The Galápagos Islands, located off the coast of Ecuador, are home to some of the world’s most unique and diverse wildlife, including the green turtle (Chelonia mydas). These creatures, belonging to the family of chelonids (Chelonioidea), are a must-see for anyone interested in wildlife photography or marine biology. As a photographer, the opportunity to capture the beauty of these turtles is truly a lifetime experience. With their distinctive appearance and graceful movements under the waves, green turtles have captivated the hearts of visitors and nature enthusiasts alike.
In this blog, we will take a closer look at the green turtles of Galápagos and explore their fascinating world. We will look at their sleeping and breathing habits, social behaviour, natural predators, human impact and challenges ahead. This blog post displays a small collection of my underwater photos taken on the islands of Santa Cruz, Isabela, Cristobal, and Floreana. Although my photography skills are limited, I hope these photos can show a glimpse of the beauty and grace of these wonderful creatures in their underwater world. I am humbled by the privilege of capturing these moments and I hope it can inspire others to appreciate and protect these magnificent green turtles of Galápagos.
Green Sea Turtles: Keystone Species of the Ocean
Green sea turtles are considered a keystone species in the ecosystems where they live due to their important role in maintaining the health and balance of these habitats. In seagrass beds, for example, green sea turtles help to control the growth of the seagrass by trimming the tops and leaving the roots intact. This helps to maintain healthy seagrass beds, which in turn provide habitat and feeding grounds for a variety of marine organisms, including fish, crustaceans, and mollusks.
In coral reef habitats, green sea turtles have a symbiotic relationship with reef fish, such as the yellow tang. The yellow tang swims alongside the turtle and feeds on the algae, barnacles, and parasites that grow on its shell and flippers. This cleaning behavior helps to reduce drag and improve the turtle’s swimming ability, while also providing a food source for the yellow tang. In addition, the presence of green sea turtles in coral reef ecosystems helps to maintain the balance of the ecosystem by controlling the growth of algae and providing habitat for a variety of marine organisms.
Majestic Sea Turtle. In the crystal-clear waters surrounding Floreana Island in the Galápagos, Ecuador, a majestic sea turtle gracefully navigates the ocean currents – a breathtaking sight that reminds us of the beauty and fragility of our natural world.
Sea Turtles: Mastering the Art of Sleeping in Water
Sea turtles are air-breathing reptiles, which means they must come to the surface of the water to breathe. They can hold their breath for long periods of time, with some species able to remain underwater for up to five hours. When a sea turtle surfaces to breathe, it exhales a burst of air from its lungs, producing a distinctive sound that can be heard above the water.
Despite spending the majority of their lives in the water, sea turtles still need to rest and sleep. Unlike humans, who go into a deep sleep when they rest, sea turtles enter a state of “sleep swimming“. During this time, they remain alert to their surroundings and can surface to breathe as needed. This ability to sleep while swimming helps sea turtles conserve energy while remaining vigilant against predators.
Sea Turtles’ Bedtime Habits. Sea turtles have been known to return to the same sleeping location night after night, wedging themselves under rocks below the surface or under ledges in reefs and coastal rocks.
The Diverse Diet of Green Turtles
Green turtles have a diverse diet that changes throughout their life. While juveniles are carnivorous, feeding on a variety of marine invertebrates, fish and their eggs, adults are mostly herbivorous, consuming large amounts of seagrass and algae. Most adult sea turtles are strictly herbivorous. The slow growth rate of green turtles is due to the low nutritional value of their diet, which leads to their body fat turning green because of the consumed vegetation. Interestingly, this diet shift has an effect on the turtle’s skull morphology, with the serrated jaw helping them to efficiently chew on their preferred diet of seagrass and algae.
Sea turtles have a unique feeding strategy where they graze on seagrass beds, taking bites of the grass and leaving behind telltale tracks on the seabed. They consume a wide variety of seagrass species, including Thalassia spp., Syringodium spp., and Halodule spp. In addition to seagrass, green turtles also consume red and green algae species like the green seaweed Gayralia, sea lettuce (Ulva lactuca), filamentous red alga (Bostrychia), and lobster horns (Polysiphonia). These algae are a good source of protein, which is especially important for young turtles as they need high-quality protein to support their rapid growth. Green turtles also play an important role in the ecosystem as they help to maintain the health of seagrass beds by grazing on the plants and preventing overgrowth.
Turtle Feast: Underwater Dining with Sea Turtles. A sea turtle indulging in a macroalgae feast as it swims under the waves.
Lung Adaptations of Sea Turtles
Sea turtles have evolved unique adaptations to survive in their aquatic environment, including specialized lungs that enable them to breathe air efficiently and rapidly replace the air in their lungs during short surface intervals. They are able to extract oxygen from the air more efficiently than land animals due to their lungs’ large surface area. This is achieved by a network of small air sacs that are distributed throughout the lungs, which increase the surface area available for gas exchange. The air sacs are lined with tiny blood vessels called capillaries, which allow oxygen and carbon dioxide to diffuse quickly between the lungs and the bloodstream.
When a turtle surfaces to breathe, it quickly exhales and inhales air in a single explosive movement. This rapid exchange of air allows the turtle to quickly replace the air in its lungs and take in fresh oxygen. Sea turtles can take in a large volume of air in a single breath, which can be up to 80% of their lung capacity. This allows them to extend their dive times and spend more time underwater before having to surface to breathe again.
One of the benefits of this rapid exchange of air is that it prevents gases, such as nitrogen, from being trapped in the lungs during deep dives. This is important because if gases become trapped in the bloodstream, they can cause a condition known as decompression sickness or “the bends.” This condition can be fatal if not treated promptly.
Take a Breath: Green Turtles’ Need for Air. Turtles come up for air, surfacing in the crystal-clear waters of the ocean to take a deep breath and continue their journey in the underwater world.
The Predators of Sea Turtles Throughout Their Life Cycle
Green sea turtles face predators throughout their life cycle. Adult green sea turtles are mainly preyed upon by larger sharks, including tiger sharks (Galeocerdo cuvier). In some areas, such as Hawaii, tiger sharks have been observed to specifically target adult green sea turtles. However, human beings are also a major predator of adult green sea turtles, with hunting and poaching contributing to their decline in many areas.
Juvenile green sea turtles are also preyed upon by a variety of predators, including crabs, small marine mammals, and shorebirds. Their eggs are vulnerable to predation by a range of predators, including raccoons, foxes, and feral pigs, which often raid the nests on the beaches where the eggs are laid. Once the hatchlings emerge from the nests, they are at risk from predators such as gulls, crabs, and various fish species.
For example, in Florida, USA, 90% of green sea turtle nests are destroyed by predators, primarily by raccoons, which dig up the eggs and consume them. Other predators of hatchlings include gulls, crabs, and a variety of shorebirds. In some areas, human development and activity can also impact the survival of hatchlings, as they can become disoriented by bright lights and crawl away from the sea instead of towards it. The high level of predation on hatchlings and eggs is one of the reasons why only a small percentage of green sea turtle hatchlings actually reach maturity.
One Fin, One Heart: Sea Turtle’s Unwavering Spirit. Despite losing a frontal fin, this determined sea turtle continues to glide through the ocean, reminding us that strength and perseverance come in many forms.
The Social Side of Sea Turtles: Mating, Rafting, and Site Fidelity
Green sea turtles are known to be solitary creatures, but they do exhibit some social behavior in certain situations. For example, during the mating season, males compete with each other for access to females. This can involve aggressive behavior such as biting and ramming.
In addition, juvenile green sea turtles have been observed engaging in a behavior known as “rafting.” This involves groups of turtles floating together on the surface of the water, sometimes for hours at a time. The reasons for this behavior are not fully understood, but it may serve a social function, such as allowing the turtles to exchange information or to conserve energy.
Green sea turtles also exhibit phylopatry, also know as site fidelity, which means they return to the same nesting beaches year after year. This behavior may be related to the turtles’ ability to navigate using the earth’s magnetic field, as well as their ability to detect and remember the unique magnetic signatures of their home beaches.
A Playful Encounter: Sea Lion and Marine Turtle in Galápagos. A playful sea lion and a serene marine turtle share a moment in the clear waters of Galápagos, a beautiful display and coexistence in the natural world.
Mirror Image: Two Sea Turtles Gaze into Each Other’s. These two sea turtles seem to be staring into a mirror as they share a moment of peaceful reflection.
The Impact of Boat Traffic on Sea Turtles and Mitigation Efforts
Boat traffic can have a significant impact on green sea turtles. Collisions with boats and propellers can cause injuries and fatalities. Sea turtles can be difficult to see when they surface to breathe, and boats moving at high speeds may not have enough time to avoid them. In addition, boat strikes can cause serious injuries to the turtles, including damage to their shells, flippers, and internal organs.
In addition to collisions, boat traffic can also cause disturbances that affect the behavior and health of sea turtles. The noise and vibrations from boat engines can disrupt their feeding, mating, and nesting activities. The wake from boats can also erode nesting beaches and damage seagrass beds, which are important habitats for sea turtles and other marine species.
To mitigate the impacts of boat traffic on sea turtles, various measures have been implemented, such as speed limits in areas where sea turtles are known to occur, exclusion zones around nesting beaches and other important habitats, and education campaigns to raise awareness about the risks of boat strikes and the importance of protecting sea turtles.
Battle-Scarred Beauty: A Marine Turtle’s Resilience. This resilient marine turtle swims with a cracked shell, a reminder of the impact that boat traffic can have on the delicate ecosystem of our oceans.
Challenges and Conservation Efforts for Green Turtles in Galápagos
However, the green turtles of Galápagos face many challenges in their natural habitat. These include habitat loss, pollution, fishing and boat striked. Green turtles feed mainly on seagrasses and algae, which are in decline due to the destruction of mangroves and coral reefs. Additionally, turtles are often caught in fishing nets or hunted for their meat and eggs, leading to a decline in their populations.
Despite these challenges, efforts are underway to protect and conserve these magnificent creatures. Conservation organizations are working to restore seagrass and mangrove habitats, reduce pollution and fishing practices, and raise awareness of the importance of green turtle conservation. By capturing and sharing their beauty through photography, we can help inspire others to appreciate and protect these wonderful creatures for generations to come.
For the green turtles of Galapagos...
In the Galapagos, a wonder untold,
where the sea is a treasure trove of gold,
lies a creature, gentle and serene,
with a heart of grace, a soul supreme.
The green turtle swims, a creature so rare,
with flippers strong, and a shell to bear,
it feeds on the plants, that grow beneath,
the waves of the ocean, a symphony of peace.
Its journey is long, a journey of might,
from the shores of its birth, to the waters so bright,
where the coral reefs thrive, and the sunlight dances,
and the turtle moves on, in its tranquil prances.
But danger is near, and threatens its life,
the boat propellers, with blades sharp as a knife,
and the sharks, who roam the seas so wide,
all threaten the turtle, from reaching its tide.
So let us protect, this treasure of the sea,
and keep it safe, for eternity,
for the green turtle, is a gift from the deep,
a symbol of peace, a soul so serene.
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