Mount Glorious spiny crayfish (Euastacus setosus)

Description

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Mount Glorious spiny crayfish fact file

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

The Mount Glorious spiny crayfish (Euastacus setosus) 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 Mount Glorious spiny crayfish has greatly reduced spines and, along with other less spiny species in the genus, it has been grouped into a distinctive complex 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.

Mount Glorious spiny crayfish biology

Very little specific information is available about the biology of the Mount Glorious spiny crayfish.

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 ^{(4) (5)}. Most crayfish are nocturnal, remaining in burrows during the day, or under stones and logs ⁽⁵⁾.

Breeding typically occurs in the autumn in 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 ⁽⁴⁾. 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 ^{(4) (5)}.

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 ⁽⁶⁾.

Mount Glorious spiny crayfish range

The Mount Glorious spiny crayfish is endemic to Australia. It is known only from the headwater tributaries of the Pine River, near Mount Glorious, Brisbane, where it occurs in a small number of sites at elevations above 500 metres ^{(1) (2)}.

It is possible that the Mount Glorious spiny crayfish occurs elsewhere in the surrounding D'Aguilar Range, although extensive clearing of rainforest in the area means that suitable remaining habitat for this species is limited ^{(1) (2)}.

Mount Glorious spiny crayfish habitat

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

Mount Glorious spiny crayfish status

The Mount Glorious spiny crayfish is classified as Critically Endangered (CR) on the IUCN Red List ⁽¹⁾.

Mount Glorious spiny crayfish threats

The Mount Glorious spiny 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. 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)}.

Climate change is also likely to pose a major threat to the Mount Glorious spiny crayfish ^{(1) (2) (7)}, 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, it 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)}.

The Mount Glorious spiny crayfish may also be confused with several other crayfish in the genus Cherax, and may therefore be accidentally taken by recreational fishers ^{(1) (2)}.

Mount Glorious spiny crayfish conservation

The range of the Mount Glorious spiny crayfish coincides with Maiala National Park, which may afford this species some level of protection. However, there are currently no specific conservation measures targeted at the Mount Glorious spiny 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 Mount Glorious spiny 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⁾.

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.

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.

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. Campbell, A. and Dawes, J. (2004) Encyclopedia of Underwater Life. Oxford University Press, Oxford.
5. Burton, M. and Burton, R. (2002) The International Wildlife Encyclopedia, Volume 10. Benchmark Books, Glasgow.
6. Breithaupt, T. and Thiel, M. (2010) Chemical Communication in Crustaceans. Springer, Berlin.
7. 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