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Chelodina canniCann's Snake-necked Turtle

By Abigail Thiemkey

Geographic Range

Chelodina canni (Cann's Snake-necked Turtle) is found within the Roper River drainage in the northeastern area of the Northern Territory of Australia. This species is also found in drainages running from Cairns down to Rockhampton in the Cape York peninsula, Australia. (McCord and Thomson, 2002; Wilson and Swan, 2003)

Habitat

Chelondina canni can be found in freshwater habitats throughout the extreme northern/ northeastern part of Australia. It seems to have a preference for lagoons and swamps. C. longicollis, a relative of C. canni, is found within a variety of freshwater areas, and it might be assumed that C. canni will inhabit similar areas. (McCord and Thomson, 2002; Wilson and Swan, 2003)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • temporary pools

Physical Description

Chelodina canni is very similar to other Chelodina species but is distinct in having a deep, large, round and wide carapace and a wide robust head. The total dorsal surface area of the first and second marginal scutes are not noticeably different from each other in this species.

Females can have a carapace length of at least 240 mm while the adult maximumn for male C. canni is 169 mm in length. In adult males the carapace length is around 161 mm on average and 221 mm for adult females. Adult carapace is broadly oval with a deep midvertebral trough. Juveniles have noticeably round carapaces. The dorsal surface of the carapace is quite wrinkly, while the marginals are not. The posterior margin is smooth and does not show growth annuli. The hindmost marginals (also known as M12 or supracaudals) are raised slightly over the tail. On the carapace scutes of juveniles, there are a series of wrinkles in radiating patterns.

The plastron of C. canni looks upturned anteriorly and is wider, in comparison to other Chelondina species. The plastron is uniformly yellow in color with brown markings. There are also scutes that can be seen stained reddish-brown. The plastral lobe is wider than the hind lobe. The hind lobe contains a distinct anal notch. The bridge of the plastron is long but it lacks axillary and inguinal scutes.

Hatchings have a bright red-orange ventral head, neck, and plastron. The pattern on the plastron merges into the dorsal side of their marginal scutes.

In comparison to other Chelodina species, the head of Chelodina canni is wider and they have small irregular scales on the postorbital region. (McCord and Thomson, 2002; Wilson and Swan, 2003)

  • Sexual Dimorphism
  • female larger
  • Range length
    161 to 240 mm
    6.34 to 9.45 in

Development

A study conducted by Kennet et all. (1992) showed that eggs will hatch within range of 88 to 98 incubation days. Although to date little information has been published on the reproduction of C. canni, a close relative, C. novaeguineae, is an oviparous species that lays 17 - 21 eggs with an incubation time of 75 to 110 days depending on the temperature. Another relative, C. longicollis, will lay 2- 10 eggs during the early summer. These eggs will hatch three to five months later. C. longicollis females will usually lay 1- 3 clutches of eggs per year. (Kennett and Georges, 1990; Kennett, et al., 1992; Rhodin, et al., 2017)

  • Development - Life Cycle
  • temperature sex determination

Reproduction

Little information is found for Chelodina canni but it can be compared to one of its closer relatives, Chelodina longicollis. Many of the Chelodina species are polygnandrous and promiscuous. C. longicollis does not display very complex mating behaviors but it can mate with Chelodina canni. Hybridization rarely occurs but it has been shown to happen. In C. longicollis, males and females increase their movements where males will travel further distances and females will increase nesting behavior. This can be assumed for the C. canni species for the time being because they overlap in habitat and are closely related. Copulation in C. longicollis happens in water when cloacas touch while the male and female plastrons are adjacent to each other. We can assume that this could be true for Chelodina canni as well. (Kennett, et al., 1992; Kennett, et al., 2009; Murphy and Lamoreaux, 1978; Roe and Georges, 2008)

As noted, little reproductive information has been documented for Chelodina canni. We can compare them to a close relative, C. longicollis. The latter species reportedly breeds from September to October, once a year. Females will lay three clutches at this time and the eggs will incubate from 120 to 150 days. Once the eggs eggs hatch, the young are slow to mature. Males will reach sexual maturity at around 7 years and females around 10 to 12 years. We can probably assume that C. canni will have similar reproductive behavior. (Kennett and Georges, 1990; Kennett, et al., 2009; Roe and Georges, 2008)

  • Breeding interval
    Once yearly
  • Breeding season
    It can be assumed that C. canni will breed during the months of September to October.
  • 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
  • pre-fertilization
    • provisioning
    • protecting
      • female

Lifespan/Longevity

For this particular species of Chelodina, there is no known data reported yet for captive or wild populations. The close relative Chelodina longicollis has a lifespan ranging from 31 to 37 years. They live the longest in wetland habitats because of the decrease of competition for resources as compared to populations residing in permanent lakes. We may assume that Chelodina canni has a similar lifespan. (Kennett, et al., 2009)

Behavior

More research needs to be done for Chelodina canni but comparing it to C. longicollis can provide hypotheses of the behavior of this new species. Chelodina longicollis are very mobile when it comes to habitat. They will increase their movements during breeding seasons. Environmental conditions will also have an impact on the movements of C. longicollis. These turtles move overland to find suitable habitat at different times of years. They are known to be solitary even when they are within the habitat of others of the same species. (Hutchins, et al., 2003; Roe and Georges, 2008)

Home Range

Home ranges have yet to be researched for Chelodina canni and further research needs to be explored.

Food Habits

Food habits have yet to be determined for C. canni because it is a recently described species. It is known to be closely related and have a hybridization zone with the better-known Chelodina longicollis, which is a carnivore that ambushes its prey. Once they capture their prey they will suck it into their mouth like a vacuum created by the lowering of the hyoid bone. Their prey species include insects, tadpoles, frogs, small fish, mollusks, crustaceans and worms. Feeding is probably entirely under water. (Kennett, et al., 2009; Rhodin, et al., 2017; Yates, 2013)

  • Animal Foods
  • amphibians
  • fish
  • mollusks
  • aquatic crustaceans

Predation

Chelodina canni will give off a potent odor when it is threatened. Other anti-predator behaviors have not been recorded for C. canni. Like its close relatives, such as C. longicollis, this turtle has a flexible neck that can be twisted to the side under the edge of the carapace for protection against predators.

With C. canni being a relatively newly described species, predators have not yet been recorded. For a species that is closely related C. longicollis, we can assume that the predators are likely the same pending further research. C. longicollis and its eggs are preyed upon by dingos, Australian ravens, goannas, red foxes, water rats, and white-breasted sea eagles, as well as humans. (Gray, 1856; McCord and Thomson, 2002; Roe and Georges, 2008)

  • Anti-predator Adaptations
  • cryptic
  • Known Predators
    • No known predators are recorded for this species.

Ecosystem Roles

Little ecological information specific to Chelodina canni has been reported. Like its congeneric relatives, it occupies the role of a predator on small invertebrate and vertebrate prey species in the freshwater rivers, lakes, and wetlands in which it lives. It and its eggs are also preyed upon by larger predators. Apparently nothing is known of the parasites specific to this species, though it probably has its share of external (leeches, etc.) and internal parasites. (Doupe, et al., 2009; Kennett and Georges, 1990; Kennett, et al., 1992; Kennett, et al., 2009; McCord and Thomson, 2002; Wilson and Swan, 2003)

Economic Importance for Humans: Positive

Humans are known to hunt and eat the snake-necked turtles of northern Australia. Freshwater turtles are part of a balanced freshwater ecosystem. Many people enjoy seeing turtles in the wild. (Doupe, et al., 2009; McCord and Thomson, 2002; Roe and Georges, 2008)

Economic Importance for Humans: Negative

Chelodina canni is harmless to human interests. (Kennett, et al., 2009)

Conservation Status

No population size or status data has been reported for Chelodina canni. The IUCN red list has not reported on this species as of 2018. (Eisner, et al., 1978; McCord and Thomson, 2002)

Other Comments

More ecological information is needed for this recently described turtle species.

Contributors

Abigail Thiemkey (author), Michigan State University, James Harding (editor), Michigan State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

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.

carnivore

an animal that mainly eats meat

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

food

A substance that provides both nutrients and energy to a living thing.

freshwater

mainly lives in water that is not salty.

insectivore

An animal that eats mainly insects or spiders.

island endemic

animals that live only on an island or set of islands.

marsh

marshes are wetland areas often dominated by grasses and reeds.

migratory

makes seasonal movements between breeding and wintering grounds

molluscivore

eats mollusks, members of Phylum Mollusca

motile

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.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

piscivore

an animal that mainly eats fish

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

seasonal breeding

breeding is confined to a particular season

solitary

lives alone

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

References

Doupe, R., J. Schaffer, M. Knott, P. Dicky. 2009. A DESCRIPTION OF FRESHWATER TURTLE HABITAT DESTRUCTION BY FERAL PIGS IN TROPICAL NORTH-EASTERN AUSTRALIA. Herpetological Conservation and Biology, Vol. 4, No. 3: 331-339.

Eisner, T., T. Jones, J. Legler. 1978. Chemical composition of the odorous secretion of the Australian turtle, Chelodina longicollis. Copeia, 4: 714-715.

Gray, J. 1856. On some new species of freshwater tortoises from North America, Ceylon and Australia, in the collection of the British Museum. Proceedings of the Zoological Society of London, 23: 191-202.

Hutchins, M., J. Murphy, N. Schlager. 2003. Grzimek's Animal Life Encyclopedia. Australo-American sideneck turtles, Vol. Vol. 7, 2 Edition. Farmington Hills: Gale Group.

Kennett, R., A. Georges, K. Thomas, T. Georges. 1992. Distribution of the long-necked freshwater turtle Chelodina novaeguineae and new information on its ecology. Memoirs of the Queensland Museum, 32: 179-182.

Kennett, R., J. Roe, K. Hodges, A. Georges. 2009. Chelodina longicollis (Shaw 1794) – Eastern Long-Necked Turtle, Common Long-Necked Turtle, Common Snake-Necked Turtle. Conservation Biology of Freshwater Turtles and Tortoises, 31: 1-8.

Kennett, R., A. Georges. 1990. Habitat utilization and its relationship to growth and reproduction of the eastern long-necked turtle, Chelondina longicollis (Testudinata: Chelidae), from Australia. Herpetologica, Vol. 46, No. 1: 22-33.

McCord, W., S. Thomson. 2002. A New Species of Chelodina (Testudines: Pleurodira: Chelidae) from Northern Australia. Journey of Herpetology, Vol. 36, No. 2: 255-267.

Murphy, J., W. Lamoreaux. 1978. Mating Behavior in Three Australian Chelid Turtles (Testudines: Pleurodira: Chelidae). Herpetologica, 34: 398-405.

Rhodin, A., J. Inverson, R. Bour, U. Fritz, A. Georges, B. Shaffer, P. Paul van Dijk. 2017. Pp. 1-292 in Turtles of the World: Annotated Checklist and Atlas of Taxonomy, Synonymy, Distribution, and Conservation Status, Vol. 7, 8 Edition. Chelonian Research Monographs: Conservation Biology of Freshwater Turtles and Tortoises: A Compilation Project of the IUCN/SSC Tortoise and Freshwater Turtle.

Roe, J., A. Georges. 2008. Maintenance of variable responses for coping with wetland drying in freshwater turtles. Ecology, 89/2: 485-494.

Wilson, S., G. Swan. 2003. Reptiles of Australia. Princeton and Oxford: Princeton University Press.

Yates, A. 2013. A new species of long-necked turtle (Pleurodira: Chelidae: Chelodina) from the lateMiocene Alcoota Local Fauna, Northern Territory, Australia. PeerJ, 1:e170: 1-24.

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