Jennifer Viegas, Discovery News


Sept. 19, 2008 -- Before his death two years ago this month, "Crocodile Hunter" Steve Irwin and his father discovered a unique turtle species that, as Irwin said, can "breathe through its bum."

Researchers are now racing to save the rare and unusual turtle, Elseya irwini, which appears to be dying out as a result of human activities, according to scientists at James Cook Unviersity in Queensland, Australia.

Irwin and his father Bob first found the turtle after accidentally yanking one up on a fishing line during a 1990 family camping trip. It was later determined that the turtle only lives in two places: the Broken-Bowen River and the lower Burdekin River in Australia.

Ivan Lawler, who is now researching the turtle in hopes of saving it, told Discovery News the species was "probably always somewhat restricted in distribution, but changes in water quality, flow regimes and so on from human (induced) change" have reduced its range further.

Lawler, a JCU ecologist, believes only 5,000 of the turtles exist in the wild today.

The turtle's remaining habitat has extremely poor food sources, which could be why it evolved the odd breathing technique.

Although the turtle can take in air from its nostrils, the second breathing method allows it to also absorb air from water that flows in through its behind, via an organ called the cloaca. It can therefore stay underwater for very long periods of time.

"It might be that (cloaca breathing) allows them to maintain position in flowing currents while feeding, that it helps them to escape predation or that it allows them to reduce energy expenditure on surfacing and thus get by with a lower-energy diet," Lawler explained.

He and physiologist Suzy Munns have found that the species "seems to have a very low metabolic rate, even for a turtle."

Although the river-dwelling turtle appears to minimize energy use to make the most of a poor diet, the researchers suggest it is getting a "bum deal" when it comes to food. The turtle's remaining food sources appear to be items most other animals can't -- or won't -- stomach.

Lawler explained that some turtles must make entire meals out of eucalyptus leaves, which can be poisonous to other animals.

"They also sometimes eat cane toads," he said. "We don't know if they eat them fresh, and thus while the toad is toxic, or after it has died in the water and therefore the toxins have leached out."

He and his colleague are currently feeding test turtles, including two other local species, a range of different foods at different temperatures to more precisely estimate the turtles' metabolic rates. They also hope to determine why the turtle doesn't move to other, more food-rich points in the rivers, but they suspect the eating of eggs by predators, such as feral pigs, poses a threat.

In the future, the researchers hope their findings will help inform water management policies, improving the turtle's chances for survival. As if the turtle doesn't face enough hardships already, proposals are now on tap to build a dam at the site, which could wipe out the species.

The Queensland Government has already drafted an environmental impact report that identifies the turtle as being "of high conservation significance." The report further mentions that the dam "would compromise the reproduction and survival of the species," due to the destruction of sandbars used for egg-laying.

Saving the turtle would be a fitting tribute to Irwin, who worked tirelessly on many conservation projects, bringing such otherwise unknown animals to the media forefront.

Lawler said, "one thing that biologists I know often remark upon is that he reached an audience that wasn't receptive to the other naturalists."

"It's really the mainstream that needed to be reached," he added, "and he found a way to do it. That was a valuable contribution."