Narrow-breasted snake-necked turtle (Chelodina oblonga)

Description

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Narrow-breasted snake-necked turtle fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
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Narrow-breasted snake-necked turtle description

A peculiar reptile, the narrow-breasted snake-necked turtle (Chelodina oblonga) has a remarkably long neck, which in some cases may be even longer than its body ^{(2) (3) (4) (5) (6)}. The narrow-breasted snake-necked turtle is part of a group of species collectively known as ‘side-necked turtles’ due to the characteristic manner in which the neck is retracted sideways in front of the shell, leaving the head and neck relatively exposed. Some species within this group, including the narrow-breasted snake-necked turtle, are more commonly known as ‘snake-necked turtles’ due to the mobility and snake-like appearance of their long necks ^{(4) (7)}.

Also known as the oblong turtle, the narrow-breasted snake-necked turtle has a narrow, oblong or oval-shaped shell, or carapace ^{(2) (5)}. The length of the carapace is more than twice its width ⁽⁴⁾, and horny scutes overlie the bony shell ⁽⁸⁾.

The carapace varies in colour from light brown or olive-brown to blue-grey or black, sometimes with dark flecking on the lighter areas ^{(2) (5)}. The underside, or plastron, of the narrow-breasted snake-necked turtle is also variable in colouration. It is usually creamy or yellowish ^{(2) (5)}, but it may sometimes be brown, with dark brown or black regularly patterned markings ⁽⁵⁾. The skin of the narrow-breasted snake-necked turtle is covered in tubercles and is typically olive-grey on the upperparts, often with dark mottling, while the skin on the underparts is usually pale grey. The skin on the back of the neck and mouth may be creamy-yellow to white ^{(2) (5)}.

The streamlined, elongated head of the narrow-breasted snake-necked turtle is somewhat flattened ^{(2) (5) (6) (9)}, the snout protrudes forwards slightly and barbels are present on the chin ^{(2) (5)}. All of this species’ limbs have distinct ankle joints rather than being paddle-shaped ⁽⁴⁾, and the feet are webbed ⁽⁹⁾, with four claws on each foot ^{(4) (8)}.

The female narrow-breasted snake-necked turtle is generally larger than the male ⁽⁸⁾. The male has a more concave plastron in comparison to the female and also has a longer, thicker tail ^{(2) (5)}.

The juvenile narrow-breasted snake-necked turtle has a pear-shaped carapace ⁽⁵⁾. It also differs from the adult in its colouration ^{(4) (8)}, with the carapace tending to be either grey or brown with dark markings and a yellow rim to the outer edge of the scutes ⁽⁵⁾. The skin on the upperparts is grey, except for the head which may have a slightly yellowish tinge. The plastron of the juvenile is black or steel grey, while the skin on the underparts is yellow ⁽⁵⁾.

Also known as

Oblong turtle, Southwestern long-necked turtle.

Synonyms

Chelodina colliei, Macrodiremys oblonga.

Size

Carapace length: up to 40 cm ⁽²⁾

Narrow-breasted snake-necked turtle biology

The narrow-breasted snake-necked turtle is carnivorous ^{(5) (7) (11)}, with its diet consisting of aquatic insects, small fish, shrimp and other small crustaceans, tadpoles and frogs. This species also consumes carrion. Hatchling narrow-breasted snake-necked turtles are known to feed on aquatic plants ^{(5) (11)}.

To capture its prey, the narrow-breasted snake-necked turtle retracts its head and neck towards the body, holding them there until unsuspecting prey ventures within striking range. The narrow-breasted snake-necked turtle has an exceptionally fast strike, which is the fastest of all the Chelodina species. Once the narrow-breasted snake-necked turtle has detected its prey, it is able to shoot its head forward in a striking motion with incredible speed, allowing it to catch even fast-moving prey species ^{(2) (5) (6) (8)}.

Like other reptiles, the narrow-breasted snake-necked turtle is cold blooded and controls its body temperature through a process called thermoregulation. After eating, the narrow-breasted snake-necked turtle can increase the speed and effectiveness of its digestion by basking to increase its body temperature. This species may bask out of the water, on a bank or on woody debris protruding from the water, although it will often float in the warmer surface layer of the water with its limbs spread, slowly paddling with just its head and shell visible ⁽⁵⁾.

Mating in the narrow-breasted snake-necked turtle occurs during winter and spring ⁽⁵⁾, with most females nesting in spring and mid-summer, between September and January ^{(5) (9) (14)}. The female leaves the water to lay its eggs ^{(2) (5) (10)}, with nests sometimes found as far as 500 metres from the water’s edge ⁽⁵⁾. Nest sites are usually located in relatively bare areas, free from dense vegetation ^{(2) (5)}. The female narrow-breasted snake-necked turtle will pick a suitable nesting site and dig a hole in which to lay its eggs, which are then buried ⁽¹⁰⁾. The female uses its shell to pat down the earth of the nest site ^{(5) (10)}, an action known as ‘tamping’ ^{(8) (10)}.

The female narrow-breasted snake-necked turtle can lay up to three clutches a year, with each clutch usually containing between 8 and 16 elongated white eggs ^{(2) (5)}. The incubation period lasts between 183 and 222 days ⁽²⁾, although the exact timing of hatching is determined by weather conditions ^{(2) (10)}. Once the eggs have been buried, the female returns to the water and no further parental care is given to the eggs or hatchlings ⁽¹⁰⁾.

The male narrow-breasted snake-necked turtle becomes sexually mature at a carapace length of approximately 14 centimetres, while the female usually reaches maturity at a carapace length of between 16 and 21 centimetres ^{(2) (5)}. For both the male and female narrow-breasted snake-necked turtle this usually occurs between 7 and 12 years of age ⁽¹⁰⁾.

Narrow-breasted snake-necked turtle range

The narrow-breasted snake-necked turtle is native to Australia ⁽¹⁾. It is found only in the southwest of Western Australia ^{(4) (5)}.

Narrow-breasted snake-necked turtle habitat

A semi-aquatic species ^{(2) (9)}, the narrow-breasted snake-necked turtle resides in swamps, streams, lakes, lagoons and other permanent bodies of water ^{(1) (2) (5)}.

Although primarily a freshwater species ^{(1) (4) (5) (8) (10)}, the narrow-breasted snake-necked turtle can tolerate brackish and even saline waters, though only for short periods of time ⁽⁵⁾.

Narrow-breasted snake-necked turtle status

The narrow-breasted snake-necked turtle is classified as Near Threatened (NT) on the IUCN Red List ⁽¹⁾.

Narrow-breasted snake-necked turtle threats

Introduced and invasive species are a major threat to the narrow-breasted snake-necked turtle, with species such the red fox (Vulpes vulpes) known to consume eggs and adult turtles ⁽⁵⁾. The expanding range of non-native species of crayfish poses a threat to the young of both the narrow-breasted snake-necked turtle and other Australian freshwater turtles, with hatchlings of the narrow-breasted snake-necked turtle being particularly vulnerable to predation by crayfish species of the Cherax genus ^{(5) (12)}.

Other threats to the narrow-breasted snake-necked turtle include habitat loss and habitat degradation, largely due to the draining or filling of aquatic habitats for agricultural use. Roads encroaching on the narrow-breasted snake-necked turtle’s habitat may also cause a severe problem, particularly as it may prevent this species from being able to access its nesting grounds. The fragmentation of this species’ habitat has resulted in the deaths of many female narrow-breasted snake-necked turtles as they attempt to find a suitable place to nest ⁽⁵⁾.

Narrow-breasted snake-necked turtle conservation

There are currently no known conservation measures specifically targeted at the narrow-breasted snake-necked turtle.

Find out more

Find out more about the narrow-breasted snake-necked turtle:

Ernst, C.H., Altenburg, R.G.M. and Barbour, R.W. (1997) Turtles of the World - Chelodina oblongata. ETI Information Systems Ltd., Netherlands. Available at:
http://wbd.etibioinformatics.nl/bis/turtles.php?selected=beschrijving&menuentry=soorten&id=150

Find out more about tortoise and freshwater turtle conservation:

• IUCN/SSC Tortoise and Freshwater Specialist Group:
  http://www.iucn-tftsg.org/

Find out more about reptile conservation:

• International Reptile Conservation Foundation:
  http://www.ircf.org/

Authentication

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Glossary

Barbels

Fleshy projections near the mouth of some aquatic vertebrates.

Brackish

Slightly salty water, usually a mixture of salt and freshwater, such as that found in estuaries.

Carapace

The top shell of a turtle or tortoise.

Carnivorous

Feeding on flesh.

Carrion

The flesh of a dead animal.

Crustaceans

Diverse group of animals with jointed limbs and a hard external skeleton, 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.

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.

Plastron

The lower shell of a turtle or tortoise.

Scute

A large scale on the shell of a turtle or tortoise.

Thermoregulate

To control the body temperature.

Tubercle

A small, rounded, wart-like bump on the skin or on a bone.

References

1. IUCN Red List (April, 2012)
   http://www.iucnredlist.org/
2. Ernst, C.H., Altenburg, R.G.M. and Barbour, R.W. (1997) Turtles of the World - Chelodina oblongata. ETI Information Systems Ltd., Netherlands. Available at:
   http://wbd.etibioinformatics.nl/bis/turtles.php?selected=beschrijving&menuentry=soorten&id=150
3. Burbidge, A.A. and Kuchling, G. (2004) Western Swamp Tortoise (Pseudemydura umbrina) Recovery Plan. Department of Conservation and Land Management, Western Australia. Available at:
   http://www.environment.gov.au/biodiversity/threatened/publications/recovery/p-umbrina/pubs/p-umbrina.pdf
4. Georges, A. and Thomson, S. (2010) Diversity of Australasian freshwater turtles, with an annotated synonymy and keys to species. Zootaxa, 2496: 1-37.
5. Carettochelys.com - Oblong turtle (Chelodina oblonga) (April, 2012)
   http://www.carettochelys.com/chelodina/chelodina_oblonga_1.htm
6. Thomson, S. (2003) Long Necks, Flat Heads and the Evolution of Piscivory. World Chelonian Trust, Vacaville, California, and the Applied Ecology Research Group and CRC for Freshwater Ecology, University of Canberra, Australia. Available at:
   http://www.chelonia.org/articles/longneck_flathead_evolution.htm
7. Halliday, T. and Alder, K. (2002) The New Encyclopedia of Reptiles and Amphibians. Oxford University Press, Oxford.
8. Legler, J.M. and Georges, A. (1993) Family Chelidae. In: Glasby, C.G., Ross, G.J.B. and Beesley, P.L. (Eds.) Fauna of Australia. Volume 2A, Amphibia and Reptilia. Available at:
   http://iae.canberra.edu.au/reprints/1993_Legler_Georges_Chelidae.pdf
9. Ernst, C.H., Altenburg, R.G.M. and Barbour, R.W. (1997) Turtles of the World - Family Chelidae (Side-necked Turtles). ETI Information Systems Ltd., Netherlands. Available at:
   http://wbd.etibioinformatics.nl/bis/turtles.php?selected=beschrijving&menuentry=soorten&id=14
10. Georges, A., Limpus, C.J. and Parmenter C.J. (1993) Natural history of the Chelonia. In: Glasby, C.G., Ross, G.J.B. and Beesley, P.L. (Eds.) Fauna of Australia. Volume 2A, Amphibia and Reptilia. Available at: 
    http://www.environment.gov.au/biodiversity/abrs/publications/fauna-of-australia/pubs/volume2a/17-fauna-2a-chelonia-naturalhistory.pdf
11. Lewis, E., Baudains, C. and Mansfield, C. (2009) Engaging students in science: turtle nestwatch. Teaching Science, 55(1): 50-53. Available at:
    http://researchrepository.murdoch.edu.au/1595/1/Turtle_nestwatch.pdf
12. Bradsell, P., Prince, J., Kuchling, G. and Knott, B. (2002) Aggressive interactions between freshwater turtle, Chelodina oblonga, hatchlings and freshwater crayfish, Cherax spp.: implications for the conservation of the critically endangered western swamp turtle, Pseudemydura umbrina. Wildlife Research, 29(3): 295-301.