and must be released if captured ^{(1) (2)}.

There is an urgent requirement to carry out further research on the Maleny hairy crayfish, which will greatly aid any future conservation or management initiatives for the species. Information on its biology, life history, population size, habitat requirements, thermal tolerances and resilience to exotic species are particularly required ⁽²⁾. This species would also benefit from protection of its habitat and monitoring of the water quality in areas where it occurs ⁽⁵⁾.

Find out more

Find out more about Australian crayfish:

• The 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.

Antennae

Pair of sensory structures on the head of invertebrates.

Carapace

The top shell of a turtle or tortoise. In arthropods (insects, crabs etc), the fused head and thorax (the part of the body located near the head), also known as the ‘cephalothorax’.

Crustaceans

Diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.

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.

Fertilisation

The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.

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.

Maxillae

In vertebrates, the maxilla is the posterior bone of the upper jaw. In certain arthropods, the maxillae are paired structures that act as mouthparts.

Nocturnal

Active at night.

Spermatophore

Gelatinous jelly cone with a sperm cap deposited by a male during courtship and picked up by the cloacal lips of the female.

Thorax

Part of the body located near the head in animals. In insects, the three segments between the head and the abdomen, each of which has a pair of legs. In vertebrates the thorax contains the heart and the lungs.

References

1. IUCN Red List (June, 2011)
   http://www.iucnredlist.org/
2. Coughran, J. and Furse, J.M. (2010) An assessment of genus Euastacus (49 species) versus IUCN Red List criteria. Report prepared for the global species conservation assessment of lobsters and freshwater crayfish for the IUCN Red List of Threatened Species. The Environmental Futures Centre, Griffith School of Environment, Griffith University, Gold Coast Campus, Queensland.
3. Coughran, J. (2008) Distinct groups in the genus Euastascus? Freshwater Crayfish, 16: 123-130.
4. Department of Natural Resources, Department of Environment and Environment Australia. (1997) Systematic Vertebrate Fauna Survey Project. Stage II – Assessment of Habitat Quality for Priority Specie in Southeast Queensland Bioregion. Queensland CRA/RFA Steering Committee, Queensland, Australia. Available at:
   http://www.daff.gov.au/__data/assets/pdf_file/0008/49589/qld_se_eh2b.pdf
5. Mary Cairncross Scenic Reserve - Euastacus urospinosus (June, 2011)
   http://www.mary-cairncross.com.au/mountain-freshwater-crayfish.php
6. Campbell, A. and Dawes, J. (2004) Encyclopedia of Underwater Life. Oxford University Press, Oxford.
7. Burton, M. and Burton, R. (2002) The International Wildlife Encyclopedia, Volume 10. Benchmark Books, Glasgow.
8. Breithaupt, T. and Thiel, M. (2010) Chemical Communication in Crustaceans. Springer, Berlin.
9. Low, T. (2007) Climate change and Brisbane Biodiversity: A Critique of the Climate Change & Energy Taskforce Final Report, with Recommendations for Biodiversity added. A report for the Brisbane City Council. Available at:
   http://www.brisbane.qld.gov.au/documents/environment/tim_low%27s_report_on_biodiversity.pdf