Mistake Mountains crayfish (Euastacus jagara)

Description

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Mistake Mountains crayfish fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
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Mistake Mountains crayfish description

A highly threatened crayfish, the Mistake Mountains crayfish (Euastacus jagara) belongs to the largest of the ten Australian crayfish genera. Species in the genus Euastacus, which includes some of the largest and rarest species of crayfish in the world, are often broadly referred to as the ‘spiny crayfish’ ⁽²⁾.

Compared with many other species in the genus, which typically possess an impressive array of spines on the thorax, abdomen and claws ⁽²⁾, the Mistake Mountains crayfish is poorly spinose. There are between three and six large spines, as well as additional smaller spines, on the large, pincer-like claws, but the spines on the abdomen are minimally developed. It also has a dense covering of bristles all over the body ⁽³⁾.

The Mistake Mountains crayfish is dark green or green-blue to orange-brown on the back, with a bluish tint to the underparts and the sides. The legs are light blue or blue-brown. The claws have a distinctive mottled pattern, with a greenish tint highlighted with a brighter blue, and the large spines are generally red, with yellow tips ⁽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.

Mistake Mountains crayfish biology

The Mistake Mountains crayfish constructs an intricate burrow in the stream bed, stream bank, or in the adjacent forest floor, sometimes up to two metres from the water. Often a deep and complex structure, the burrow typically contains five or more entrances, as well as numerous chambers. Crayfish are mainly active during the day, with a peak in activity just after sunset ⁽³⁾.

Very little is known about the diet of the Mistake Mountains crayfish⁽³⁾, although most crayfish are typically omnivorous ⁽⁴⁾. It is likely that fruits make up a large proportion of the Mistake Mountains crayfish’s diet, and are probably collected and transported back to the burrow ⁽³⁾.

Male and female Mistake Mountains crayfish become active in the streams during autumn, marking the onset of the breeding season. Females have been observed carrying clutches of 50 to 70 yellowish-brown eggs attached to the swimmerets on the underside of the body, and the eggs develop throughout the winter. Juveniles become independent the following summer ⁽³⁾.

Mistake Mountains crayfish range

Endemic to Australia, the Mistake Mountains crayfish is known only from a few sites in a small area of the Mistake Mountains, south-east Queensland ^{(1) (2)}. 

Originally described from a single site in Flaggy Creek (a highland tributary of the Brisbane River), the Mistake Mountains crayfish has since been collected at several other sites, including Shady Creek, which is an upper tributary of Blackfellow Creek, as well as three branches of Dalrymple Creek ⁽³⁾.

Mistake Mountains crayfish habitat

Restricted to highland headwater streams at elevations of 714 to 1,208 metres, the Mistake Mountains crayfish is typically found in areas which are well shaded by rainforest canopy ^{(1) (3)}.

The Mistake Mountains crayfish inhabits all sections of the streams, which usually have a rocky or gravelly bottom, including both pools and riffles. Rainforest spinach (Elatostema reticulatum) is common along the steam margin, and the water often contains abundant woody debris and leaf litter ⁽³⁾.  

Mistake Mountains crayfish status

The Mistake Mountains crayfish is classified as Critically Endangered (CR) on the IUCN Red List ⁽¹⁾.

Mistake Mountains crayfish threats

The Mistake Mountains 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 may all have a significant negative effect on this species’ population. Additionally introduced species, such as the cane toad (Bufo marinus), cats, foxes, pigs and goats, have all been found to impact on crayfish populations ^{(1) (2) (3)}.

Climate change is also likely to pose a major threat to the Mistake Mountains crayfish, 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 particularly narrow thermal tolerance and a small, fragmented range, being restricted to cool headwater streams above elevations of 700 metres. Increasing temperatures are likely to result in further range contraction of this species ^{(1) (2) (3)}.

The Mistake Mountains crayfish may also be confused with several other crayfish in the genus Cherax, and may therefore be accidentally taken by recreational fishers ⁽³⁾.

Mistake Mountains crayfish conservation

The Mistake Mountains crayfish’s range falls entirely within the bounds of the Mount Mistake National Park, which may afford this species some level of protection. However, there are currently no specific conservation measures targeted at the Mistake Mountains crayfish ^{(1) (3)}. 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) (3)}.

There is an urgent requirement to carry out further research on the Mistake Mountains crayfish, which will greatly facilitate any future conservation or management initiatives for this species. Information on its biology, life history, population size, habitat requirements, thermal tolerances and resilience to exotic species are particularly required ^{(2) (3)}.

Find out more

Find out more about the Mistake Mountains crayfish:

• McCormack, R.B., Coughran, J., Furse, J.M. and Van der Werf, P. (2010) Conservation of imperiled crayfish - Euastacus jagara (Decapoda: Parastacidae), a highland crayfish from the Main Range, South-Eastern Queensland, Australia. Journal of Crustacean Biology, 30(3): 531-535.

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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’.

Endemic

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

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.

Omnivorous

Feeding on both plants and animals.

Riffles

Light rapids where water flows across a shallow section of river.

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. McCormack, R.B., Coughran, J., Furse, J.M. and Van der Werf, P. (2010) Conservation of imperiled crayfish - Euastacus jagara (Decapoda: Parastacidae), a highland crayfish from the Main Range, South-Eastern Queensland, Australia. Journal of Crustacean Biology, 30(3): 531-535.
4. Campbell, A. and Dawes, J. (2004) Encyclopedia of Underwater Life. Oxford University Press, Oxford.