Oct 11
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In the News: Bizarre turtle excretes waste through its mouth

An unusual species of turtle has been found to excrete waste substances through its mouth, according to a team of scientists in Singapore.

Photo of the head of a captive Chinese softshell turtle

The scientists were puzzled by the behaviour of the Chinese softshell turtle (Pelodiscus sinensis) as, despite needing to breathe air, it often submerged its head in water for up to 100 minutes at a time.

When they studied the turtle in the lab, the team found that it regularly dipped its head into water and rinsed it through its mouth. The rhythmic motion of its throat, not to mention the fact that it did not drown, indicated that it was still ‘breathing’ while submerged.

Photo of a Chinese softshell turtle hauled out on log, damselfly on back

Excreting urea

After testing the water, the scientists found increased levels of the chemical compound urea, a nitrogen-rich waste substance that is excreted by most vertebrates via the kidneys and passed out as urine. In turtles, urea normally passes out of the cloaca, a single orifice used for excretion and for reproduction.

However, the team’s findings showed that the Chinese softshell turtle excretes significantly more urea through its mouth than through its cloaca. This adds to previous research that indicated that this species has highly specialised mouth tissues, a fact first discussed over a century ago when it was suggested that their velvety mouth functions in a similar way to fish gills. The findings of the research have been published in The Journal of Experimental Biology.

Portrait photo of a captive chinese softshell turtle

According to Professor Ip Yuen Kwong, one of the researchers, “These results indicate for the first time that [mouth tissue] processes and rhythmic [throat] movements were involved in urea excretion in P. sinensis.”

We were greatly surprised by our novel results because it is generally accepted that the kidney is responsible for the excretion of urea in vertebrates – except fish,” he said.

Farmed for food

An odd-looking turtle with a leathery shell, the Chinese softshell turtle is native to much of East Asia, occurring in China, Japan, Taiwan and Vietnam. It has also been introduced to Thailand and the United States.

Photo of Chinese softshell turtle on ground

The Chinese softshell turtle is typically found in swampy, brackish water, and the scientists have suggested that the ability to excrete urea via the mouth may have helped this and other soft-shelled turtles to successfully invade brackish and marine environments.

To produce urine in the kidneys, the turtles would have to regularly take in water, which would be harmful when the water is too salty. By simply rinsing its mouth with the brackish water, the turtle can avoid the problems associated with drinking it.

The Chinese softshell turtle may also be able to take in oxygen through its mouth tissues.

Considered a delicacy in many parts of Asia, this species is farmed in vast numbers for food, but its wild populations also continue to be exploited. As a result, the Chinese softshell turtle is in decline, and has been classified as Vulnerable on the IUCN Red List.

Read more on this story at BBC News – Chinese turtle passes waste urea through its mouth.

View more photos and videos of turtles on ARKive.

Liz Shaw, ARKive Text Author

May 23
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World Turtle Day 2012

The 23rd of May is World Turtle Day – a whole 24 hours dedicated to highlighting the plight of the 300 or more turtle species around the world. Here at ARKive we thought we would celebrate by sharing our top turtle facts.

Did you know…

  • Turtles are found on every continent, except for Antarctica
  • The age of most juvenile turtles can be determined by the upper shell, which grows each year from a central point
  • Turtles are thought to have lived on earth for over 200 million years
  • The sex of most turtle hatchlings is dependent on the temperature which they are incubated at, with males hatching at low temperatures and females hatching when the temperature is higher

Lovely loggerheads

Loggerhead turtle image

Loggerhead turtles are regularly caught as bycatch along their migration routes

  • The loggerhead turtle has powerful jaws that can make easy work of its hard-shelled prey.
  • It is highly migratory and is known to cross oceans.

Not a jack in a box

Ornate box turtle hatchling image

Ornate box turtles are popular pets in in Europe and the United States

  • Box turtles gain their common name from their hinged shell which enables them to completely close their shell to protect themselves.
  • The male ornate box turtle has enlarged claws on its hindfeet to grip onto the female while mating.

Vast vertebrate

Leatherback turtle image

The greatest threat to the leatherback turtle is thought to be the effects of climate change

  • The leatherback turtle is the world’s largest turtle, with the average carapace (the shell covering the back) reaching around 160 centimetres and the largest recorded individual weighing up to 916 kilograms.
  • Uniquely, the leatherback turtle is able to maintain an elevated body temperature, giving it the ability to dive to depths of up to 1,000 metres in pursuit of prey.

Snappy by name, snappy by nature

Alligator snapping turtle image

The alligator snapping turtle is used as an ingredient in the delicacy 'turtle soup'

  • The alligator snapping turtle is nicknamed the ‘dinosaur of the turtle world’ due to its prehistoric, alligator-like appearance, from which it gains its common name.
  • The tongue of the alligator snapping turtle has a small, worm-like projection, which is wiggled to attract prey.

What is being done to help?

  • Shrimp fisheries are now using Turtle Excluder Devices, which only allow shrimp-sized objects to enter the nets, preventing turtles from being caught as bycatch.
  • Many species are now listed on the Convention on International Trade in Endangered Species (CITES), which means that international trade is strictly monitored and controlled. This should hopefully prevent some collection of wild turtles for the international pet trade.
  • Some nesting sites are protected during the nesting season to ensure that eggs cannot be collected and subsequently sold.
  • The protection of areas which are known to support turtle populations, as well as captive breeding programmes, could ensure the long term survival of these magnificent and fascinating reptiles.
  • Global warming poses a major threat, as populations have begun to show skewed sex ratios, with higher temperatures meaning more females than males. Although global warming is unlikely to be reversed, reducing greenhouse gas emissions may limit some damage.

Find out more about World Turtle Day American Tortoise Rescue website and for more information on reptile conservation see the International Reptile Conservation Foundation.

Hannah Mulvany, ARKive Species Text Author Intern

Mar 16
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Climate Week Species of the Day: Loggerhead turtle

This week is Climate Week in the UK, and here at ARKive we thought we’d take the opportunity to highlight some amazing species and the different ways they may be affected by climate change. 

Loggerhead turtle image

Loggerhead turtle (Caretta caretta)

Species: Loggerhead turtle (Caretta caretta)

Status: Endangered (EN)

Interesting Fact: The sex of baby loggerheads is determined by temperature.

The loggerhead is one of the most widespread of all the marine turtles and also the most highly migratory, with individuals known to cross the Atlantic and Pacific Oceans. This turtle’s common name comes from its relatively large head, which contains powerful jaws. Adults are primarily carnivorous, using their powerful jaws to crack open crustaceans such as crabs and even seemingly impenetrable molluscs such as the queen conch and species of giant clam. Loggerheads may reach sexual maturity at around 35 years old, and females appear to nest an average of three to five times in one breeding season, returning to breed every couple of years. Nesting occurs at night throughout the summer, when females drag themselves out onto beaches beyond the high-tide mark and dig nests into which around 100 eggs are laid.

Climate Change: The gender of hatchling loggerhead turtles is determined by temperature, so an increase in global temperature could lead to a skew in the sex ratio of turtles. Rising sea levels caused by climate change are another potential threat, resulting in the loss of turtle nests through flooding.

For more information on climate change, visit ARKive’s climate change pages.

Take part in ARKive’s Creative Climate Change Challenge or find out how you can get involved in Climate Week.

View images and footage of the loggerhead turtle on ARKive.

Becky Moran, ARKive Species Text Author

Sep 29
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In the News: World’s most threatened sea turtle populations identified

Almost half of the world’s most threatened sea turtle populations are found in the northern Indian Ocean, according to a new study carried out by the world’s top sea turtle experts. 

Scientists have evaluated the state of individual populations of sea turtles, enabling them to determine the 11 most threatened, as well as the 12 healthiest.

Photo of loggerhead turtle swimming

The loggerhead turtle is one of the most widespread of all marine turtles and also the most highly migratory. Several of the most threatened sea turtle populations included loggerhead turtles.

Populations at risk

The results of the study have revealed that five of the world’s eleven most threatened populations of sea turtles are found in the northern Indian Ocean, with populations of loggerhead turtles and olive ridley turtles appearing particularly at risk.

Several threatened populations of both species occur in waters and on nesting beaches around countries such as India, Sri Lanka and Bangladesh.

The report confirms that India is a home to many of the most threatened sea turtles in the world,” said Dr B.C. Choudhury, head of the Department of Endangered Species Management at the Wildlife Institute of India and a contributor to the study. “This paper is a wake-up call for the authorities to do more to protect India’s sea turtles and their habitats to ensure that they survive.”

The east Pacific Ocean from the USA to South America, and the east Atlantic Ocean off the coast of western Africa, have also been identified as areas with some of the world’s most threatened sea turtle populations.

Photo of olive ridley turtle crawling onto beach

The smallest of the marine turtles, the olive ridley turtle was identified as having a number of threatened populations in the northern Indian Ocean.

Highlighting healthy populations

The study also highlighted large sea turtle populations that are currently facing relatively low threat levels, with 12 populations identified as the healthiest in the world.

Among these healthy populations, which belong to five species including the hawksbill turtle and the green turtle, are populations with nesting and feeding areas in Australia, Mexico and Brazil.

Other areas that harbour healthy turtle populations include the southwest Indian Ocean, Micronesia and French Polynesia.

Photo of green turtle

A number of green turtle populations were identified as being among the world’s healthiest.

A conservation blueprint

The report has been produced by the IUCN and the Marine Turtle Specialist Group (MTSG), and was supported by Conservation International (CI) and the National Fish and Wildlife Foundation (NFWF).

It is the first comprehensive status assessment of all global sea turtle populations, and has been designed to provide a blueprint for future sea turtle conservation and research.

According to Roderic Mast, Co-Chair of the MTSG, CI Vice President, and one of the paper’s authors, “This assessment system provides a baseline status for all sea turtles from which we can gauge our progress on recovering these threatened populations in the future.”

Through this process, we have learned a lot about what is working and what isn’t in sea turtle conservation, so now we look forward to turning the lessons learned into sound conservation strategies for sea turtles and their habitats.

Identifying threats and priorities

As well as identifying the world’s most threatened sea turtle populations, the study looked at which threats had the most significant impact on these endangered turtles.

The study revealed that the most serious problems to sea turtles are being caused by fisheries bycatch (accidental catches of sea turtles by fishermen targeting other species) and the direct harvest of turtles or their eggs for food or turtle shell for commercial use.

Photo of a young hawksbill turtle caught in fishing net

A young hawksbill turtle caught in a fishing net. Although this species was identified as having some of the healthiest populations, it is not exempt from the many threats faced by sea turtles worldwide.

Dr Bryan Wallace, Director of Science for the Marine Flagship Species Program at CI, and lead author of the paper, said, “Before we conducted this study, the best we could say about sea turtles was that six of the seven sea turtle species are threatened with extinction globally.”

But this wasn’t very helpful for conservation because it didn’t help us set priorities for different populations in different regions. Sea turtles everywhere are conservation-dependent, but this framework will help us effectively target our conservation efforts around the world.”

A paper on the study, entitled ‘Global Conservation Priorities for Marine Turtles’, has been published in the online science journal PLoS ONE.

Find out more about sea turtles as part of Conservation International’s ‘Sea turtle September’.

Find out more about sea turtles on ARKive.

Helen Roddis, ARKive Species Text Author

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