Thursday, July 31, 2014

The Tenacity of the Sanibel Sea Turtle

We do not often suggest that our readers and rental guests look at videos on line.

We realize that people do not have sufficient time to view them and are often hesitant to click on unknown links.

But this video created on Sanibel of just one tiny logger head sea turtle tells a great BIG story.  It shows a newly hatched turtle make its way from the nest to the sea, a daunting journey and it does feel that way to the viewer.  At least it did to us.  The hatchling may not have been that far away, but it feels like millions of miles in the video.

Watching a baby sea turtle  struggle out of the nest and make its way to the water is an emotional experience. Everything from footprints to driftwood and crabs are obstacles, though this gauntlet is important for its survival. Birds, raccoons, and fish are just a few of the predators these vulnerable creatures face; some experts say only one out of a thousand will survive to adulthood under natural conditions.

After an adult female sea turtle nests, she returns to the sea, leaving her nest and the eggs within it to develop on their own. The development time varies among different species and is influenced by environmental conditions such as the temperature of the sand. The developing hatchlings do not have sex chromosomes so their gender is determined by the temperature within the nest. 

Whether hatchlings are male or female depends on the temperature where they are in the nest, known as the “pivotal temperature." The temperature varies slightly among species, ranging between roughly 83-85 degrees Fahrenheit (28-29 degrees Celsius), at which embryos within a nest develop into a mix of males and females. Temperatures above this range produce females and colder temperatures produce males.

After 45 to 70 days (depending on the species), the hatchlings begin to pip, or break out of their eggs, using a small temporary tooth located on their snout.  This special function is called a caruncle. Once out of their eggs, they will remain in the nest for a number of days. During this time they will absorb their yolk, which is attached by an umbilical to their abdomen. This yolk will provide them the much-needed energy for their first few days while they make their way from the nest to offshore waters. 

The hatchlings begin their climb out of the nest in a coordinated effort. Once near the surface, they will often remain there until the temperature of the sand cools, usually indicating nighttime, when they are less likely to be eaten by predators or overheat. Once the baby turtles emerge from the nest, they use cues to find the water including the slope of the beach, the white crests of the waves, and the natural light of the ocean horizon. 

If the hatchlings successfully make it down the beach and reach the surf, they begin what is called a “swimming frenzy” which may last for several days and varies in intensity and duration among species. The swimming frenzy gets the hatchlings away from dangerous near shore waters where predation is high. Once hatchlings enter the water, their "lost years" begin and their whereabouts will be unknown for as long as a decade. When they have reached approximately the size of a dinner plate, the juvenile turtles will return to coastal areas where they will forage and continue to mature.

It's a harrowing tale from start to finish, but guaranteed if you see the efforts made, it will make your morning commute look like a piece of cake!

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