Flecker's spiny crayfish (Euastacus fleckeri)

Description

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Flecker's spiny crayfish fact file

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

Flecker’s spiny crayfish (Euastacus fleckeri) is a large freshwater crayfish found only in Queensland, Australia ^{(1) (3) (4) (5)}. It is a particularly large Euastacus species ⁽²⁾, with a blue to brown body and bright red tips to its large, pincer-like claws ⁽⁶⁾.

Like other Euastacus species, Flecker’s spiny crayfish is characterised by its spiny appearance ^{(2) (4) (5)}. However, it is considered to be quite distinct from most other members of the genus ^{(2) (4)}, and the spines on its abdomen are somewhat reduced ^{(4) (5)}.

As in other crayfish, the abdomen of Flecker’s spiny crayfish is divided into six segments, and ends in a tail fin composed of a central tail flap (telson) and surrounding flaps called uropods. In addition to the large claws, crayfish have four more pairs of appendages attached to the thorax. These are known as ‘pereiopods’ and are modified for feeding and walking. The abdomen bears further appendages, which are known as ‘pleopods’ or ‘swimmerets’ and are involved in swimming and in the brooding of eggs by the female ^{(7) (8)}.

On its head, a crayfish has a pair of compound eyes, as well as several feeding appendages, a pair of antennae and a second pair of smaller, central antennae known as ‘antennules’. The body of a crayfish is encased in a hard, protective carapace ^{(7) (8)}. In Flecker’s spiny crayfish, the front part of the carapace which projects in front of the eyes (the ‘rostrum’) is quite short, broad and U-shaped ^{(4) (5)}.

Also known as

Flecker’s crayfish.

Size

Occipital carapace length: up to 11.9 cm ⁽²⁾

Flecker's spiny crayfish biology

Little specific information is available on the biology of Flecker’s spiny crayfish. However, like other freshwater crayfish it builds burrows around the streams it inhabits ⁽⁷⁾, usually under rocks or logs ^{(1) (3)}. The diet is likely to include a variety of plant and animal matter, as well as detritus ⁽⁷⁾.

Freshwater crayfish do not have long, planktonic larval stages, instead producing large eggs which hatch into miniature versions of the adult. The eggs are incubated on the pleopods of the female before hatching ^{(7) (8)}. The female Flecker’s spiny crayfish reaches maturity at an occipital carapace length of about four to six centimetres ⁽²⁾.

Flecker's spiny crayfish range

Flecker’s spiny crayfish is endemic to northern Queensland, Australia, where it occurs in a small highland area west of Mossman, on Mount Lewis, Mount Spurgeon, and in areas in between ^{(1) (3) (4) (5)}. The distribution of this species is highly fragmented ^{(1) (3)}.

Flecker's spiny crayfish habitat

This freshwater species inhabits cool, clear, fast-flowing headwater streams in rainforest ^{(1) (2) (3)}, at elevations above 900 metres ^{(1) (3) (4) (5)}. Like most other Euastacus species, Flecker’s spiny crayfish prefers well-oxygenated, shaded locations ^{(1) (3)}.

Flecker's spiny crayfish status

Flecker’s spiny crayfish is classified as Endangered (EN) on the IUCN Red List ⁽¹⁾.

Flecker's spiny crayfish threats

Although Flecker’s spiny crayfish is thought to be relatively common within its range, it has a rather restricted and severely fragmented distribution. It also has quite specialised habitat requirements, and any decline in the extent or quality of its habitat will therefore significantly affect its populations ⁽¹⁾. The slow reproductive rate of Flecker’s spiny crayfish makes it harder for the species to recover from any declines ⁽¹⁾.

One of the main threats to Flecker’s spiny crayfish is the loss and degradation of its habitat, due to the destruction of streamside vegetation, rooting by feral pigs ^{(1) (3)}, and agricultural activities, which can reduce water quality through factors such as siltation ⁽³⁾. Climate change is also a potentially significant threat, as it may lead to increased temperatures, altered water regimes, more severe weather events, more frequent bushfires, and the loss of cool highland forest habitats ^{(1) (3)}.

In addition to the threats to its habitat, Flecker’s spiny crayfish may be under threat from introduced species such as cats and foxes. It may also be affected by the non-native cane toad (Bufo marinus), although the exact impact of this species is not yet known ^{(1) (3)}. Although there is a catch size limit for spiny crayfish of over nine centimetres occipital carapace length, meaning that individuals below this should not be caught, Flecker’s spiny crayfish is a particularly large species that often exceeds this size. It may therefore be at risk of over-exploitation by recreational fishing ^{(1) (3)}.

Flecker's spiny crayfish conservation

There are no specific conservation measures currently in place for Flecker’s spiny crayfish ^{(1) (3)}. However, its range coincides with the Northern Queensland World Heritage Area, which may offer this species some protection ^{(1) (3)}.

Further research is needed into the threats to Flecker’s spiny crayfish, as well as into its populations, biology, habitat requirements, and the effects of illegal recreational fishing ^{(1) (3)}. In Queensland, all Euastacus crayfish are officially ‘no take’ species under the Fisheries Act 1994 and should be released if captured. However, illegal poaching does occur, and this species may also be confused with unprotected Cherax species and so taken by mistake ^{(1) (3)}.

In 2005, a project was started with the aim of surveying, identifying and documenting all of Australia’s freshwater crayfish species, including Flecker’s spiny crayfish. It is hoped that the information gathered by the Australian Crayfish Project (ACP) will help in the conservation of freshwater crayfish species and their habitats ⁽⁹⁾.

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.

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. 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
4. 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.
5. Riek, E.F. (1951) The freshwater crayfish (family Parastacidae) of Queensland. Records of the Australian Museum, 22(4): 368-388.
6. SpinyCrayfish.com: Euastacus fleckeri - Flecker’s Spiny Crayfish (June, 2011)
   http://www.spinycrayfish.com/?page_id=1022
7. Identification and Ecology of Australian Freshwater Invertebrates (June, 2011)
   http://www.mdfrc.org.au/bugguide/index.htm
8. Campbell, A. and Dawes, J. (2004) Encyclopedia of Underwater Life. Oxford University Press, Oxford.
9. Australian Aquatic Biological Pty Limited - Australian Crayfish Project (June, 2011)
   http://www.aabio.com.au/crayfish.html