Freshwater turtles

Freshwater turtles are commonly seen in most Queensland waterways.  There are about 14 species (and a number of subspecies) recognised from Queensland, all belonging to the family Cheluidae.

The Eastern Snake-necked Turtle, Chelodina longicollis - photograph by John Cann.

The Eastern Snake-necked Turtle, Chelodina longicollis
Photograph by John Cann.

Mary River Turtle

The articulated skeleton of a Mary River Turtle, Elusor macrurus.

The `bum-breathing’ Fitzroy River Turtle, Rheodytes leucops - photograph by John Cann.

The 'bum-breathing' Fitzroy River Turtle, Rheodytes leucops.
Photograph by John Cann.

There are two basic body forms, the short-necked turtles (Elseya spp., Elusor macrurus, Emydura spp., Rheodytes leukops and Wollumbinia spp.) and the long-necked turtles (Chelodina spp. and Macrochelodina spp.), which have extremely long, snake-like necks. Unlike the sea turtles and many foreign freshwater turtles, the Australian cheluids fold their necks side-ways under the protective edge of the shell (pleurodirous).  They have clawed, webbed feet and most species have distinct barbels on the chin. 

Most freshwater turtles leave the water to lay their eggs.  One species, Macrochelodina rugosa, has developed an unusual nesting strategy.  This turtle lays its eggs underwater, in a nest dug into the bottom of a shallow pool.  The pool then recedes during the dry season until the nest is on land.  The eggs delay development while submerged and laboratory tests have shown that even when they are submerged for 12 weeks they will still develop normally when removed from the water.  The significance of this behaviour is not fully understood but it may prevent the eggs being eaten by terrestrial predators.  By the time the nest is above the water level, the signs and odour of the nesting turtle will be largely gone.

In some of the short-neck turtles (Rheodytes and Elusor), the cloaca is lined with numerous finger-like projections that act in a similar manner to the gills of a fish.  By drawing water into its cloacal cavity, the turtle can satisfy much of its oxygen needs.  The turtles armed with this 'bum-breathing' system need surface only infrequently for air.

The Common Snake-necked Turtle (Chelodina longicollis) is often seen crossing roads during or after rain.  This turtle is highly mobile and moves away from permanent water bodies to feed in seasonal lagoons that, for a time, offer a rich abundance of food.  These turtles are often killed by traffic and there is evidence that they are declining in heavily settled areas.  They were once common in Brisbane waterways but are now rarely seen.

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