Reptiles
Pig-nosed Turtle
Carettochelys insculpta · also called pig-nosed turtle, fly river turtle, pitted-shelled turtle
The pig-nosed turtle looks like two different turtles stuck together. From the shell forward it has the fleshy, pitted, leathery skin of a softshell and a comical upturned pig’s snout. But its front legs are true flippers, like a sea turtle’s, and it “flies” through the water the same way — the only freshwater turtle on Earth that does.
Overview
The pig-nosed turtle lives in the large rivers, lagoons, and estuaries of southern New Guinea and northern Australia, in fresh and brackish water. Its leathery, pitted shell reaches about 70 cm, and it has broad two-clawed flippers.
Flippers and a snorkel snout
Alone among freshwater turtles it has paddle-shaped forelimbs and swims by flapping them up and down. Its nose is drawn out into a fleshy, upturned, pig-like proboscis with the nostrils at the tip — a snorkel that lets it breathe with only its nose showing, and a tool for rooting in the bottom for food, especially figs.
A family of one
It is the sole living species of the family Carettochelyidae, an old lineage related to the softshells and the last of a group that was once widespread.
Eggs that wait for a flood
Eggs laid in sandbanks develop to the point of hatching and then pause. The fully formed hatchlings emerge only when rising floodwater triggers them, so the whole clutch hatches together into a rising river.
Status
The pig-nosed turtle is Vulnerable and declining. It is slow to mature, and its eggs and adults are heavily harvested for food in New Guinea while hatchlings are smuggled into the pet trade, on top of habitat change from mining and dams.
Pig-nosed Turtle: common questions
Why does a river turtle have flippers like a sea turtle?
It is a case of a freshwater animal independently evolving the equipment of a marine one because it lives a similar life. The pig-nosed turtle spends its time in large, open, often deep and fast rivers, lagoons, and estuaries, and it will move into coastal salt water, so it needs to be a strong, efficient long-distance swimmer rather than a bottom-walker. Flapping paddle-like forelimbs, the way a sea turtle does, is a better solution for that than the rowing motion other river turtles use, so the pig-nosed turtle has converged on the sea-turtle body plan even though it is not closely related to sea turtles and does not nest on ocean beaches.
What is the pig-like snout for?
Two things. As a snorkel, the fleshy upturned nose lets the turtle poke just its nostrils above the surface to breathe while the rest of its body and head stay submerged and out of sight, which is useful for a large, edible animal in rivers where people fish. As a feeding tool, the flexible snout, backed by a good sense of smell, is used to root through mud and leaf litter on the bottom and to nose out fruit, molluscs, and other food. The nostrils at the very tip keep working while the snout is buried.
How do the eggs know when to hatch?
The female lays her eggs in a hole in a riverside sandbank during the dry season, and the embryos develop normally until they are ready to hatch, at which point they stop and wait inside the egg. The trigger for actually breaking out is a sudden drop in the oxygen around the egg and a change in moisture, which happens when the wet season rains raise the river and flood or saturate the nest. The hatchlings, and possibly vibrations from siblings hatching, then all emerge within a short window, straight into a rising, food-rich river. This delayed, synchronised hatching is unusual and ties the turtle's breeding tightly to the flood cycle.
Is the pig-nosed turtle a good pet?
It is sold as one, but it is a poor choice and buying one is harmful. The species grows large, needs a very big, deep, strongly filtered aquarium or pond with excellent water quality, is aggressive toward other turtles and often toward tankmates generally, and is prone to skin and shell problems if conditions are not right. On top of the husbandry difficulty, almost all pig-nosed turtles in the trade are wild-caught hatchlings taken illegally from New Guinea and laundered through Southeast Asia, so the pet demand is directly driving the decline of a Vulnerable species with a restricted range.