Turtle Sitting - Part One

While I was in the islands I had the opportunity to do something I’ve never done before and that was to turtle nest sit.

We “guarded” the nest every night from 6 to 10 PM starting on day 50 as the babies can immerge anywhere from 50 to 75 days after being laid.

Nowadays, because of the efforts to protect them, green turtles and hawksbills are a fairly common sight around the reefs and beaches. In fact, the Caribbean is one of the few places where sea turtles are making a come-back.

What was different about this nest is that it was a leatherback nest. They regularly nest at Sandy Point on St. Croix which, during the nesting season, is a protected beach. In other words, the beach gets closed and people are not allowed to use it.

However, a leatherback nesting on St. Thomas is rare. Even more surprising is the beach she chose; a beach, which as far as anyone knows, has never had a nest on it before. The beach is called Brewer’s Bay. As you can see from the picture above, it really is a perfect turtle nesting beach, being wide and flat, the sand being fairly soft and not too coarse. The bay is open, faces west, and offers a clear shot out to deep water. Brewer's also gave us some mighty fine sunsets.

Thanks to Erica, a walking encyclopedia on sea turtles and a curator for Coral World , I learned something new every night I was at Brewer’s. So let me tell you about the fabulous leatherback. Any mistakes are my own and I hope Erica will forgive me.

Leatherbacks are the oldest reptile in the world. Fossil records show they have remained unchanged for 400 million years! That’s a tremendous amount of time to have been living on our little planet, swimming the oceans and surviving the mass extinctions.

They are the largest of the reptiles; the females average between 800 and 1200 pound, while males can weigh as much as 2000 pounds. Think about it, that’s the size of a small car. Leatherbacks are not reef or coastal turtles, these turtles spend their lives out in the open oceans hunting jellyfish. They wander from the Arctic to the Antarctic in both the Atlantic and Pacific. They are so attuned to the deep open water that when they are in captivity they don’t recognize or understand the concept of a barrier and will bump up against the walls of whatever kind of pen they are in. They will bump up against them so long and hard they can hurt and even kill themselves.

Leatherbacks get their name from their “shell.” Unlike other turtles that have a hard carapace, a leatherback’s shell is soft, made of carotene, the same stuff as our fingernails. This tough skin covers an intricate multitude of tiny interlocking bones. Because they are barrel shaped, rather than flat like green and hawksbill turtles, they are also called trunk turtles.

As with all female sea turtles they are the only ones to return to land. Once born and after making the journey from nest to water, a male never returns to land, spending his entire life swimming the ocean. Leatherbacks are not necessarily as faithful about returning to the exact place they were born as are some other turtles. Because a female can lay as many as a 1000 eggs in one season, she may hop from beach to beach in the same general area. She can keep viable sperm alive in a special sac for up to two years. Thus she can lay a batch of eggs, get her batteries recharged, then in 10 to 20 days come back to lay more eggs. A Leatherback will lay anywhere from 10 and 12 nests in a season.

Her nest is three feet deep and she deposits 60 to 80 eggs at a time. She is the only sea turtle that lays a false layer of eggs, called water eggs, on top of the fertilized eggs. They aren’t sure why Leatherbacks do this, perhaps to hydrate the baby turtles as they immerge from their eggs, perhaps to fool predators. What’s interesting is the liquid contained within these water eggs has absolutely no DNA markers.

The babies take two days to actually hatch out of their eggs. They are folded in half when they are born, in a kind of fetal position and it takes them a while to unfold and flatten out, very like a butterfly pumping its wings after it immerges from its cocoon. Their little bodies are only 2 to 2 ½ inches long. Add the flippers and they are about 4 inches. Once hatched the babies then fight their way up through 3 feet of sand and eggs and siblings to within 2 or 3 inches below the surface of the sand where they wait until they sense the sand cooling. This usually occurs at night, sometime after sunset. They come out at night because it’s a time when there are fewer predators. But baby turtles can be fooled and sometimes immerge on rainy or overcast days.
When they immerge from the nest they head for the ocean. Once in the water they swim like mad straight out to deep water and find the ocean currents, which carry them to places where beds of Sargasso and other seaweeds gather in huge mats. There they hang out perfectly camouflaged while they eat and grow in this food rich environment. In three years they grow to about 2 feet. Eventually the Leatherback end up in the deep oceans of the world. Only one in a hundred baby turtles lives to adulthood.

Leatherbacks are unique among sea turtles in two ways. One, they are the only reptile that can self-regulate their metabolisms. Unlike other reptiles whose metabolisms will slow down or speed up automatically depending on the environment, leatherbacks have a switch they can turn off and on at will. But perhaps the most interesting thing is their thermo-regulating ability. Yes, they are cold-blooded, egg laying reptiles. And yet…they are also warm-blooded, for when they are in cold deep waters they have another switch they can turn on that warms their blood which gets pumped to their flippers.

There is some speculation that they may well be the link between reptile and mammal.

And did I get to see the miracle of their emergence?

You’ll have to wait for Part Two