GRUMPY SEA TURTLES - 3RD WONDER OF WATERWORLD

When Dito was diving in the Galapagos, he took a picture of the Third Wonder of Waterworld - Grumpy Sea Turtles.

There are plenty of reasons sea turtles should feel grumpy.

Probably the biggest reason is because sea turtles are endangered species.

There are seven species of sea turtle that have survived for millions of years.

Green Sea Turtle - Endangered
Loggerhead Sea Turtle - Threatened
Kemp’s Ridley Sea Turtle - Endangered
Olive Ridley Sea Turtle - Threatened
Hawksbill Sea Turtle - Endangered
Flat back Sea Turtle - Status Unknown - Lack of Data
Leatherback Sea Turtle - Threatened

The Grumpy Sea Turtle looks grumpy for other reasons. It has to do with the bony structure of his skull. He has a grumpy skull that puts a scowl on his face. The scowl is not his fault.

Once sea turtles are full grown, the male and female are the same size.

The leatherback is the Goliath of sea turtles. An adult leatherback is 6 to 9 feet long and 3 to 5 feet wide. He is the heavyweight champion of the turtle world at up to 1500 pounds.

Others sea turtles are 2 to 4 feet long and weigh substantially less.

Sea turtles are built for speed with a shell and body tapered fore and aft. There is no place in their shell in which to retract their head and flippers presumably because those cavities would create drag and make it difficult to swim at high speed.

I am sure that sea turtles are smart because they don’t go to the polar oceans. Cold water does not work for them. In fact cold water causes “cold stunning”.

Sea turtles cannot tolerate water temperatures below 45 to 50 degree Fahrenheit. If a sudden shift in water temperature happens in a severe cold snap, the turtles become cold stunned. Their heart rate goes down and their circulation decreases as they slip into a lethargic state. Cold stunning can kill a turtle if it is severely immobilized and unable to migrate to warmer seas.

After a sea turtle hatches, the challenge for survival begins. They make a mad dash for the sea running through a gauntlet of predators that want to have them for lunch. The hatchlings need a safe place where it’s possible to survive, and many of them swim out to the Sargasso Sea where they can hide out and feed.

Freshly hatched sea turtles have a one percent chance of survival into adulthood. Out of 100 eggs that hatch, 99 of the hatchings are devoured by other species.

Fast food restaurants popularized chicken tenders, and unfortunately, the new hatchlings are turtle tenders - the favorite fast food of numerous aquatic and avian species.

Sea turtles are the beneficiaries of the Covid 19 pandemic. Turtles need beaches on which to lay their clutch of eggs, and since humans have been banned from the beaches of the world, the sea turtles now have better access to the beach.

It takes about ten years for turtles to mature and start to reproduce. The pelagic sea turtles return to the area where they hatched - sometimes to exactly the same beach to lay their eggs.

The female sea turtle digs a circular hole that is 16 to 20 inches deep, and places between 50 and 350 soft shelled eggs in the hole. Then she fills the nest with sand and does her best to hide the nest. Sometimes she digs other nests without depositing eggs in those nests presumably to create fake nests to fool predators. The female lays anywhere from 1 to 8 clutches of eggs in a single reproductive season.

By some strange twist of biologic fate, sea turtle gender is determined by the temperature of the sand in the nest. Warmer temperatures create female sea turtles, and cooler temperatures create males. I wonder what happens to the unfortunate sea turtles who incubate in nests that are neither hot or cold.

Some sea turtles are omnivores and others are herbivores, and some change their dietary preferences as they mature.

Although sea turtles live in salt water, their body fluids are hypotonic to the ocean. For a sea turtle to survive, they have to get rid of excess salt to maintain their body in a hypotonic state.

To achieve the hypotonic state, sea turtles have a salt gland the excretes excess salt. Sea turtles have a tear gland (lachrymal gland) that produces hypertonic tears and helps clear salt from their body.

Leatherback turtles eat jellyfish which means it has a high salt diet. To deal with this, the leatherback has larger lachrymal glands than other sea turtles, and this adaption makes it easier and more efficient to clear excess salt from his body. The concentration of salt in the tears of a leatherback are almost twice the level found in other sea turtles.

When a baby sea turtle hatches and hits the ocean for the first time, the hatchling is dehydrated from the struggle of hatching and the arduous rush to the sea, and he has to quickly hydrate and fire up his salt gland to establish hydration and electrolyte balance. Just another miracle of Mother Nature at work.

Most sea turtles are cold blooded, but leatherbacks can maintain a body temperature 14 degrees Fahrenheit warmer than ambient water temperature. I suspect that part of the ability to achieve thermoregulation in leatherbacks has a great deal to do with their larger body mass.

Green sea turtles in the Pacific Ocean have been seen out of the water basking in the sun warming themselves up.

Sea turtles don’t have gills. They have lungs, and they must surface in order to breathe.

Sea turtles spend most of their lives under water, and they excel at holding their breath. How long they remain under water depends on their level of activity.

And active sea turtle may remain under water for half an hour, and a sleeping sea turtle can remain underwater for up to seven hours.

The greatest threat to sea turtles is man.

Sea turtles drown when they get caught in fishing nets that prevent them from surfacing to get a breath of air.

Hatchlings get confused by bright lights when they emerge from their nests at night. They migrate toward the brightest lights around rather than toward the sea. In populated areas with bright lights along the shore, hatchlings move toward the lights and away from the sea where they die of dehydration or are eaten by predators.

Beach condominiums and houses in turtle nesting areas do not display lights at night that would confuse hatchlings. If there must be lighting on the beach, red and amber LED lights will not confuse the hatchlings on their short journey to the sea.

Plastics of all types are harmful to sea turtles. Sea turtles mistake floating plastic bags as jellyfish, and when they ingest the bags, they die from intestinal obstruction or suffocation.

Being a sea turtle is a risky business, and I might be a little grumpy if I faced the same challenges.

That’s why Grumpy Sea Turtles are the Third Wonder of Waterworld.

Dr. Dave

---