Turtle history: a review of aquatic species (Introduction)

by David Turell , Thursday, March 14, 2024, 17:31 (44 days ago) @ David Turell

They play a major role in our oceans:

https://www.discovermagazine.com/planet-earth/everything-to-know-about-the-secret-world...

"In the serene yet treacherous waters of our planet's oceans, sea turtles have thrived for ages, silently helping maintain the equilibrium of aquatic life. These marine reptiles, which are emblematic of both endurance and tranquility, play vital roles in oceanic ecosystems. However, their existence is increasingly threatened by a host of serious challenges.

"Sea turtles are marine reptiles that have been navigating the world's oceans virtually unchanged for some 110 million years. They belong to the order Testudines and are known for their large shells, which offer protection from predators. Unlike many other turtles and tortoises, sea turtles cannot retract their heads and limbs into their shells, and they have adapted flippers for swimming in the ocean.

"Sea turtles play key roles in marine ecosystems, contributing to the health of seagrass beds and coral reefs, which in turn support a wide array of other marine life.

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"There are seven distinct species of sea turtles, each with its own unique set of characteristics, habitats, nesting habits, and dietary preferences. These species include:

"Green; Hawksbill; Leatherback; Loggerhead; Olive Ridley; Kemp's Ridley; and Flatback.

"Each species occupies a different niche in the marine environment, from shallow coastal waters to the open sea, and from tropical regions to more temperate zones.

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"The size of sea turtles varies dramatically across species.

"The leatherback is the largest of all sea turtles, growing up to 6 feet in length and weighing up to 1,500 pounds. Other species, like the Hawksbill and the Green sea turtle, are smaller, though they can still reach impressive sizes, with adults typically ranging from 2.5 to 4 feet in length and weighing several hundred pounds.

"On the other end of the spectrum, a Kemp’s Ridley is the smallest sea turtle, averaging under 2 feet in length and typically weighing just shy of 100 pounds.

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"The migratory behavior of sea turtles is equally impressive, with some species undertaking thousands of miles of travel between their feeding grounds and nesting beaches. Notably, female sea turtles exhibit a strong homing instinct, often returning to the exact beach where they were born to lay their own eggs.

"The diet of sea turtles varies significantly by species. While some species are omnivorous, most adult sea turtles are specialized feeders.

"For instance, green sea turtles are the only sea turtles that are herbivores, primarily feeding on seagrasses and algae, which gives them green-colored fat. Meanwhile, Hawksbills like to feed on sponges found in coral reefs. And leatherbacks and loggerheads, the giants of the turtle family, consume large quantities of open-ocean invertebrates like jellyfish, helping control jellyfish populations.

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"Sea turtles are known for their impressive longevity. They can live for several decades, with many species reaching 50 to 100 years in age. But this long lifespan contributes to their late maturity, where some species don’t breed until they are 20 to 30 years old.

"A sea turtle’s journey to maturity is also fraught with peril. From the moment they hatch, sea turtles face countless predators and challenges, which is why only about one in 1,000 to one in 10,000 hatchlings survive until adulthood.

"Sea turtles play crucial roles in marine ecosystems, from maintaining healthy seagrass beds and coral reefs to controlling jellyfish populations. However, their survival hangs in the balance, largely due to human activities.

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"Sea turtles cannot breathe underwater; they are air-breathing reptiles. However, they can hold their breath for several hours at a time. Depending on activity level, sea turtles can stay submerged for 4 to 7 hours. This allows them to undertake long dives while foraging for food or resting on the ocean floor.

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"Sea turtles are known for their remarkable nesting behaviors, often returning to the same beaches where they were born to lay their eggs. A female sea turtle can lay hundreds of eggs during a single nesting season, burying them in the sand to incubate.

"However, the survival rate of these hatchlings is extremely low, with only a few per thousand making it to adulthood.

"Sea turtles have unique sleeping habits. They can sleep at the water’s surface or underwater, surfacing for air periodically. Some species find underwater resting spots nestled in coral or mud, where they can remain undisturbed, while others simply float at the surface."

Comment: they play important roles in ecosystems across all the warm to temperate oceans