World Sea Turtle Day - 16th June

kellyvillevetclini
Jun 15
3 min read

Ocean Wanderers: The Remarkable Life of Sea Turtles

Sea turtles are among the most captivating creatures in the ocean. With their gentle grace and ancient lineage, these reptiles have adapted to a life spent almost entirely at sea—returning to land only to nest. Despite their seemingly calm demeanor, their lives are filled with challenges, mystery, and remarkable endurance.

Built for Life in the Sea

Sea turtles may be reptiles, but they’re nothing like their land-dwelling relatives. Their bodies have evolved into streamlined shapes with powerful flippers that help them move effortlessly through the ocean. Unlike freshwater turtles, sea turtles cannot retract their limbs or head into their shells. Instead, they rely on their sleek design and strong front flippers for propulsion, while their smaller back flippers act as rudders, helping them steer with precision.

Living in salty seawater presents another challenge. If sea turtles absorbed salt at the same concentration as seawater, it would be deadly. Fortunately, they’ve developed specialized glands near their eyes that excrete excess salt, sometimes giving the appearance that the turtle is crying.

Masters of the Deep

Even though they live in water, sea turtles must breathe air like all reptiles. They cannot breathe underwater, but they’ve evolved to hold their breath for long periods—up to 7 hours when resting. During these long dives, their heart rate slows dramatically—sometimes with several minutes between beats—to conserve oxygen. This adaptation allows them to dive as deep as 290 meters (960 feet) in search of food like jellyfish, sea grass, and crustaceans.

Most sea turtles cruise along at modest speeds of 1 to 6 miles per hour, but they can accelerate to a surprising 22 mph (35 km/h) when startled.

Nesting: A Return Home

One of the most extraordinary behaviors of sea turtles is natal homing—the instinct to return to the exact beach where they were born to lay eggs. After migrating thousands of miles across the ocean, female sea turtles crawl ashore, usually under cover of night, to nest.

Nesting is physically demanding. Using her flippers, a female hauls her body up the beach, finds a safe spot above the high tide line, and begins the nesting process. First, she clears away debris and digs a shallow body pit. Then, using her hind flippers like small shovels, she creates an egg chamber about 80 cm (30 inches) deep.

Once the chamber is complete, she enters a trance-like state and lays her eggs—typically around 110 per clutch, each the size of a ping pong ball. After laying, she covers the nest, carefully camouflages it by scattering sand, and returns to the ocean. This process may be repeated 2 to 8 times in a single nesting season.

The Influence of Temperature

In a fascinating twist of nature, the temperature of the nest determines the sex of the hatchlings. Warmer sand produces mostly females, while cooler areas yield mostly males. In a single nest, temperature variation by depth can result in a mix of male and female hatchlings—cooler eggs near the bottom becoming males, and warmer eggs near the top becoming females.

The Lost Years

Once the tiny hatchlings emerge, they make a dangerous dash to the ocean—avoiding predators like birds and crabs. After reaching the sea, they disappear into the open ocean for what scientists call “the lost years”—a period of 5–10 years where their whereabouts and behavior remain largely unknown.

Only 1 in 1,000 hatchlings survives to adulthood. Those who do will eventually return to breed and, in the case of females, nest on the beach where their journey began. Males, however, almost never return to land once they enter the sea.

Why Sea Turtles Matter

Sea turtles play a crucial role in maintaining the health of marine ecosystems. They help control jellyfish populations, promote healthy seagrass beds, and contribute to nutrient cycling between the ocean and coastal environments.

But they face serious threats—from habitat destruction and plastic pollution to fishing bycatch and climate change. Understanding their life cycle is a critical first step in protecting these ancient navigators of the sea.

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