- Other Geographic Terms
- island endemic
Common snake-necked turtles are semi-aquatic. Although they prefer the slow moving waters of swamps or wetlands, they can also be found in streams and rivers. In aquatic environments, they are primarily bottom dwelling, but occasionally leave the water to bask in the sun. If conditions are dry, they seek out new habitat. Some individuals seek extended refuge and may estivate until flood waters return. Estivation usually occurs under trees in forested habitats where they can burrow into fallen foliage on the forest floor near shrubs and logs. Common snake-necked turtles are usually the only turtle species in their immediate environment. ("Australo-American sideneck turtles", 2003; Kennett, et al., 2009; Roe and Georges, 2008a)
- Terrestrial Biomes
- Aquatic Biomes
- lakes and ponds
- rivers and streams
- temporary pools
Common snake-necked turtles are medium-sized turtles, with an average length of 25 cm. They have a black to light brown oval carapace that contains a shallow central groove. The plastron is cream colored with dark seams. Their necks are long and narrow, with a brown to gray dorsal surface and a yellow ventral surface. On average, the neck is approximately 60% of the plastron length and is covered with short tubercles. The head is small and pointed and the limbs are dark grey to brown. Sexual dimorphism in this species is subtle. When compared to males, females are larger, have deeper shells and have a shorter, fatter tail that is hidden. Males have longer, thicker tails than females and a concave plastron. These distinctions are subtle which makes gender determination difficult. Juveniles tend to be black to dark gray with an orange stripe down either side of the neck and jaw. They also have orange spots on the plastron. ("Australo-American sideneck turtles", 2003; Ernst and Barbour, 1989; Kennett, et al., 2009)
- Sexual Dimorphism
- female larger
- sexes shaped differently
- Range mass
- 444 to 816 g
- 15.65 to 28.76 oz
- Average mass
- 602 g
- 21.22 oz
- Average length
- 25 cm
- 9.84 in
- Mating System
- polygynandrous (promiscuous)
Common snake-necked turtles breed once annually, from September to October. Nesting occurs during late spring and early summer, from October to December. Females lay 8 to 24 hard-shelled, ellipsoid eggs in nests close to water. Eggs are approximately 20 mm wide and 30 mm long and weigh between 6 and 7 g. Typically, females lay three clutches per year are all eggs are laid. Embryo estivation occurs during development, with incubation lasting between 120 to 150 days. Young emerge during autumn, from January to late April. Common snake-necked turtles are slow to mature, and most males reach sexual maturity between 7 and 8 years of age. Females reach sexual maturity between 10 and 12 years of age. Male-female birth ratio is approximately 1 to 1. Reproductive success is greater for swamp populations than for residents of permanent lakes, as their is significantly less competition for resources in wetland habitats ("Australo-American sideneck turtles", 2003; Ernst and Barbour, 1989; Kennett and Georges, 1990; Kennett, et al., 2009; Roe and Georges, 2008b)
- Key Reproductive Features
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- Breeding interval
- Common snake-necked turtles breed once yearly.
- Breeding season
- Common snake-necked turtles breed from September to October and nesting occurs from October to December.
- Average number of offspring
- depends on amount of nest predation
- Range gestation period
- 110 to 185 days
- Average gestation period
- 150 days
- Range age at sexual or reproductive maturity (female)
- 10 to 12 years
- Range age at sexual or reproductive maturity (male)
- 7 to 8 years
- Parental Investment
- no parental involvement
The average life span of (Kennett, et al., 2009)ranges from 31 to 37 years. The lifespan of wild and captive individuals appears to be approximately equal; however, very few have been held in captivity. During dry periods, moves to more permanent bodies of water (e.g. lakes), where resource competition is high. As a result, many individuals die and thus, longevity tends to be higher in wetland habitats than in permanent lake. Females are able to withstand these pressures better than males because of their larger size.
- Typical lifespan
- 31 to 37 years
- Typical lifespan
- Typical lifespan
- 31 to 37 years
- Typical lifespan
Common snake-necked turtles frequently change habitats. During breeding seasons, males and females are known to increase movements and environmental conditions (e.g., rainfall and moisture levels) can have an impact on local densities of common snake-necked turtles. They are known to move great distances to find a suitable habitat. Although many individuals can live in the same wetland, they are generally thought of as solitary and move independently of one another. Common snake-necked turtles have good water storage capabilities, which allows them to lie dormant or estivate for extended periods of time. ("Australo-American sideneck turtles", 2003; Roe and Georges, 2008b; Roe and Georges, 2008a)
Communication and Perception
- Other Communication Modes
- scent marks
tadpoles, crustaceans, plankton and carrion. Occasionally, they prey upon terrestrial insects. Intraspecific competition has been known force movements between habitats. Prey are caught by the use of a strike and gape action, and are sucked into the turtle’s mouth by a vacuum that is created by the sudden lowering of the hyoid bone. When food resources are limited, preys upon a large variety of small organisms. ("Australo-American sideneck turtles", 2003; Kennett, et al., 2009)is carnivorous and is an ambush predator. Primary prey includes aquatic invertebrates, fish,
Predators of common snake-necked turtles include red foxes, water rats, goannas, Australian ravens, white-breasted sea eagles and dingos. When fox predation is high, populations tend to be dominated by adults, as foxes primarily prey upon juveniles and eggs. To deter predators, common snake-necked turtles emit a foul-smelling musk, or yellow fluid from their musk glands. When threatened, individuals tuck their head into their shell and lean into the threatening organism with their shell. The also perform defensive snapping when threatened. (Kennett, et al., 2009; Thompson, 1983)
- Known Predators
- foxes (Vulpes vulpes)
- water rats (Hydromys chrysogaster)
- goannas (Varanus)
- Australian ravens (Corvus coronoides)
- white-breasted sea eagles (Haliaeetus leucogaster)
- dingos (Canis lupus dingo)
tadpoles, crustaceans, and plankton. It is also a major prey item for Vulpes vulpes, which is not native to Australia. There is no information available on parasites of this species. (Kennett, et al., 2009)feeds on aquatic invertebrates, fish,
Economic Importance for Humans: Positive
The common snake-necked turtle is commonly hunted by indigenous Australians for their meat. They are also studied as biological indicators of wetland habitat quality. ("Australo-American sideneck turtles", 2003; Roe, et al., 2009)
- Positive Impacts
- research and education
Economic Importance for Humans: Negative
There are no known adverse effects ofon humans.
red foxes. This species is currently protected under state and federal legislation in Australia; however, specific conservation measures are not high priority. Currently, they are widespread and abundant throughout their geographic range. (Kennett, et al., 2009)is not listed on the IUCN Red List of Threatened Species and is thought to be a species of least concern. Important potential threats include habitat change, climate change, and nest predation by invasive
Monique Jarrett (author), University of Alberta, Augustana Campus, Doris Audet (editor), University of Alberta, Augustana Campus, John Berini (editor), Animal Diversity Web Staff.
Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
flesh of dead animals.
uses smells or other chemicals to communicate
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
A substance that provides both nutrients and energy to a living thing.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
mainly lives in water that is not salty.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
An animal that eats mainly insects or spiders.
- island endemic
animals that live only on an island or set of islands.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
makes seasonal movements between breeding and wintering grounds
having the capacity to move from one place to another.
- native range
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
an animal that mainly eats fish
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
an animal that mainly eats dead animals
- scent marks
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
- seasonal breeding
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
uses sight to communicate
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
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