THE SEA TURTLES
- Friendly Fins
- Nov 18, 2024
- 6 min read
Updated: Mar 7
Why Learn About Sea Turtles
“Our elegance is known throughout the seas, we are always beautiful despite our age! We will know how to capture your gaze while we “fly” delicately near you!”
How to recognize sea turtles
There are currently 8 living species of sea turtles:
“We look a lot like our terrestrial cousins but we differ in some details! Discover them…”
They can reach considerable dimensions with differences from species to species: the largest is the leatherback turtle with about 2 meters and a weight of one ton.
Unlike their terrestrial relatives, they cannot retract their heads and limbs inside their shells.
They live almost always in water, except when laying eggs.
They breathe through their lungs, so they need to return to the surface to breathe.
Their fins are tapered and hydrodynamic, making them capable swimmers even if they do not reach high speeds (on average between 2 and 9 km/h). The front fins provide propulsion, while the rear fins act as a rudder to help them with direction.
Where sea turtles live
Sea turtles appeared at the time of the dinosaurs and have colonized all the tropical and temperate seas of the planet. They are not able to live in the cold, however, precisely because being cold-blooded animals they are unable to regulate their temperature and risk hypothermia; with the inability to swim and therefore the risk of dying.
Some, like the leatherback turtle, live in the open sea and rarely approach the coast (except for spawning), while others, like the hawksbill turtle, live their entire lives in the coral reef.
“Each of our 8 species has carved out its own space in the sea: some love to stay out in the open, some graze on the meadows of aquatic plants, some prefer the cool waters of the Mediterranean and some love the coral reef. Everyone has their own tastes after all!”
What do sea turtles eat?
Most sea turtles are omnivorous; only the green turtle is vegetarian, but only as an adult. In general, they feed on jellyfish, squid, shrimp, algae, sponges, corals and other vagile invertebrates on the seabed. However, each species has specialized in a specific diet based on the habitat in which it lives.
“We don’t have teeth, but rather a strong beak supported by powerful jaws, thanks to which we are able to break the shells and exoskeletons of our snacks!”
Sea turtle apnea
Sea turtles are skilled freedivers, able to stay underwater in search of food for a long time. When they rest, their metabolism slows down a lot and they can even bring their heart rate to one beat every 9 minutes, facing apneas of up to 5 hours.
"We often hide in caves or crevices to find some peace and take a nap!"
They are able to reach very great depths, over 300 m; the record is held by the leatherback turtle with a depth of one thousand meters.
The Senses of Sea Turtles
Sight:
Their eyes are well adapted to see both in and out of the water (on the surface of the sea or on the beach). They are also able to perceive bioluminescence, making them skilled hunters both at night and at depth.
Hearing:
Sea turtles are very good at sensing the vibrations of the water around them. They also seem to be able to hear low-frequency waves (thanks to a layer of fat in their ears similar to that of whales).
Touch:
Both the shell and the rest of the body of sea turtles are rich in mechanoreceptors that sense touch or pressure and transmit the information to the rest of the body.
Smell:
highly developed and functional for finding prey even in the dark.
“The sense of smell is also very useful for finding the beach where we were born and being able to lay our eggs, continuing the tradition!”
Magnetic sense:
The sea turtle is able to sense and use the Earth's magnetic field as a guide. Not only can they sense its intensity as it decreases from the poles to the equator, but they can also detect its inclination. Thanks to this, sea turtles have an accurate sense of their position, thus facilitating their migration over vast distances.
“This sense is an innate compass, very useful for not getting lost! In the open sea there are not many references and getting lost is very easy, trust me!”
Sea turtle migration
Sea turtles make very challenging migrations, even thousands of kilometers in the case of the leatherback turtle. They mainly migrate to search for food and to lay eggs.
Natal homing:
Sea turtles are known to lay their eggs on the same beach where they were born, but how do they find it again?
It is thought that there are two important factors at play:
Using the Earth's magnetic field to determine the position of themselves and the beach
Imprinting: that is, something they learned as soon as they were born and are able to recognize after many years, such as a certain characteristic of the beach, a particular scent, or the geographical coordinates of the beach where they saw the sea for the first time..
"The first factor determines the geographic location of the beach, while the second determines the specific beach! Simple after a migration of thousands of km, right?"!
But why choose that particular beach?
“Obviously because we are guaranteed to find favorable conditions for the birth and development of the little ones, after all, for us it all started from there, right?”
The life of sea turtles
Turtles can live very long, reaching 80 years of age.
They reach sexual maturity after 15-20 years of age.
Reproduction is very delicate and occurs in water by internal fertilization, after many weeks of courtship.
Males generally fertilize only one female during the breeding season.
“The males will live forever in the sea, while the females will return to dry land several times in their lives, to lay their eggs.”
The laying of eggs
The females return to the beach during the night and dig a hole about 80 cm deep,
where they will lay about a hundred eggs similar to ping pong balls.
“Moving onto the beach and digging a hole requires considerable effort, but we are still so scrupulous that after laying the eggs and covering the hole, we dig a “much more rudimentary and conspicuous dummy” to confuse predators as to the location of the real nest.”
The incubation of eggs varies from species to species between 45 and 70 days, also depending on humidity and temperature.
There is no parental care once the egg hatches, only the preparation of a perfect nursery.
The chicks take a few days to hatch from the egg and wait for the night with cooler temperatures to run into the sea attracted by the moonlight reflecting on the water.
Only about ten of the hundreds of eggs laid will become adult turtles.
Determining the sex of unborn children
The eggs take 2 months to mature and hatch, during these months the temperature of the nest is fundamental in determining the sex of the hatchlings:
Eggs developed in high temperatures will give rise to females
Eggs developed in colder temperatures will produce males.
Generally in a nest, the eggs that are more superficial will become female while those deeper will become male, this is true if there are no particular changes and fluctuations in temperature.
The Enemies of Sea Turtles
“Our life is not easy at all, we always have to watch out for many predators and manage to escape them, even before we hatch!”
Natural Enemies:
The eggs are subject to rainfall, beach erosion and predators.
As soon as the eggs hatch under the sand, the newly born turtles have to fight for their lives. More than 90% of them will never reach the sea, both the babies and the eggs are at risk of being eaten by foxes, crabs, lizards and sea birds.
At a young age they are at risk of being preyed upon by birds, sharks and large fish.
As adults, they may be eaten by killer whales, tiger sharks, sea lions and crocodiles.
The man
However, man remains the worst enemy of sea turtles:
Their nesting areas have been drastically reduced and fragmented, preventing them from laying eggs or hatching them.
But the problems don't end there: sea turtles are very sensitive to pollution, as they suffocate by ingesting rubbish or get caught in fishing nets.
Climate change, with the increase in temperatures, causes an imbalance in populations, as there will be more females than males.
Last but not least, it is still fished for its meat and its carapace, which is highly sought after by collectors.
“Each of our 8 species of sea turtles are in danger of extinction, which means we are disappearing from the Earth...
But Friendly fins could contribute to our salvation..”
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