Carettochelys insculpta (Ramsay, 1886)
                         Pig-Nosed Turtle

The Pig-Nosed Turtle Carettochelys insculpta is one of the strangest looking turtles among all others. This large turtle is distributed to southern New Guinea, Irian Jaya and Northern Australia where it lives in rivers, lagoons and estuaries. Carettochelys insculpta is even found in brackish water and sometimes in the open sea.
  
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The Pig-Nose !
 
Distribution of Carettocelys insculpta
 
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Captive born hatchling from the Wilhelma
Zoological Garden Stuttgart, Germany
 
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Plastron view of 3 month old hatchling
  
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Head and neck of adult male. Notice the fleshy nose and the white spot behind the eye. Two of many typical characteristics
  
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Plastron view
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Front limbs
 
Back limbs
 
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Egg of Carettochelys insculpta during incubation at the German Zoo Wilhelma, Stuttgart

 
 
It is very difficult to determine the sex of Carettochely insculta, unless they are almost full grown.
Below are pictures that show semi-adult animals that were raised from hatchlings. Carapax and tail form can be used to distinguish males from females. Also the behaviour will tell you about the sex of your animals once they get mature. Neckbites are used by the males to hold on the females during mating. These neckbites offten result in injuries as shown below:
  
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10 year old female Carettochelys insculpta with
25cm Carapax length.

The weight of the female is with 3300g almost
27% higher than that of the male with same size.

Note the high domed Carapax and more
massive shape of the body. The tail is less
dominant.
 
10 year old male Carettochelys insculpta with
24cm Carapax length.

The weight of the male is with 2600g much
lower than that of the the female.

Note the carpax shape and the more
massive and stronger tail.
   
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Healing Wound after Neckbite:  
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Introduction

This freshwater turtle, undoubtedly unique in appearance, is also very interesting in its behaviour. Its prominent features include the flipper-like front limbs (otherwise found only in sea turtles), the distinctive pig-nose like trunk, and the leathery skin covering carapace and plastron instead of epidermal scutes, making this turtle very interesting to scientists and hobbyist alike.
History

Carettochelys insculpta was discovered in early 1880 when Australian explorers travelled up the Fly River in New Guinea by boat. While their boat  was moored on a gravel shoal, two turtles running from the nearby river bank were caught and eaten. The remains of these turtles were later sent to the Australian Museum in Sydney, whose curator at that time, Dr. E. P. Ramsey, immediately recognised the turtle as a new species. His description proved that Carettochelys insculpta is the only survival of the once large family of Carettochelydidae. This family had been widely distributed all over Asia, Europe and North America 40,000,000 years ago.

The presence of Carettochelys insculpta in Australia itself was not known until a picture of a specimen was sent to the Australian Museum in 1970. This first Australian C. insculpta  from the Daly River had been caught and photographed by a fisherman.
Description in life:
Carettochelys insculpta is a relatively large aquatic turtle and reaches up to 600 mm in carapace length and up to 22.5 kg in weight. Instead of horny scutes that usually overlay the bony shell on turtles, the carapace is covered with a tough, leathery skin similar to that of softshell turtles. The colour of the carapace is grey to olive, while the softer skin on the plastron is entirely white. The soft parts of C. insculpta are grey to olive on top and creamy white on the bottom. The upper part of the head is grey, with a bright white spot visible behind the eyes. The spot sometimes gets paler with age and may become indistinct. A dark spot can be found on the underside of the chin. The chin itself is also creamish beige. Another distinctive aspect of the turtle's head is the prominent nose. A soft, trunk-like snout with large openings at the end has given the turtles its name: Pig-Nosed Turtle.
The nose is used to investigate the environment. Even in muddy water, the turtle is able to locate food without actually seeing it. During normal breathing at the surface the turtle inhales air through the nose. When submerged, the turtle will use the incoming water to absorb extra oxygen. Papillae in the throat are used to extract the oxygen.

Very unusual are the front limbs. Those are formed into flippers in the manner of marine turtles. On the inner side of these flippers are two claws. These claws are used to hold larger food pieces while eating and enables the turtle to hold on to river bank vegetation or fallen trees and branches on the bottom while resting. The claws are also used during mating.
The upper part of the tail is covered with crescent-shaped scales which diminish in size towards the tip of the tail. Two large skin folds extend laterally from the tail towards the back limbs of the turtle. The carapace border between the front and back limbs has nice white spots, becoming paler posteriorly. These spots may blur with age.
The huge and strong flippers on the front together with the strongly webbed hind limbs, allow rapid and effective movements under water and also permit skilful manoeuvres even in strong flowing water. Excellent acceleration can be vital to escape from predators (e.g. crocodiles). The flippers are moved synchronously from top to bottom during normal swimming, while during breathing or rapid swimming, the flippers are also moved asynchronously.

Some of this turtle's external characteristics would lead one to conclude that C. insculpta may be close related to sea turtles. However, research by Frair shows that the closest relatives of Carettochelys insculpta are the softshell turtles of the genera Pelochelys and Trionyx [5].
Distribution:

Carettochelys insculpta's geographical range is limited to lowland Papua New Guinea (New Guinea and the Indonesian province Irian Jaya). It also occurs in most coastal river systems of the Northern Territory, Australia. In Australia it is the only hidden-necked turtle, withdrawing the head straight back into the shell (Cryptodira). All other Australian turtles belong to the side-necked turtles (Pleurodira) which turn their head sideways below the rim of the carapace.
Scientists believe that C. insculpta has emigrated from New Guinea to Australia. Its adaptability to brackish water and the limited distribution in Northern Australia (in only a few coastal river systems), make it very possible that C. insculpta might have crossed the small stretch of open sea between New Guinea and Australia. This theory is reinforced by the fact that there are almost no demonstrable characteristics that could lead to describing separate subspecies. Both populations differ only in carapace length, clutch size and hatchling weight [11].
Habitat:

Preferred habitats are larger and smaller river systems with sandy or muddy bottom, but C. insculpta is also found in ponds, swamps and lagoons.
Water depth ranges from 1-3m, however during the rainy season the water level can rise up to 15m, and large parts of the lowland habitat is flooded . C. insculpta likes to hide in loose gravel or sand or it may conceal itself beneath fallen trees and branches, or among large stones.
C. insculpta can also be found in brackish water and in coastal areas. Reports of nesting activities on beaches next to those of sea turtles are reported from New Guinea. Similar behaviour is known concerning Pelochelys bibrioni in New Guinea as well.


Large aquariums, preferably with a sandy bottom are best to keep C. insculpta. If more individuals need to be kept together, hiding places and enough room must be provided. In most cases C. insculpta is aggressive, a trait that can even be in hatchlings present. In general the aggressive behaviour is directed against other individuals of the same species, but has been also observed towards Chelodina siebenrocki and Chelodina parkeri. The big strong jaws are able to cause serious injuries. Aggression and being bitten cause great stress to the subordinate turtle, thus animals should be separated if such behaviour is observed in captivity.

These turtles are excellent swimmers and require large aquariums. Although some animals sometimes rest a lot on the bottom, most of the larger animals will swim extensively. Animals become tame and often beg for food when the owner is around. However, most animals remain nervous, and even small vibrations spur the turtle to seek refuge with frenzied movements. This leads to the risk of collision  fixtures and tank walls in small aquariums, which may cause injuries. Handling the turtle can be somehow difficult since the animals flail with their strong limbs and are difficult to grab due to their leathery skin.

The water temperature should be kept around 26ºC to 30ºC. At lower temperatures the animals do not feel comfortable. They are poor eaters and are more likely to develop diseases. A basking place is not necessary, but a nesting area should be provided for larger animals if reproduction is foreseen. Good water filtration or regular water changes is also essential since C insculpta can be sensitive for fungus infections (Sphagnalium spp.). Hatchlings and subadult animals are especially vulnerable to such fungus infections in combination with stress. Spoiled food may also introduce such an infection, which in hatchlings may lead to death within a week if untreated. Treatment with 1% mercurochrome or with Acriflavine solution is generally successful [2].
Rough handling and transport (especially of larger animals) can be a problem. The soft-skinned Plastron contains many small blood vessels. If the turtle is handled outside the water (stressful in itself) the blood circulation to the plastron is increased, and turns reddish. Improper shipping boxes or even from the pressure of their own weight, may lead to serious hematomas which can prove deadly to the turtles. If possible, larger animals should be transported on a soft pad or even better partly in water.
Diet

Carettochelys insculpta is omnivorous with a tendency to eat a high ratio of herbivore food. In nature the animals feed on (partly unripe) fruits, flowers, leaves and roots of the riverbank vegetation. Fruits of figs and pandanus that drop into the water are eaten frequently but also ribbon weed (Valisneria spiralis) is one of the favourite food items which grows in the water. Animal protein in the form of crustaceans, insects, larvae, and fish supplement the diet of C. insculpta.
A large variety and amount of food is found during the rainy season, when large parts of the habitat are flooded. The rise of the water level makes additional food sources available during this time.
In captivity C. insculpta eats almost anything. Favourite items are of course different kind of fruits (bananas, figs, kiwis). But also trout pellets, "turtle pudding," dry fish, crab and clam meat as well as beef heart enriched with calcium can be given. However the diet should be balanced according to the digestive apparatus which is primarily built for herbivore food. Cuttlebone will be taken by some animals to improve their calcium metabolism.

Reproduction

Recent research has brought some light into the reproduction behaviour of C. insculpta. Sexual maturity in males is reached after 14-16 years which corresponds to a carapace length of about 300mm. Females reach sexual maturity much later (20-22 years), having reached a carapace length of 300-340mm by this time [2].
It is not clear if sexual maturity is reached earlier for animals kept in captivity. The grow rate before maturity is estimated to about 15 years for animals from the Daly River. This is the time needed for a hatchling to grow from 15mm to 300mm [2].
Males can be distinguished from females by a larger and thicker tail and by the cloaca, located further away from the plastron than the female's. This criterion can be used to distinguish the gender of animals only at a carapace length of about 200mm and larger.
Mating activities have been observed during field studies in the Daly River system. These include so-called gathering in shallow waters of up to 11 individuals. Sixty percent of all examined females showed neck injuries such as scratches and scars. Males and juveniles examined did not show these injuries [2].
Clutches are deposited during the dry season from July to October in Australia and in New Guinea as late as January (Graphic 3). Females lay up to two clutches per year, typically containing 7 to 39 eggs. However, the average clutch size in Australia is only 7 to 19 eggs. Remarkable is that females lay eggs only every second year, skipping a year between clutches [12].
Eggs are deposited during night in sandy ground. The nesting place is chosen about 50cm to 5m above the water level before the nesting hole is dug with the hind limbs. Unlike marine turtles, C. insculpta does not use the front flippers at all in nesting. The nest hole is about 22 cm in depth.
Field studies in Australia show some strange behaviour during the time when eggs are laid. As for the mating time the animals gather again, and females come ashore one at a time to explore the nesting area. They return to the water after a short time. This is repeated by other females and only test holes are dug, abandoned after a short time. Then the females come ashore actually to lay their eggs. It is not known why such large animals that have almost no terrestrial predators show such cautious and tentative behaviour [12].
Eggs are spherical, white and hard-shelled. The mean diameter is 38.7mm and mean weight is 33.7g. Remarkable is that C. insculpta has the thickest egg shells found among turtles. The average egg shell thickness is 0.39mm [9], [12].
The development of the embryo is completed after 60-70 days. Typical incubation time is 69 days at 30ºC incubation temperature. If the yolk is absorbed and the hatchlings are ready to hatch, the animals fall into some kind of aestivation before the hatching process is triggered by external factors. This hatching delay can be up to 50 days [9].
Most of the hatchlings leave the eggs at midnight, and hatching usually is triggered by the first heavy rainfall. Nature has determined a strategy that favours the hatchlings with a higher survival rate. On the one hand, waiting predators are saturated with a few hatchlings in a short time, on the other hand, food and conditions for concealment at the beginning of the rainy season are much better than during the dry season. However, this strategy is not fool-proof. In some years the beginning of the rainy season will be delayed, or it may come earlier. In this case the hatchlings are threatened with drowning, or they may desiccate.
This strategy has been investigated in detail by Webb et al. and show that most of the waiting hatchlings will emerge from the egg within 4 minutes of the eggs being submerged in water. Almost the same result is obtained if oxygen is dramatically reduced. Most of the hatchlings will leave the eggs within 10 minutes in this case[13].
Hatchlings have a high vertebral keel which is formed as the embryo develops in a folded position within the egg. The keel itself has small tubercles with a polygonal perimeter. These tubercles resemble the horny scutes of other turtles. This prominent keel slowly diminishes over the years, and can scarcely be inferred once the animals have reached full maturity.
The rim of the carapace has lateral serrations right after hatching, which stiffen after the first week. The serrations disappears within the first months.
As with many other reptiles, the pig-nosed turtle exhibits temperature-dependent sexual development (TSD). The incubation temperature determines whether the embryos develop primarily into male or female animals. Lower incubation temperatures in the range of 27.7ºC - 30ºC. will produce mainly male animals.

Normal;heading 1;
Reproduction in Captivity
Mating attempts and eggs deposited in the water have been reported several times from various zoos around the world. However two incidents of first captive breeding have been reported in 2001 from two different locations.
One hatchlings was found swimming in the main pool of an exhibit at the Bronx Zoo, among all the fish, turtles and crocodiles. The hatchling must have emerged from a clutch that has been deposited on the nesting beach in the exhibit. After intensive search of all possible nesting sites within the enclosure, more eggs were found but did not develop during incubation.
More detailed information is available from the Zoological Garden Wilhelma, in Stuttgart (Germany). There the breeding group consists of 7 large Carettochelys which share an large exhibit enclosure together with Pangasius catfish (1.2m). Most of the animals have been living at the Wilhelma for at least 27 years. On May 25th 2001, eggs were found on the bottom of the enclosure. Only two of the eggs could be salvaged and transferred into the incubator. The others were either eaten or damaged by the two large catfish or turtles itself. The eggs were incubated in Perlite at 30º C and 80% humidity. The humidity was increased after 136 days of incubation and one hatchling appeared on October 4th, 2001. The remaining egg was opened two days later, but the hatchling was already dead, probably desiccated. These results from the Wilhelma suggest that assisted hatching may be necessary for eggs of C. insculpta eggs incubated artificially as described earlier. Naturally it is hoped that this first success in captive breeding can be repeated at the Wilhelma, and emulated also by other Zoolicigal Gardens and private keepers[14].

Conservation and Management
Carettochelys insculpta is widely found in parts of its distribution range. However, its stereotypical nesting habits make pig-nosed turtles extremely susceptible to overexploitation. Eggs and adult animals are collected for human consumption throughout their range in New Guinea. Pressure on existing populations in New Guinea has increased steadily since the mobility of tribal people enables them to reach more and more remote areas. New Guinea populations are reported to have been seriously depleted in the last 20 years.

In Australia the turtles are threatened by increasing number of water buffalos. Large numbers of these buffalos trample the nesting banks and destroy riverbank vegetation upon which the turtles depend for food during the dry season.  Habitat destruction, environmental pollution and industrial activities (mining and agriculture) are considered to be the second largest threats to the pig-nosed turtle. Remember, its distribution is limited to only a few river ecosystems. Minor changes may cause large impact on the entire ecosystem.
Consumption by the Aborigines in Northern Australia is considered to be only a minor threat to the species.

Carettochelys insculpta is now listed under CITES Appendix II since October 2004

In Australia C. insculpta benefits from State and Federal legislation prohibiting the exploitation of native fauna. It is protected throughout its documented range by the National Park and Wildlife Conservation Act 1982. Export is prohibited under the Wildlife Protection.

The conservation status in Indonesia is best described as locally abundant and vulnerable, the legal status is protected. Utilisation is only allowed with special permission from the Minister and under the consent of the scientific authority.

In Papua New Guinea (PNG) the trade of turtles is strictly regulated by law as proscribed by the Fauna Act. PNG is also a CITES signatory since 1975. All exports of turtles require permits to be issued by the Conservator of Fauna. No turtles are listed in PNG as protected species which would limit legal permitted export, however C. insculpta is listed as restricted species with narrow guidelines limiting any legal export to only a few animals for legitimate scientific purposes.
However it is also known that animals are illegally traded from PNG to Irian Jaya from were they get into the pet trade [13]. Now bbeing listed in CITES Appendix II, the trade will be restricted on international basis.

Literature
[1] Bargeron, M. (1997)
The pig nose turtle, Tortuga Gazette, Volume 33, No.3
[2] Cann J. (1998)
Australian Freshwater Turtles, Beauworth Publishing Ltd,
Singapore
[3] Cann J. (1978)
Tortoises of Australia, Angus & Robertson Publishers, Hong Kong
[4] Ernst C., Barbour R. (1989)
Turtles of the World, Smithonian Institute
[5] Frair, W (1985)
The enigmatic plateless river turtle, Carettochelys, in serological survey, Journal of Herpetology, Vol.19, No.4, pp 515-523
[6] Georges A. (1987)
The pig nose turtle Warradjan, Australian Natural History, Vol.22, No.5
[7] Highfield A.C. (1990)
Encyclopedia of Keeping and Breeding Tortoises and Freshwater turtles, Carapace Press, London
[8] Webb, G.J.W. et all, (1986)
Nest, eggs and embryonic development of Carettochelys insculpta (Chelonia: Charettochelidae) from northern Australia. J. Zool. London, 1B:521-550
[9] Georges A., Rose M. (1993)
Conservation Biology of the Pig-nosed Turtle, C. insculpta
Chelonian Conservation and Biology
Volume 1, Number 1, page 3-12
Chelonian Research Foundation
[10] Doody S., Georges A. (2000)
A novel technique for gathering turtle nesting and emergence phenology data
Herpetological Review 31(4), 2000, page 220-222
[11] Webb, G., Choquenot D., Whitehead P. (1986)
Nest, eggs, embryonic development of C. insculpta (Chelonia: Carettochelidae) from Northern Australia
The Zoological Society of London (B) (1986) 1, 521-550
[12] Georges A.,Doody S.,Young J., Cann J. (2000)
The Australian Pig-Nosed Turtle.
Robey, Canberra
[13] Anders G.J. Rhodin, Vagi R. Genorupa (1999)
Conservation Status of Freshwater Turtles in Papua New Guinea
Asian Turtle Trade, Chelonian Research Foundation, page 129-136
14] Private communication with I. Koch, H. Aberle, K.J. Genzel and W. Kroll, Zoological Garden Wilhelma in Stuttgart, Germany



More interesting Carettochelys links in the Internet:

http://aerg.canberra.edu.au/pub/aerg/herps/fncchely.htm

and a very nice hoempage from Jan Matiaska:
 
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