Name: Mary River turtle (Elusor macrurus)
Where it lives: Mary /Moonaboola River, Queensland, Australia
What it eats: Mostly aquatic plants, but sometimes seeds, fruits and insect larvae
Why it's awesome: This turtle has a distinctive, punk-like appearance, thanks to green algae growing from its head and body that helps it hide from predators in its aquatic home. It also has two long, fleshy protrusions called barbels sticking out from its chin that help it sense its surroundings.
In addition to its unusual appearance, the Mary River turtle also has a neat trick up its sleeve — or rather, its butt.
"It can spend days at a time submerged, managing to 'breathe' underwater — a feat achieved by very few reptiles — through specialised organs inside its cloaca [an orifice found mostly in non-mammalian vertebrates for intestinal, urinary and genital tracts]," Rikki Gumbs, a researcher at the EDGE of Existence programme, a conservation initiative focusing on unique and overlooked species, told Live Science in an email.
While some freshwater turtles use their skin for aquatic respiration, using cloacal glands allows them to be submerged for longer. In the case of the Mary River turtle, this can be for up to 72 hours.
Related: Can turtles really breathe through their butts?
The glands — called cloacal bursae — are covered with papillae, which are small structures lining the walls of the bursae. Oxygen in the water diffuses across the papillae and into the turtle's bloodstream.
The Mary River turtle is also unique: No other turtle is closely related to it. "It is the only surviving species in its genus," Gumbs said. "It is thought the ancestors of the Mary River turtle diverged from all other living turtle lineages more than 18 million years ago — several million years before our ancestors and those of the orangutan parted ways."
Despite being prolific in the pet trade for decades in the 1960s and 1970s, its distribution in the wild was a mystery to scientists until they were finally found in the wild and formally described as a species in 1994.
