Description
Original detailed descriptions of the morphology of Carettochelys insculpta are provided by Ramsay (1886), Waite (1905) and Walther (1922) and are summarized by Cogger (1975) and Pritchard (1979a). Carettochelys insculpta is a heavy bodied turtles, up to 22.5 kg in weight and 56.3 cm in length (Rose, unpublished data). Colouration is rich grey, olive-grey or grey-brown above and white, cream or yellowish below. The jaws are cream and there is a pale streak behind the eye. The species is cryptodirous, that is, the vertebral column in its neck flexes in the vertical plane when the head is withdrawn. There are no epidermal scutes overlying the shell, which is covered instead with a continuous skin. The carapace is relatively deep, with a median keel toward the rear. The peripheral bones are complete and well-developed, so there is no flexible shell margin. The plastron, although small, forms a continuous plate without even a median fontanelle. Several of the plastron elements are not rigidly ossified together, but rather have cartilaginous connections which allow a certain amount of flexibility. The limbs are paddle-shaped, like those of sea turtles, each with two claws. The dorsal surface of the tail is covered with a single line of crescent-shaped scales which decrease in size from the base to the tip. Prominent folds of skin extend laterally on each side from the undersurface of the tail across the thigh region and down the hind limbs. The nostrils are at the end of a prominent fleshy proboscis. Mature males can be distinguished from females of the same size by the tail which is larger in males to enable successful copulation.
On emergence, hatchlings have well formed strong limbs but an extremely soft plastron and carapace. The plastron has a deep crease where folding of the body has occurred during incubation. The periphery of the shell comprises loose flaps of skin, which become firm after about one week to form a serrated margin. Hatchlings also have a tuberculate median keel; a poorly defined and transient polygonal outline around each of these tubercules may be homologous to the scute seams of other turtles (Pritchard, 1979a). The tubercules are lost as the turtles grows and the median keel is present only on the posterior quarter of the carapace by the time the turtles matures.
Hatchlings from New Guinea weigh 29.6 +/- 0.32 g on average and have an average carapace length of 53 +/- 0.25 mm (Rose, unpublished data), whereas the equivalent data for the South Alligator River are 24.7 +/- 0.84g and 56.1 +/- 0.91 mm (Georges and Kennett, 1989) and for the Daly River are 20.5g and 41.1 +/- 1.22 mm (Webb et al., 1986). They exhibit the full range of shell colour variation shown in the adults, even within single clutches, and the pale streak behind the eye is present. There may be small light patches on the carapace radiating to the peripherals, and these are more prominent toward the rear of the carapace.
Pig-nosed turtle
Habitat
The pig-nosed turtle
can be found in the rivers, billabongs, lakes and waterholes of the Alligator, Victoria and Daly Rivers in the Northern Territory. The species also inhabits similar environments in Papua New Guinea.
Diet
The pig-nosed turtle
is omnivorous, but most of the natural diet consists of fruits that have fallen into the water from surrounding trees, particularly figs. Other items include mangrove fruits, pandanus fruits, freshwater prawns, and shellfish.
In captivity
pig-nosed turtle
have become available through the exotic pet trade, with a few instances of captive breeding. While juveniles are small and grow slowly, their high cost and large potential size makes them suitable only for experienced aquatic turtles keepers. They tend to be shy and prone to stress, which can cause problems with their feeding, but they are known to eat commercially available processed turtles pellets or trout chow, as well as various fruits and vegetables. Breeding is rarely an option to the hobbyist, as adults are highly aggessive and will attack each other in all but the largest enclosures.
Care and Feeding
In the wild, pig-nosed turtle
feed almost exclusively on plants and fruit, with only a small part of their diet made up of snails, insects, and small fish (Ernst and Barbour, 1989). Therefore, they will do best in captivity if fed a diet that is plant-based while foods that are high in protein and fat should be avoided. Offer low protein aquatic turtles foods, such as Reptomin® or spirulina wafers. Some of their favorite foods are water lettuce, water hyacinth, watercress, duckweed, and Vallisneria, a common aquarium plant.
Occasionally, small pig-nosed turtle
are reluctant to feed off of the surface of their enclosure. If this is the case, strap a piece of romaine lettuce or other greens to a rock using a rubber band and sink it to the bottom.
Environment
Because of their size, pig-nosed turtle
or Fly River turtles require the most spacious enclosures of any freshwater aquatic turtles. These freshwater turtles require clean, warm, heavily filtered water with a large number of aquatic plants for security and proper food.
In their natural habitat of Australia and New Guinea, rivers typically have a high pH (7.2 to 7.8), yet they have seem to be somewhat adaptive to most water conditions. Add crushed coral or limestone to the sand substrate in their enclosure to keep pH up. Also, limestone rocks or slate can be used as the basis for the cage decorations instead of, or in addition to, driftwood.
pig-nosed turtle
can also be kept in large tubs or stock tanks to give them even more room for swimming. Maintain the water at 7.2 to 7.5 pH and keep a 6 - 8” (15 - 20 cm) substrate of ¾ washed river sand and ¼ crushed coral in the bottom. The addition of crushed coral helps maintain the higher pH required by this species.
Make sure that you add an efficient filtration system to keep their water ultra-clean. You can use a large pre-filter which is raised off of the sandy bottom with bricks to keep it from clogging with sand that the turtles kick up in their search for food.
Though this species doesn’t bask, add a shop light fixture with UVB-emitting bulbs and a spotlight above. These will help you view the turtles and are advantageous for the aquatic plants in their enclosure.
The floating and submerged aquatic plants are nibbled on daily and some are completely devoured, especially the Vallisneria (a delicacy from their native habitat) and duckweed. Clean the clogged filters and replace the plants weekly, as the turtles seem to enjoy them so much.
