Washington: Scientists have discovered that the common musk turtle possesses an extraordinary organ that allows it to breathe underwater and stay submerged for many months – a tiny tongue lined with specialized buds.
Rather than using the tongue for eating, the turtle use it to exchange oxygen.
"I was very surprised, I really didn’t expect that," the BBC quoted zoologist Egon Heiss, who is studying for his PhD at the University of Vienna in Austria, as saying.
The scientists discovered this phenomenon while studying the feeding habits of the turtle – while the adult ones took their food and dived underwater to feed, the juveniles made unsuccessful attempts to swallow it on land.
A closer examination of the turtle’s tongue revealed why.
The common musk turtle has a weak and tiny tongue covered with and surrounded by specialized bud-like cells called papillae – that are used to draw in oxygen from water that passes over them.
"We knew that an organ for aquatic respiration must be present somewhere but finally discovered it accidentally," said Heiss.
"We found the large papillae in the throat and were immediately fascinated," Heiss added.
He and his colleagues believe the musk turtle’s tongue is likely to be an ancient trait.
Some turtles cannot breathe underwater at all and must come to the surface at least every few hours to gulp air.
Other species, such as the side-necked turtles of Australia, cope by using specialised cavities in their rear, known as cloacal bursae, to draw in water and remove the oxygen.
However, musk turtles lack cloacal bursae and their skin is relatively thick and lacks a well-developed capillary network, according to Heiss.
"I truly believe there’s still a lot to discover," he continues.
"This study shows how plastic adaptations to certain environmental circumstances can be in turtles."
Details are published in journal The Anatomical Record.