Soft-shelled turtles urinate through mouthOctober 11, 2012
Chinese soft-shelled turtles are exquisitely adapted to their aquatic lifestyle, sitting contentedly on the bottom of brackish muddy swamps or snorkelling at the surface to breath. According to Y. K. Ip from the National University of Singapore, they even immerse their heads in puddles when their swampy homes dry up: which intrigued Ip and his colleagues. Why do these air-breathing turtles submerge their heads when they mainly depend on their lungs to breathe and are unlikely to breathe in water? Given that some fish excrete waste nitrogen as urea - in addition to ammonia - and expel the urea through their gills, the team wondered whether the turtles were plunging their heads into water to excrete waste urea through their mouths, where they have strange gill-like projections. Ip and his colleagues publish their discovery that turtles effectively urinate through the mouth in The Journal of Experimental Biology at http://jeb.biologists.org.
Purchasing turtles from the local China Town wet market and immersing them in water for 6 days, the team measured the amount of urea that passed into the turtles' urine and found that only 6% of the total urea that the animals produced was excreted through the kidneys. Removing the turtles from the water and providing them with a puddle to dip their heads into, the team noticed that the turtles submerged their heads occasionally and could remain underwater for periods lasting up to 100 minutes. They also calculated the excretion rate of urea through the mouth by measuring the amount of urea that accumulated in the water and found that it was as much as 50 times higher than the excretion rate through the cloaca. And when the team injected urea into the turtles and measured their blood- and saliva-urea levels, they realised that the saliva-urea levels were 250 times greater than in the blood. The turtles were dipping their heads into water to excrete urea through their mouths.
Knowing this, the team reasoned that the animals must produce a specialised class of protein transporters in their mouths to expel the waste and, as these transporters can be deactivated by phloretin, the team decided to test the effect of phloretin on the turtle's ability to excrete urea. When the turtles were supplied with phloretin in their puddle of water, they were unable to excrete urea from their mouths when they submerged their head. And when the team analysed the turtles' cDNA, they found that the animals carried a gene that was very similar to urea transporters found in other animals. Finally, they checked to see if the turtles express this gene in their mouths and found evidence of the mRNA that is necessary to produce the essential urea transporter, allowing the reptiles to excrete urea waste through the mouth.
So, why do Chinese soft-shelled turtles go to such great lengths to excrete urea through their mouths when most other creatures do it through their kidneys? Ip and his colleagues suspect that it has something to do with their salty environment. Explaining that animals that excrete urea have to drink a lot, they point out that this is a problem when the only water available is salty - especially for reptiles that cannot excrete the salts. The team says, 'Since the buccopharyngeal [mouth and throat] urea excretion route involves only rinsing the mouth with ambient water, the problems associated with drinking brackish water... can be avoided'.
REFERENCE: Ip, Y. K., Loong, A. M., Lee, S. M. L., Ong, J. L. Y., Wong, W.P. and Chew, S. F. (2012). The Chinese soft-shelled turtle, Pelodiscus sinensis, excretes urea mainly through the mouth instead of the kidney. J. Exp. Biol. 215, 3723-3733.
This article is posted on this site to give advance access to other authorised media who may wish to report on this story. Full attribution is required, and if reporting online a link to jeb.biologists.com is also required. The story posted here is COPYRIGHTED. Therefore advance permission is required before any and every reproduction of each article in full. PLEASE CONTACT email@example.com
THIS ARTICLE IS EMBARGOED UNTIL THURSDAY, 11 October 2012, 00.15 HRS EDT (04:15 HRS GMT, 05:15BST)
The Company of Biologists
Related Turtles Articles:
This research suggests that that warmer temperatures associated with climate change may lead to higher numbers of female sea turtles and increased nest failure.
The pathogen, Vibrio cholerae can colonize the surfaces, as well as the intestines of soft shelled turtles.
Debris from logging in tropical forests is threatening the survival of hatchling leatherback turtles and the success of mothers at one of the world's most important nesting sites in Colombia.
Is it a boy or is it a girl? For baby sea turtles it's not that cut and dry.
Bones from dead turtles washed up on Mexican beaches indicate that Baja California is critical to the survival of endangered North Pacific loggerhead sea turtles, which travel some 7,500 miles from their nesting sites in Japan to their feeding grounds off the coast of Mexico.
A long-running research and conservation project is helping save an at-risk species of turtle.
Endangered leatherback sea turtles are known for their open-ocean migratory nature and nomadic foraging habits - traveling thousands of miles.
A new generation of threatened hawksbill sea turtles is thriving in the protected waters of Glover's Reef Atoll, Belize, evidence that efforts to protect these and other marine species in one of the world's great barrier reef systems are working, according to WCS (Wildlife Conservation Society) and the Belize Fisheries Department.
Why do so few turtle eggs hatch on Raine Island, the largest and most important nesting site for green turtles in the world?
Decades of unregulated industrial waste dumping in areas of the Great Lakes have created a host of environmental and wildlife problems.
Related Turtles Reading:
Turtles All the Way Down
by John Green (Author)
“A wrenching and revelatory novel.” – The New York Times
“Green finds the language to describe the indescribable. . . . A must-read for those struggling with mental illness, or for their friends and family.” —San Francisco Chronicle
#1 New York Times Bestseller • #1 Wall Street Journal Bestseller • #1 International Bestseller • USA Today Bestseller
It’s quite rare to find someone who sees the same world you see.
Sixteen-year-old Aza never intended to pursue the... View Details
National Geographic Readers: Turtles
by Laura Marsh (Author)
Take a dip with turtles in this exciting reader. Packed with beautiful and engaging photos, kids will learn all about these fantastic reptiles. This level 1 reader is carefully leveled for an early independent reading or read aloud experience, perfect to encourage the scientists and explorers of tomorrow! View Details
Turtles (Bullfrog Books: My First Pet)
by Cari Meister (Author)
In Turtles, early readers will learn how to care for a pet turtle and find out what it needs in its tank. Vibrant, full-color photos and carefully leveled text will engage emergent readers as they discover what it takes to be a pet owner. A labeled diagram helps readers understand what a turtle needs, while a picture glossary reinforces new vocabulary. Children can learn more about pet turtles online using our safe search engine that provides relevant, age-appropriate websites. Turtles also features reading tips for teachers and parents, a table of contents, and an index. Turtles is part of... View Details
One Tiny Turtle: Read and Wonder
by Nicola Davies (Author), Jane Chapman (Illustrator)
"Simple, lyrical words and bright, acrylic doublepage pictures convey the astonishing facts about the loggerhead sea turtle. . . . A powerful nature story for a young audience." -- BOOKLIST
Far, far out at sea lives one of the world's most mysterious creatures, the loggerhead turtle. For thirty years she swims the oceans, wandering thousands of miles as she searches for food. Then, one summer night, she lands on a beach to lay her eggs -- the very same beach where she herself was born. Nicola Davies's lyrical text offers fascinating information about the journey of the tiny,... View Details
Turtles Coloring Book for Grown-Ups 1 (Volume 1)
by Nick Snels (Author)
The perfect book for turtle lovers. Fifty amazing designs of turtles. Try to be like the turtle - at ease in your own shell.
Vivid colors, great illustrations and imagination are all you need to keep calm and relaxed!
Each picture is printed on its own 8.5 x 11 inch page so no need to worry about smudging.View Details
Good Night Little Turtle
by David Cunliffe (Author), Tiffany Cunliffe (Illustrator)
It's time for bed. But first, our little turtle needs to say goodnight to his animal friends. We follow him on a short adventure as he says goodnight, one-by-one, to his friend the sheep, bird, frog, dog, rabbit and lion. He brushes his teeth, gets a bedtime story of his own and drifts off to sleep. This rhyming story, with lovable, bright and vividly-colored animal friends, is sure to catch the attention of even the most wiggly children - and their parents. If you enjoy this book, please check out Jetpack Giraffe, it's one of our favorites! View Details
Turtles (Complete Pet Owner's Manual)
by Hartmut Wilke (Author)
Turtles is a book in Barron's series of Complete Pet Owner's Manuals . This manual offers detailed instructions on turtle care, safe handling, feeding, health care, and terrarium construction and maintenance. Written especially to introduce inexperienced and prospective pet owners to the pleasures and duties of pet care, Barron's Complete Pet Owner's Manuals also make fine guides to pet care for older children. These heavily illustrated books are filled with helpful information on purchasing, housing, feeding, health care--and where applicable, grooming and training... View Details
Turtle in Paradise
by Jennifer L. Holm (Author)
In Jennifer L. Holm's New York Times bestselling, Newbery Honor winning middle grade historical fiction novel, life isn't like the movies. But then again, 11-year-old Turtle is no Shirley Temple. She's smart and tough and has seen enough of the world not to expect a Hollywood ending. After all, it's 1935 and jobs and money and sometimes even dreams are scarce. So when Turtle's mama gets a job housekeeping for a lady who doesn't like kids, Turtle says goodbye without a tear and heads off to Key West, Florida to live with relatives she's never met. Florida's like nothing Turtle's ever seen... View Details
by Douglas Wood (Author), Cheng-Khee Chee (Illustrator)
Who is God?
Is He a wind that is never still?
Is He a rock that never moves?
Is He high above or here among us?
Venerable Old Turtle answers quietly: God is all of these things.
Old Turtle first burst upon the publishing scene in 1992, and it was instantly recognized as a classic fable about ecology, peace, and the interconnectedness of all beings. Simple yet profound, it has since brought hope and inspiration to children and adults around the world. View Details
Phonics Power! (Teenage Mutant Ninja Turtles) (Step into Reading)
by Jennifer Liberts (Author), Patrick Spaziante (Illustrator)
This Step into Reading boxed set includes 12 full-color phonics readers featuring Raphael, Donatello, Leonardo, and Michaelangelo of Nickelodeon’s Teenage Mutant Ninja Turtles. Each book features a specific phonics concept that will give boys and girls ages 3 to 7 the tools they need to begin reading on their own. View Details