Sea turtles spend most of their lives in the ocean, surrounded by salty seawater. It’s only natural to wonder – do these marine reptiles ever actually drink water? As it turns out, the answer is more complex than a simple yes or no.

If you’re short on time, here’s the quick answer: Sea turtles have special glands that allow them to process the salty seawater and extract freshwater. So while they don’t drink water in the conventional sense, they do have methods to intake and process freshwater from their marine environment.

Sea Turtles Have Specialized Glands to Extract Freshwater

Salt Glands Filter Out Salt

Sea turtles have amazing adaptations that allow them to obtain freshwater from their marine environment. One key adaptation is their salt glands, which are specialized glands located around the eyes that function to extract excess salt from the bloodstream and excrete it as a concentrated saline solution from the nose.

This prevents the buildup of high salt levels, known as hypernatremia, which would be fatal to the turtle.

The salt glands work through a countercurrent exchange system, allowing sea turtles to drink seawater and filter out the salt. As the turtle drinks, the salt gets absorbed from the gut into the blood. The circulatory system then carries the salty blood to the salt glands.

Here, special channels maximize contact between the salty blood and secretion cells in the glands. The cells actively pump sodium and chloride ions out of the blood, producing a concentrated brine solution that gets expelled through the turtle’s nose when it exhales.[1]

Research has shown the salt glands can excrete salt at exceptionally high rates, allowing sea turtles to maintain proper salt balance even when drinking seawater. Loggerhead turtles, for example, have been found to excrete salts at rates over twice that of ocean water – more than double the salinity![2] This gives them great ability to stay hydrated in their ocean environment.

Tear Glands Around the Eyes

In addition to the specialized salt glands, sea turtles have tear glands around their eyes that produce excess fluid to flush out salt. The tear glands work in conjunction with the salt glands to get rid of sodium chloride from the turtle’s body after drinking seawater.[3]

Studies observing sea turtles found they produce tear-like secretions continuously from the lacrimal glands around their eyes. This tear fluid mixes with the salty secretions from the nasal salt glands when they exhale through their nose.[4] The extra tear fluid helps dilute and flush out the salt, preventing a damaging buildup in the turtle’s body.

Researchers found the rate of tearing increases after sea turtles drink saltwater, suggesting the tear glands ramp up secretion to help deal with the extra salt load.[5] So the tears aren’t emotional – they serve an important physiological role for maintaining salt balance!

Together, the salt glands and tear glands allow sea turtles to inhabit the ocean by giving them the remarkable ability to extract freshwater from seawater through specialized adaptations. Next time you see a sea turtle, think about how its unique glandular systems help it survive!

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1385870/
[2] https://www.sciencedirect.com/science/article/abs/pii/S109564330300258X
[3] https://www.amnh.org/exhibitions/mythic-creatures/land-creatures-of-the-sea/sea-turtle-adaptations
[4] https://www.jstor.org/stable/3892505
[5] https://www.sciencedirect.com/science/article/abs/pii/S109564330300258X

Hatchlings Get Water From Food

Sea turtle hatchlings are truly amazing little creatures. As soon as they emerge from their sandy nest, their journey to the ocean begins. Being so small and vulnerable, you may wonder how they survive those first critical days and weeks after hatching.

One thing is for certain – they don’t head to the ocean for a drink of water! Let’s take a look at how sea turtle hatchlings get the water they need to survive.

Yolk Sac Provides Hydration

Sea turtle eggs contain a yolk sac that provides nutrition to the developing embryo. But the yolk sac doesn’t disappear once the hatchling emerges. It is absorbed into the turtle’s abdominal cavity and continues to provide nutrients and hydration for several days after hatching.

This yolk sac allows the tiny hatchlings to make their trek from nest to ocean without needing any external source of food or water. It gives them the energy and hydration they need to crawl across the beach and paddle through the waves to reach the relative safety of the open ocean.

Marine Food Sources Provide Moisture

Once the yolk sac has been absorbed, the young sea turtles rely on small marine creatures for nutrition. Their diet consists of plankton, algae, jellyfish, and tiny fish. These marine foods have high water content, providing both nutrition and hydration.

Some interesting facts about hatchling diets:

  • Jellyfish are made up of over 90% water.
  • Plankton are aquatic organisms that consist largely of water.
  • Algae thrives in water and contains lots of moisture.

By feeding on these water-rich marine organisms, sea turtle hatchlings can get all the hydration they need without ever taking a drink of sea water. Their bodies are perfectly adapted to extract moisture from their food source.

Special Glands Filter Out Salt

On very rare occasions, a hatchling may accidentally swallow some sea water. Sea turtles have special glands near their eyes that filter out the salt. The excess salt is then excreted as a concentrated saline solution from their nostrils.

This helps them maintain proper water and salt balance, even when living in the ocean. While ocean water would be deadly for humans to drink, sea turtles have evolved the ability to extract hydration from it when needed.

Incredible Survival Instincts

The fact that sea turtle hatchlings can embark on their epic ocean migration without any external source of food or water is simply amazing. Their yolk sac, moisture-rich diet, and specialized glands allow them to survive and thrive in their watery home.

These incredible creatures demonstrate the amazing survival instincts and adaptations that enable them to perpetuate their ancient lineage. When you think about sea turtle hatchlings, remember that they are born equipped with everything they need for their precarious journey across the sand and through the waves.

Most Hydration Comes From Their Gelatinous Diet

Jellyfish are Mostly Water

Sea turtles thrive mostly on a carnivorous diet comprised of jellyfish and other gelatinous sea creatures that have high water content. Jellyfish are made up of 95-98% water, giving sea turtles a very hydrating food source (1).

By ingesting jellyfish, sea turtles can fulfill up to 70% of their daily water needs. Their flesh is not only bursting with H2O, but it helps supplement essential nutrients like salts, amino acids, lipoproteins, and lipids (2). Every bite of jellyfish offers that dual benefit of water and energy.

Some loggerhead sea turtles, for example, get such an abundance of hydration from jellyfish they hardly ever drink water directly. That gelatinous diet perfectly adapts them to their saltwater habitats.

Sponges Absorb a Lot of Water

Sea sponges are another go-to food source providing tremendous hydration. With bodies comprised of 95% water (3), they too offer that ideal balance of fluids and nutrients. Their porous bodies are excellent at trapping particles from ocean currents, including microorganisms, dead organic matter, and algae that again deliver additional dietary perks.

A sea turtle feasting on sponges not only gets refreshed with water, but gains health bonuses from whatever nourishing goods sponges have filtered from the sea. According to an Australian Institute of Marine Science report, green sea turtles, for example, can fulfill nearly 1/3 of energy needs just from ingesting sea sponges (4).

For many sea turtle species, their carnivorous cravings for gelatinous aquatic creatures sustain them completely, from protein to hydration.

Between protein-packed jellyfish and super absorbent sponges loaded with micro-nutrients, sea turtles thrive on an energizing and hydrating carnivorous diet perfectly tailored to ocean-dwelling reptiles.

They illustrate brilliantly how having adapted to eat what provide the most available nutrition in their habitats substantially reduces the need to directly drink water from surrounding seas.

References:

(1) AskNature: Jellyfish Bell is Composed of up to 98 Percent Water

(2) National Geographic: Here’s What a Turtle Sees When It Looks at Jellyfish

(3) Reef Builders: The Sponge – Good Reasons Why They’re Essential to Reef Ecosystems

(4) Australian Institute of Marine Science: What do green turtles eat

Basking for Freshwater Sources

Drinking Dewdrops

Sea turtles live in the ocean, but they still need fresh water to survive. An amazing way they get freshwater is by drinking dewdrops! Early in the morning when the sun first comes up, dew forms on plants near the shore.

The sea turtles will find these dewy plants and lick the droplets off the leaves and stems. This gives them a refreshing drink of pure water.

Sea turtles have even been observed specifically seeking out dewy plants to get their morning water. They will come out of the ocean, find the dew-covered plants, and have a nice cold drink before heading back to the salty seas.

It’s an ingenious way for these aquatic reptiles to meet their need for some daily freshwater.

Absorb Water Through Cloaca

Sea turtles have another trick for getting freshwater that doesn’t require leaving the ocean at all. They can actually absorb some freshwater through their cloaca when swimming in certain ocean conditions.

The cloaca in reptiles and birds is a cavity used for both digestive, urinary, and reproductive systems. Sea turtles have special glands lining their cloaca that can absorb freshwater when the surrounding seawater has less salt, such as areas where a river meets the ocean.

The change in salinity triggers their cloacal glands to pull in the less salty water. This gives them a small internal source of freshwater without drinking or leaving their aquatic habitat.

So while sea turtles spend nearly all their time swimming in the ocean, they’ve evolved some clever ways to meet their need for freshwater too. They lick dew from shoreline plants in the morning, and absorb diluted seawater through glands in their cloaca.

This allows them to thrive in their ocean realm while getting essential freshwater resources.

When Kept in Captivity, Turtles Need Fresh Water

Sea turtles kept in captivity, whether for rehabilitation, research, or display, require access to fresh clean water to stay healthy. Here are some key points on providing proper freshwater access for captive sea turtles:

Hydration Is Essential

While sea turtles get most of their water needs from their food, having a source of fresh water available is still very important. Dehydration can quickly become life-threatening for a sea turtle. Providing a constantly available clean water source is essential.

Multiple Access Points

The enclosure or tank should have multiple access points where turtles can easily get to fresh water when needed. These access points should be positioned at different locations and different water depths to accommodate different species and sizes of turtles.

Proper Filtration and Maintenance

A strong filtration system is needed to keep fresh water clean and free of harmful bacteria. Water quality should be tested regularly. Partial or complete water changes may be needed periodically as part of routine tank maintenance.

Species-Appropriate Parameters

Water temperature, pH, salinity, and other parameters should be maintained at appropriate levels for the species of sea turtle. For instance, sea turtle rehabilitation guidelines recommend water temps of 22–28°C for green and loggerhead turtles.

Enclosure Design Considerations

The enclosure should allow adequate air flow across the water surface for proper gas exchange. Basking areas and haul-out spaces should be provided as needed depending on species. Proper lighting is also important.

By providing clean fresh water tailored to a sea turtle’s needs, facilities can help keep captive turtles healthy while they recover or contribute to conservation through research and education.

Conclusion

While sea turtles live in salty ocean waters, they have evolved specialized systems to extract the freshwater they need from their marine environment and diet. Key adaptations like salt glands, hydrated foods, and basking behaviors allow sea turtles to survive without relying on conventional drinking.

The next time you see a sea turtle swimming by, remember that they have some clever strategies that allow them to go without drinking water as we typically imagine it!

Similar Posts