The pig-nosed turtle (Carettochelys insculpta), also known as the pitted-shelled turtle or fly river turtle, is a species of turtle native to freshwater streams, lagoons and rivers of Australia and New Guinea. This species is the only living member of the genus Carettochelys, the subfamily Carettochelyinae and the family Carettochelyidae; however, numerous extinct carettochelyid species have been described from all over the world.

Characteristics

(video) A hog-nosed turtle swims.

The pig-nosed turtle is unlike any other species of freshwater turtle in the world. It is the best adapted turtle to an aquatic lifestyle^{[citation needed]}, with the exception of marine turtles. The carapace is typically grey or olive in color, with a leathery texture, while the plastron is cream-colored. The feet are flippers, resembling those of marine turtles. The nose looks like that of a pig, having the nostrils at the end of a fleshy snout, hence the common name. Males can be distinguished from females by their longer and narrower tails. Pig-nosed turtles can grow to about 70 centimetres (28 in) shell-length, with a weight of over 20 kilograms (44 lb).

C. insculpta in captivity

Unlike the softshell turtles of the family Trionychidae, pig-nosed turtles retain a domed bony carapace beneath their leathery skin, rather than a flat plate. They also retain a solid plastron, connected to the carapace by a strong bony bridge, rather than the soft margin of the trionychids.^[2]

The species is omnivorous, eating a wide variety of plant and animal matter, including the fruit and leaves of figs as well as crustaceans, molluscs and insects. Females reach maturity after 18 or more years old, and males at around the 16 year mark. They lay their eggs late in the dry season on sandy river banks. When the offspring is fully developed, they will stay inside the eggs in hibernation until conditions are suitable. Hatching may be triggered when the eggs have been flooded with water or by a sudden drop in air pressure signaling an approaching storm. Using these triggers along with vibrations created by other hatching turtles in the same clutch gives a better chance for survival. Using a universal trigger rather than simply waiting for incubation to finish means that they all hatch at the same time. This provides safety in numbers; also, the more turtles that hatch, the more help they have to dig through the sand to the surface. Additionally, this technique means that regardless of how late the wet season is, they will not hatch until it has started to rain.

Behavior

Pig-nosed turtles are almost entirely aquatic. Little is known about general behavior as there have been few studies in the wild. Their aggressive behavior in captivity suggests that this species is markedly more territorial than most other turtles and tortoises. They seem to display a degree of social structure during the cold dry season around the thermal vents that line some river systems they inhabit.

Habitat

C. insculpta are native to freshwater streams, lagoons and rivers of:

• the Northern Territory of Australia,
• Papua New Guinea, and
• the western half of New Guinea, which Indonesia names the West Papua region (previously Irian Jaya).

It is believed to occur in all larger, and some smaller, southern-flowing rivers of New Guinea^[3]

Systematics

This species is the only living member of the genus Carettochelys, the subfamily Carettochelyinae and the family Carettochelyidae; however, numerous extinct carettochelyid species have been described from all over the world.

Some literature claims that there are two subspecies; however, a recent paper refutes this.^[4]

Captive care

Pig-nosed turtles 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 turtle keepers. They tend to be shy and prone to stress. They get sick easily, which can cause problems with their feeding, but they are known to eat commercially available processed turtle pellets or trout chow, as well as various fruits and vegetables. Breeding is rarely an option to the hobbyist, as adults are highly aggressive and will attack each other in all but the largest enclosures.

Conservation status

The species has experienced a 50% decline in the past 20 years.^[5] Although pig-nosed turtles are protected in Indonesia under Law No. 5/1990 on Natural Resources and Ecosystems Conservation, smuggling occurs. Some 11,000 turtles captured from smugglers were released into their habitats in the Wania River, Papua Province, Indonesia on 30 December 2010. In March 2009, more than 10,000 turtles retrieved from smugglers were also released into the Otakwa River in Lorentz National Park.^[6]

References

• Species Carettochelys insculpta at The Reptile Database

• IUCN Red list of Threatened Species: Carettochelys insculpta