This peculiar habit enables this turtle to enjoy the best of both worlds says Stuart Blackman
Should their marshy habitat dry up, Chinese soft-shelled turtles Pelodiscus sinensis do pretty well on dry land – as long as they can find puddles in which to dunk their heads.
Biologists were long puzzled by this peculiar habit until 2012, when it was discovered that the turtles are not drinking, but peeing. Instead of excreting urea – the main waste product in urine – via their kidneys in the traditional manner, the reptiles expel it through the mouth lining.
This unconventional toilet habit is thought to a key adaptation that enables the turtles to live in both fresh- and saltwater marshes.
Passing urea by the customary route would require them to drink large volumes of water to wash it through the kidneys – and in brackish marshes that could mean ingesting dangerously large quantities of salt.
It may leave a bitter taste in the mouth, but this technique enables the turtles to produce urea in a more concentrated form and simply wash it out with a rinse and a gargle. Lovely…