Chelodina expansa
| Broad-shelled long-necked turtle | |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Sauropsida |
| Order: | Testudines |
| Suborder: | Pleurodira |
| Family: | Chelidae |
| Subfamily: | Chelodininae |
| Genus: | Chelodina |
| Subgenus: | Macrochelodina |
| Species: | C. (M.) expansa |
| Binomial name | |
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Chelodina expansa (Gray, 1857) |
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| Synonyms | |
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Chelodina (Macrochelodina) Expansa, commonly known as the broad-shelled river turtle or the broad-shelled snake-necked turtle , is a pleurodire freshwater turtle and is the biggest of the long-necked turtles. The broad-shelled river turtle is one of the oldest maturing and longest living species of freshwater turtles in existence and occurs in wide sympatry with Emydura macquarii and Chelodina longicollis. C. expansa is listed as ‘vulnerable’ in South Australia and ‘threatened’ in Victoria.
Broad-shelled river turtles are found throughout the Murray-Darling River system of South-Eastern Australia. A number of distinctive populations have been located across central and coastal Queensland areas.
C. expansa is mostly found in turbid waters at depths of which are greater than three metres. The turtle generally inhabits permanent streams and may occur in rivers, oxbows, ponds in floodplains, backwater, and swamps across its distributed region, however is mostly a river turtle. The broad-shelled river turtle will tend to inhabit environments that are undisturbed and have moderate vegetation cover for nest construction. The turtle has shown a preference of aquatic habitats in structured environments, where submerged logs, root systems and dead trees occur. Factors such as shelter from predators, and food availability may influence the habitat preference of e. Expansa. Seasonal changes including the water levels and flow may also influence the selected the habitat.
The broad-shelled river turtle has a broad, oval and flattened shell with a length of around 50cm. The carapace length is often longer in females then males. The turtle has a rich brown to blackish-brown above, typically displaying fine dark flecks or reticulations. The turtle has a whitish or creamy coloured underneath. The plastron is narrow and the shell does not display any noticeable expansion anteriorly. The shell is usually twice as long as wide and is broadest at the level of the bridge. The head is broad and highly depressed and the eyes are directly dorsolateral. When extended, the neck may surpass the measurement of the carapace.
The broad-shelled river turtle is mostly active from the Australian spring season (October) through to early autumn (April). The species tends to decrease in movement and feeding over the cooler winter months.C. expansa is described to also show head bobbing and self-grooming actions.
Chelodina expansa spends most of its time in water. During periods when water levels are low, C. expansa will traverse over land to find other water sources. The turtle may also bury itself into mud and enter extended periods of aestivation until rain occurs and water levels increase. The broad-shelled river turtle has shown a ‘body-slamming’ type behaviour when compacting nests The turtle is not typically found to nest after dark and is generally observed to nest during daylight. This is assumed to be a strategy to select more thermally appropriate nest sites, where both areas of sun and shade exposure can be identified. They will tend to select sites that have higher sun coverage to construct their nests. Due to the extended incubation period, the selection of nest sites is commonly a long way from the waters edge and is seen to be a behavioural strategy to minimise the risk of nest flooding. Hatchlings are however exposed to a number of challenges during their travels to the water.
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Wikipedia