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02-13-2006, 3:20 AM #1
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Fly River/Pig Nose Turtle Care Sheet
Ive been researching fly river/pig nose turtles for awhile and noticed that many times the same questions are asked. I hope this helps people out, though this is not from me and is cut and pasted from another website I found.
ENJOY AND FEEL FREE TO ADD YOUR OWN COMMENTS!!!
General: Fly River Turtles are large nearly exclusively aquatic freshwater exotics vaguely similar to a North American softshell but thicker & bulkier with a shorter, broader snout & more 'flipper-like' limbs. They are also known as 'pig-nosed turtles,' in light of their bulbous fleshy shout with prominently divided nostrils some consider pig-like. Overall, the animal is grey to brown on top, & white underneath. The Fly River Turtle is the sole surviving member of Family Carettochelyidae; despite superficial similarities it is not closely related to the softshell turtles.
Head: Rather rounded, round dark eyes (pupil & iris black with dark blue sclera; remind me of a great white shark's), protuberant bulbous snout, & the top & sides of the head & top of the neck are grey but the underside of the face & neck & sides of the neck are white.
Carapace: The carapace tends to be grey to live to brown with some subdued lateral white spots/patches. Like in softshells the shell is covered with leathery skin & lacks the keratin scutes of 'hard-shelled' turtles, but unlike softshells the carapace margin is inflexible.
Plastron: The plastron is largely white but pinkish in juveniles. A switch from light color to reddish in an adult may indicate irritation from poor water quality; if not corrected this can kill.
Temperature Range (°F): (All ranges are estimates)
Air Temperature: 80’s
Basking Temperature: N.A. (One of the very rare species where a basking platform in unnecessary).
Water Temperature: 79 - 86ºF1.
REQUIRES ADVANCED TURTLE CARE
A large, fairly active exclusively aquatic turtle capable of abrupt bursts of speed when startled & requiring warm tropical spacious accommodations with pristine water quality. Highly aggressive toward its own kind & some other turtles. Prone to fungal infections which can rapidly kill it. Expensive & went to CITES II in late 2004.
Noted to thrive on a diverse diet of figs, apples, other fruits, eel weed (Vallisneria sp.), whitebait (Pisces) and shrimp per one source2. I recommend inclusion of a strong brand name commercial tortoise or box turtle food (Mazuri, ZooMed, etc…) with Vit. D3 content. Given that UV-B penetration of water is sub-optimal & they generally don’t bask, dietary Vit. D3 is necessary so consider a quality Vit. D3 supplement. Flavia said her's like aquatic plants (like water lettuce), and she recommended they be part of the diet. Menikos suggested Spirulina algae wafers.
MacLeod noted in his experience all ages will eat floating food, but in Olson’s experience juveniles often would not take food from the surface and required sinking foods (Eric knew some that took years to shift to surface feeding). Flavia’s experience was midway; she said when very small they’re afraid to eat floating pellets, but after a few weeks, when used to owner and aquarium, they will. MacLeod knew of 2 F.R.T.’s fed primarily on ReptoMin when small who developed deformed, upturned shells. MacLeod recommended lower protein pellets (under 30%) for small F.R.T.’s, and supplementation with romaine lettuce, grapes, banana (which his love), cantaloupe, worms, dead minnows & other items. He’s seen a pair of youngsters do well with high quality low-protein (25%) floating Purina trout chow (now called Aquamax) as a primary food. MacLeod believed F.R.T.s over 4” better tolerate the higher protein turtle foods, although it’s not clear they require them. He reported the species is prone to fixate on a single type of food, more so than any other turtle he’s seen, so emphasize variety.
For an extensive discussion, check out Carettochelys.com’s feeding page. The author states that in his experience their plant/animal matter dietary ratio is around 2:1. Don’t miss the fact you can click on food photos at the bottom & call up extensive nutritional information on that item!
RECOMMENDED FEEDING SCHEDULE
Our standard recommendations would state for the first 6 months of life, feed commercial pellets or meaty foods such as earthworms or fish once daily, enough to diminish appetite but not gorge the turtle. After 6 months, switch to every other day feeding. Romaine lettuce, Anacharis, Water Hyacinth & other safe edible aquatic plants & other leafy greens may be offered daily for graze at will. Over time adjust diet content & schedule accounting for growth, activity level & appetite. Overfeeding high-protein foods can cause rapid growth & is believed harmful to the liver & kidneys.
These recommendations were devised for North American aquatic species ranging from red-eared sliders (who progress from predominantly carnivorous hatchlings to predominantly herbivorous omnivorous adults) to musk turtles (who remain predominantly carnivorous). Given the FRT's more herbivorous natural diet yet willingness to indulge in meaty foods, watch the protein intake - brand name commercial box turtle foods (tend to run ~ 25% protein) would be preferable to 'aquatic turtle' food (which runs ~ 35-45% protein). Since they won't get much basking (& thus UV-B light) in most captive enclosures make sure there's Vitamin D3 in the diet. Overfeeding pellets & meaty foods will likewise jeopardize water quality.
WILD & CAPTIVE HABITAT
FRTs in captivity are considered (for practical purposes) exclusively aquatic turtles ; in essence, a freshwater answer to sea turtles.
Typical Natural Habitat: rivers, estuaries, lagoons, lakes, swamps and pools, with most found in areas with sand and gravel bottoms covered with silt & averaging 6 feet deep1. Habitat water bodies tend to have forested banks1. Water bodies may also have fallen trees and branches, undercut banks, exposed tree roots and litter accumulation for cover2. For habitat photos & more extensive discussion, read Carettochelys.com’s habitat page (the authors state “…this species only occurs in limestone-based rivers. It only occurs in rivers of high pH, high conductivity and high alkalinity. This means very stable, very clear water.”)
Drawing from softshell turtle care you might recommend the tank environment be non-abrasive, including the substrate (if any) (but read on…). No land area or basking spot is required, although providing a resting area near the surface is recommended. I asked Scott Thomson about lighting issues (given that UV-B doesn’t penetrate water deeply & FRT’s generally don’t bask – he doesn’t regard UV-B lighting as necessary but recommends broad-spectrum lighting with the complete visible light range (red through blue) to provide a day/night cycle as a behavioral enhancer. (Note: If desired you can provide enough UV-B to penetrate water via a Mega-Ray mercury vapor bulb6). Flavia Guimaraes said the shell can become soft & recommended keepers provide cuttlebone. Water Quality is very important due to risk of infection (bacterial &/or fungal); very powerful filtration, large water volume, frequent water changes and low bio-load preferred. A UV-Sterilizer may be considered (for lowering microbe concentrations in the water) (Stephen Menikos considered this helpful). Aquatic plants may aid water quality if lighting is strong enough & plants the turtle won’t eat are used. You will need either high-end commercial filtration (like pond filters) or consider custom do-it-yourself options.
One Consultant opined some F.R.T.s seem to get agitated in glass-bottomed tanks, and while he’d seen some do okay in large glass-bottomed enclosures they didn’t seem ‘happy.’ He noted they like to dig (Flavia concurred). Be warned a substrate can complicate enclosure hygiene. Non-abrasive gravel is one choice. Eric Olsen had misgivings about a deep substrate as it makes the tank harder to clean and may be ingested; he kept his in a bare tank. Flavia used large outdoor enclosures with hide areas but no substrate. Carettochelys.com’s captive care page notes sand’s an option & they can bury themselves in it. Jan Matiaska finds sand too much trouble to wash except in smaller tanks. In Keeping and Breeding Freshwater Turtles5 (Page 209) Russ Gurley states there’ve been reports of captive FRT’s dying from ingesting stones or gravel, & recommends using a fine grade of sand & crushed coral as substrate (less impaction risk).
The importance of non-abrasive substrate has been called into question. Jan Matiaska doesn’t concern himself much with it & when scratched his FRT’s heal rapidly. He uses hard water around pH 7.5 (bacteria & fungi prosper best close to neutral pH), & uses shale/slate stones & wooden roots. In Keeping and Breeding Freshwater Turtles5 (Pages 207-208) Russ Gurley states keepers can add crushed coral or limestone to a sand substrate to keep pH up (& recommends pH around 7.2 – 7.5).
They are particularly susceptible to fungal white-spot (Sphagnalium sp.) & it can kill youngsters within a week2 (Mike Palmer-Allen, pers. comm. to reference.). Eric Olson stated they are moderately vulnerable to SCUD even in a fairly clean tank. He lost one to rapid onset SCUD in spite of antibiotic intervention (after about 12-14 years, an impressive time frame with a delicate species). Maxx MacLeod observed a beautiful 10 incher die of it in the spring of 2001 (despite 3 month’s treatment). Flavia noted persistent infection (believed bacterial) in a pair she acquired with infected (originally believed fungal) shell borders; despite treatment efforts, when treatment stops, the infection recurs (be sure any F.R.T. you get is healthy starting out).
One Consultant noted an interesting ‘water quality detection’ system in F.R.T.’s. Should water quality deteriorate, their plastrons may become red & inflamed. After a water change the irritation clears up in hours. In one case failure to correct the water quality for about a month resulted in a nasty infection. Be mindful that Carettochelys.com’s description page states “Hatchlings and juveniles tend to have a plastron pink colored. Little blood vessels can be seen just underneath the plastron's surface.” Oliver Römpp’s page shows another juvenile plastron shot. Learn your turtle’s normal look so you can spot changes.
The ideal pH range wasn’t clear at our first edition; Menikos recommended pH 7.0 or higher & thought they liked alkaline water and that it helped maintain health. He recommended adding 1 tablespoon of aquarium salt per 5 gallons of water, & said they do well in a brackish environment. He said his turtle's general condition (shell, etc) seemed much better in a neutral to alkaline situation. When the water got a bit acidic it tended to look a bit stressed. MacLeod’s experience differed; he worked with F.R.T.s in tanks with pH’s of 6.2, 7.0 and 8.0 & they handled the entire range; he emphasized pristine water with very low nitrate & bacterial count as key. Maxx has known F.R.T.s to thrive in different pH environments for years.
Carettochelys.com’s Scott Thomson & Jan Matiaska tell us the FRT is “…a hard water specialist turtle much like the fish of the African Lakes such as Lake Malawi. The natural conditions from which it comes from is largely rivers that have a limestone base,” “…they are high in carbonates and hence have a high but very stable pH of around 8.0 to 8.3. The KH and GH of the water is around the 18 to 25 dH.” They state “…this species only occurs in limestone based rivers. It only occurs in rivers of high pH, high conductivity and high alkalinity. This means very stable, very clear water.” Their page on water issues provides an excellent discussion of how they came to these recommendations & their practical significance.
Carettochelys.com has an extensive captive care discussion (& check out the newer, more in-depth version, too!). High-lights from that page include that when frightened it can ‘shoot like a rocket’ (potentially ramming into things), one was once witnessed to jump from one tank to another, the recommendation for well-buffered alkaline water, the option of using sand substrate, the option of adding salt to the water & the belief a more alkaline pH will discourage bacterial & parasitic infections. I was concerned about the potential for crushed coral &/or sea shells to be abrasive & cause skin lesions; I asked Scott Thomson about that & he said “It should not cause problems if the turtles are in good condition. These animals live on crushed and jagged limestone in fast flowing rivers in the wild. They are not that delicate if in good condition. Personally I tend not to use crushed shell, I think it looks bad and can have sharp edges, but it is widely used and certainly cheaper than coral.” He pointed out that calcium carbonate can buffer pH to a higher level than sodium carbonate can, & considers the alkalinity important as well as pH.
In summary, wild FRT's hail from habitat with abrasive content but hard, alkaline water which is more 'sterile' than the softer, more neutral pH waters many of us are familiar with. In the U.S., tap water is often hard & alkaline right out of the tap, & hardness & alkalinity can be increased with substrates or commercial products like Proper pH. If your water is softer & more neutral, I recommend (on theoretical grounds) using a UV-sterilizer to keep microbe counts down or at least avoiding abrasive tank content.
For adults, minimum 200 gallon tank (mine’s 7’x2’x2’), and much larger preferred. In the minimum, the turtle may have to tuck its head in to sit facing forward! A proper enclosure could weigh a few tons, so planning must include flooring capable of supporting it. Aquariums in this size range will be acrylic. Don’t count on your turtle staying under 35 cm SCL.
Both adults & young juveniles tolerate water a few feet deep, although particularly for the latter there should be 'rest areas' (i.e.: driftwood, synthetic logs, etc...) near the surface. Be warned they can move fast & 'jump' out of the water so be mindful of escape potential when filling the tank.
Recommended only as a solo turtle. Well-known for strong aggression towards its own species (although some have success with small groups in huge enclosures), and dangerous to other turtles. MacLeod strongly recommended against mixing (stating it always ends up in nipping, scarring, missing tails, etc…) & knew of a couple of Blandings & a couple of Reeves Turtles missing parts of their tails due to F.R.T.s. He believes this aggression begins quicker with turtles who resemble F.R.T.s (i.e.: softshells). Menikos also advised no mixing. Flavia believed it’s possible to mix if you raise them together from a very small size, but said they’ll attack later additions (she had 2 with an Indonesian Snakeneck Turtle). Warning: Carrettochelys.com notes Roempp had a female FRT severely bite the back limbs of an (both similar-sized) Indonesian snake-neck (Macrochelodina rugosa), & giant snake-neck (Macrochelodina expansa); a male FRT did not3. Tennessee Public Aquarium in Chattanooga had a Fly River Tank with a couple of FRTs, at least 2 Red-Bellied Short-neck Turtles, and small fish (such as Rainbow fish). Jan Matiaska has kept red-bellied short-necks (Emydura subglobosa) with them, but pointed out FRT’s do well at water temp.s too high for many turtles (even warm for E. subglobosa…) I recommend F.R.T.s be kept alone. If you mix turtles, I suggest several small ‘dither’ fish, tank ‘furniture’ to break up their line of site, provide hiding places & start when all concerned are small. Remember: it costs a LOT of money to be wrong when mixing Fly River Turtles. Aggressive behavior can be sneaky. Captive hatchlings are reputedly slow-growing per one source1, but see Hatchling Care for a different opinion! Carettochelys.com notes the aggression has been noted in youngsters only 6 months old & might even show up earlier.
Size: Wild Specimens: Length: Up to 22 inches (56.3 cm). Weight: Up to 49.5 lbs (22.5 kg). (Georges and Rose, 1993). Captive Specimens: Carettochelys.com’s Captive Care page by Scott Thomson & Jan Matiaska notes “Out of all the data about captive specimens I have come across, the maximum carapace length was approximately 35 cm.”
Breeding and Incubation
Breeding – Breeding is beyond the capabilities of most hobbyists; I am uncertain whether solitary females will lay infertile eggs without mating, & whether they will lay in water or become egg bound. Adult females should be occasionally palpated for the presence of eggs, & land area with sandy soil provided should eggs be detected. Wild F.R.T.’s typically nest in clean fine sand adjacent to water2 (Cann, 1978, Pernetta and Burgin, 1980; Legler, 1982; Webb et al., 1986; Rose, pers. obs.), but in some locales nests in mud and loams2 (Slater, 1961; Cogger, 1975; Plate 59 and pers. comm..; Groombridge, 1982; Rob Elvish, pers. comm..; Rose, pers. obs.). Carettochelys.com has a page on reproduction & notes they exhibit temperature-dependent sex determination.
Jan Matiaska (knowledgeable about the species) charted the growth of 4 young juveniles (not 'power fed' a high-protein diet) from 10-3-02 through 4-4-04. All 4 started out around 7.0 cm SCL (~ 2.75"). Growth occurred a fairly constant rate through 4-4-04, at which point they ranged from 14.0 - 15.6 cm SCL (~ 5.5 - 6.2"). One 'middle' specimen's measurements were 10-3-02 6.9 cm (to start), 4-2-03 8.6 cm (~ 6 months), 10-1-03 12.6 cm (~ 1 year), 4-4-04 15.2 cm (~ 18 months).
Activity Cycle: Diurnal (day-time active). Flavia said they sleep the whole afternoon and are active at night and early morning, cruising and playing mainly at night! In her experience, it’s best to feed them at night because late morning and early afternoon they sleep. Jan Matiaska’s FRT’s are most active (gliding & exploring) in morning & evening hours, rest at the bottom by day & sleep at night.
Behavior: One consultant noted they tend to be slow-moving and mellow but can bolt quickly when startled, and are generally non-aggressive with short necks & slow motion but can bite very hard if poked at. He noted some like a head rub in the water; your mileage may vary but be careful. Eric Olsen noted juveniles don't routinely "cruise" in the water column as the adults do, but usually stay on the bottom and are inactive much of the time; MacLeod on the other hand has found even the young to be fairly active. Whether this is due to individual specimen differences or subtle husbandry differences isn’t clear; there are a range of experiences
Availability in the Hobby: FRT's have historically shown up fairly often on major online classifieds but in late 2004 they were classified as CITES II; combined with the lack of captive breeding U.S. availability may rapidly dwindle. Pricing ranges from ~ $350 - $700 apiece in the U.S.A., but quite variable (I saw a Classified for large ones at $1,500 apiece; can be had cheap in some parts of Asia; Flavia said $23 U.S. in Malaysia). Captive breeding is very rare so assume the acquisition is wild-caught (or hatched from a wild-harvested egg) unless known otherwise. Jan Matiaska reported that prior to being listed CITES II he'd seen them priced ~ 80 - 100 Euros in Europe; expect prices to rise from there.
Climate: Tropical species that does not hibernate.
Known U.S. Legalities: CITES II.
Originally Posted by JD7.62
12-06-2006, 11:07 PM #2
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Here's some additional species-specific info:
The water in the tank should be clean at all times. If a constant in-out-flow cannot be maintained, use a powerful filter and change the water as frequently as possible, because the species is very vulnerable when it comes down to fungi or bacterial infections. On various occasions, Scott told me: "In order to decrease the bacterial and parasitical threat, increase the water pH. You will find the added benefit of both clearer and more stable water quality once you stabilise the pH". In order to keep fresh water at a high pH, Scott suggests to use a coral or crushed sea shell substrate. "It causes lots of buffer every day at first until it stabilises. With attention it will eventually sit on 8.0-8.4 no worries. Make sure you use marine pH test kits and marine buffer [i.e. not sodium carbonate but calcium carbonate]." (Scott Thomson, 2002). The average water temperature in the areas Carettochelys species occur is 30C (85F).
There are several reports on how the Carettochelys species is prone to suffer from fungal disorder, one of which says: "Hatchling and sub-adult specimens are particularly susceptible to fungal white spot (Sphagnalium sp.) which if not treated promptly, kills young animals within a week (Mike Palmer-Allen, pers. comm.). It can be effectively treated externally by removing all loose skin and scabs and treating liberally with 1% Mercurichrome (Windholtz et al., 1983: 5698) or Acriflavine Solution (Windhotlz et al., 1983: 116), which is allowed to dry on the skin before the animals are returned to the tank." (Georges & Rose 1993)
03-11-2010, 12:43 AM #3
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The CITES report on this turtle is 9 pages long. Here's a condensed revision of the document:
Here's a condensed version of the CITES 9-page document on FRTs as it pertains to trade. I've omitted the passages pertaining to turtles originating from Australia and Papua New Guinea since trade is banned from these countries. The following passages pertain to Indonesia only:
3. Utilization and Trade
3.1 National utilization
Indonesia: Cann (1978, 1998) noted that locals living along the Eilanden River (Irian Jaya [West Papua]) relished the species? eggs as food; all nests examined on riverine sand anks in 1972 had been disturbed, and baskets filled with about 200 eggs each were observed. Cann (1998) also described that, before about 1970, river travel and associated egg harvest were extremely limited due to the insecure conditions in the region. Samedi and Iskandar (2000, presumably based on Maturbongs, 1999) noted that a field study undertaken at the Vriendschap River in Merauke Regency, Irian Jaya, in August?September 1998 recorded 84,000 eggs collected by 7 collectors. In all of 1998, half a million eggs were collected from the banks of the Vriendschap River. In the entire Merauke Regency, collection of Carettochelys eggs has been estimated recently to amount to 1.5?2
million eggs annually (Samedi and Iskandar 2000). Many of these eggs are traded and consumed locally, but a proportion is incubated in sand-filled buckets and the hatchlings subsequently sold for the pet trade.
Maturbongs (1999) noted that local peoples along the Vriendschap River usually only captured adult turtles for consumption. According to his survey and interview results, egg collection has expanded massively in recent years, since 1997, due to the influx of egg harvesters from outside West Papua, originating from Toraja and Ujung Pandang. Maturbongs (1999) specifically stated that local communities barely obtain benefits from egg harvesting. External collectors organize local villagers to carry out the labor of harvesting eggs, for which they are paid 10,000 Rp (USD 1.12) per day, but from which 6,000 Rp is deducted for two meals daily, 1,000 Rp for coffee and 2,000 Rp for cigarettes, leaving a net income of 1,000 Rp (USD 0.11) per day as reward for over-harvesting the
community?s natural resources.
3.2 Legal international trade
Neither Australia nor Papua New Guinea allow export or domestic trade of the species. Export from Indonesia is only permitted in the case of captive-bred animals, which is interpreted as including animals hatched in captivity from wild-collected eggs incubated under semi-controlled, captive conditions (Samedi and Iskandar 2000). No export quota was set for the species by the CITES Management Authority in 1998 (Samedi and Iskandar 2000).
3.4 Actual or potential trade impacts
The general consensus is that recently intensified egg collection, to a large part driven by the aim to supply hatchlings to the international pet trade, is presenting a clear threat to the survival of the species in West Papua (Maturbongs 1999) and is also affecting the exploitation and conservation status of the species in Papua New Guinea (Rhodin and Genorupa, 2000). Inclusion of Carettochelys in CITES Appendix II is primarily intended to facilitate and reinforce existing export restrictions in the three Range States, by providing an international dimension to the species? protection. This will greatly increase opportunities to reduce illegal trade in the species by imposing trade control measures in the importing countries. At present, only the Lacey Act of the United States of America provides comparable complementary protection. Inclusion of the species in CITES Appendix II should not compromise the subsistence utilization of the species by native communities throughout its range. This could facilitate limited, sustainable harvest and trade with
associated socio-economic benefits by and for these communities.
3.5 Captive breeding or artificial propagation for commercial purposes (outside country of origin) Indonesian legislation allows for incubation in captivity of wild-collected eggs (ranching) (Samedi and Iskandar 2000). WWF Sahul Bioregion conducted a study of captive incubation to identify the possibilities for future captive breeding as a means to reduce harvesting pressure on wild populations, but only provisional results were available (Tjaturadi, 1999).
4. Conservation and Management
4.1 Legal status
Indonesia: Carettochelys insculpta is given national protection status under Government Regulation Act No. 7 and 8 of 1999, which is in application of Law No.5/1990 concerning the Conservation of Biological Natural Resources and their Ecosystems incorporating Decrees 327/1978 of the Ministry of Agriculture (Noerdjito and Maryanto 2001). No utilization in any form is allowed for species listed in this protection status, except with special permission from the Minister and under the consent of the Scientific Authority for special circumstances, such as research and captive breeding, and no capture or export quotas are set (Samedi and Iskandar 2000).
Carettochelys insculpta is not specifically covered by bilateral or inter-governmental legislation. Under Notice of Strengthening the Trade Management on Turtles and Tortoises, issued on 17 June 2001, the People?s Republic of China suspended all commercial imports of all turtles from Indonesia, including Carettochelys insculpta.
03-11-2010, 12:50 AM #4
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Here's some info on Breeding FRTs:
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.
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.
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.
Clutches are deposited during the dry season from July to October in Australia and in New Guinea as late as January. 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.
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.
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.
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.
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.
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.
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.
03-11-2010, 12:54 AM #5
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