THE AMAZING STORY OF HOW SEA #TURTLES MATE AND REPRODUCE. #OMAN
Updated: Jul 3, 2019
The beaches of Oman that open onto the Indian Ocean, are a popular and preferred nesting place for giant turtles.
The turtle of story, a female, has waited for years, swimming for miles and miles in the depths of the sea. No one knows exactly where she has been throughout her juvenile life, only when she has reached adulthood has her large teardrop-shaped carapace been spotted along the coral reefs and shallow lagoons of the coast.
She spent most of her life in immersion, emerging every 4-5 minutes to return the oxygen in the lungs with a single explosive exhalation and a rapid inhalation. At night, while sleeping, she wedged herself under the protrusions of rocks and reefs to escape potential predators, preferring to return to the same place night after night.
Finally, at about 35 years of age, half of the course of her life, having reached a weight of between 68 and 190 kilos and a length of up to 1.5 meters, comes the most important moment of her existence: the reproductive phase.
Swimming in the open ocean, she relied on the direction of the waves, sunlight and temperatures. The spherical lenses of her eyes are suitable for underwater refraction, but offer a short-sighted vision when out of the water. The success of the reproduction is too important to be dependent on its imperfect sense of sight. It needs a sandy beach, easy access to the ocean for the young, a temperature suitable for incubating eggs and a low presence of predators.
She has spent a lot of energy, swimming for many miles through the ocean waves to return to the place where she was born: the beach that has guaranteed the reproductive success of many generations. The ability to return to the native beach is due to an internal compass that allows to detect the magnetic information using forces acting on the crystals of the brain. Through these crystals, she was able to perceive and recognize the intensity of the Earth's magnetic field and return to her original beach for nesting. The ability to return to the place of origin is called "homing natal" and is common to many other species, including salmon.
Males also return to their native beach once they have reached sexual maturity, as they are certain to find the females with which to mate.
The mating takes place a few meters from the shore, after having scrutinized the coast through the darkness of the night in search of the revealing movement of predators, leaves its natural element to venture laboriously on the beach. Like a ferryman of souls, he moves from one world to another to pursue the alternation of life. With the front fins he creates a depression in the sand that contains all the carapace and protects it during the time necessary for laying the eggs, about an hour, an hour and a half. The powerful front fins sweep away the sand that splashes all around and the eyes release a watery secretion for protection. Then, with the back fins, she digs a narrow hole, 30-40 cm deep, where she drops, one by one, 100-200 eggs. She breathes noisily to return the oxygen she needs to compensate for the heavy stress and the watery drops falling from her eyes look like tears. At this moment she is so concentrated in carrying out her mission that she resists to exhaustion.
The eggs are round, have a diameter of about 4.5 cm, the shell is soft and opalescent white. She drops them one on top of the other and then, before going back into the water and resting, she carefully covers the hole she dug. She will do this up to five times each season, laying a total of between 400 and 1000 eggs. The time of hatching of the eggs and the genus of the young are determined by the incubation temperature of the nest. Hot nesting sites above 30 degrees Celsius favor the development of females, while colder ones produce males. Also, the position of the egg in the nest influences the determination of the genus: the eggs in the middle of the nest tend to generate females because of the warmer conditions inside.
After about 50-70 days the eggs hatch and the young come out, all together, from the nest to head quickly to the sea. This is the most dangerous moment in the turtle's life: crabs, gulls and foxes wait for the small turtles with their tender carapace to feast. Another great danger for small turtles is the increasing urbanization and light pollution that comes with it. As instinct leads them to go towards the light, if they confuse electric lighting for the reverberation of the sea, they end up between the houses instead of the waves prolonging exposure to predators or dying exhausted and dehydrated.
It is estimated that only 1% of the young reach the ocean, where the occasional predators are only the large tiger sharks. The main danger to turtles remains the human being.
Five species of turtles visit the waters and beaches of Oman: the giant green turtle Chelonia Midas; the Caretta Caretta, also present in the Mediterranean; the hawksbill turtle; the olive-green turtle and the lute turtle.
The main nesting sites are along the beaches of the island of Masirah, the islands Daymaniyat and Ra's al Hadd, where the Ministry of Environment of the Sultanate of Oman has dedicated a protected area and a research center to turtles.