Sea turtles are one of the best known animals that inhabit seas and oceans and even so, most of us are still very curious. In fact, scientists continue to discover and learn many new things about them every day.
In this article by EcologíaVerde and the CRAM Foundation (Center for the Recovery of Marine Animals), we focus on explaining what the reproduction of sea turtles is like . Do all of your species lay eggs? And how do they put them? How is your courtship? What is the breeding season for sea turtles? In this fascinating article you can find the answers to these and other questions related to the issue of how sea turtles reproduce .
How is the reproduction of sea turtles
The type of reproduction of sea turtles is sexual and oviparous, that is, these animals that inhabit oceans and seas are oviparous animals , since they lay eggs from which the young are later born. Neither species is ovoviviparous nor is it viviparous.
The female sea turtles , after mating with the males, go to the beaches, make their nests and lay the eggs , through their oviduct, to cover the nests when they finish and abandon them. After an incubation time, when the formation of the young is complete, they are born breaking the shell, making their way through the sand of the nest and moving directly towards the sea.
How is the courtship of sea turtles
Courtship and sexual interactions between sea turtles continue to hold many mysteries for scientists who study them. However, some details are known, such as the following:
- The courtship of sea turtles occurs in breeding areas, which are usually near the coast .
- Some general behaviors have been observed among the different species of these marine reptiles that are related to the courtship season .
- Examples of these behaviors are the biting of the males on the fins of the females and the harassment of different males to the same female to try to reproduce with her.
Sea turtles always mate in the water , in courtship areas close to coasts and beaches. After courtship, when the female accepts the male, they mate. In the mating of sea turtles , if the female does not flee and accept the male, he will mount on the back of the female’s carapace, clinging to the top with the nails of his front flippers. Then, when the male is already well attached to the female, internal fertilization occurs .
One aspect to highlight regarding the mating of sea turtles is that in many cases females can mate with more than one male . Therefore, each egg laying or nest of a female can be fertilized by the sperm of different males.
Only the females reach the shore and come out to the beach every time they go to make their nests to lay their eggs. Males almost never return to land once they leave the sand of the beach where they are born.
Another question related to how sea turtles reproduce is at what age do they begin to do so, that is, when they reach sexual maturity in order to reproduce.
These marine reptiles reach sexual maturity in their mid-30s , but it depends on the species . The green turtle, for example, can take up to 50 years to reach sexual maturity, but it can occur between 17 and 50 years.
The breeding season of sea turtles can vary between species, even within the same species we can find turtles that reproduce at different times .
For example, in the case of the leatherback or leatherback turtle, reproduction is seasonal and coincides with the humid and warm weather of the place where it nests. In the tropical areas of America it breeds between February and July and on the Atlantic coasts of Africa between November and March. On the other hand, the loggerhead or loggerhead turtle has a more homogeneous pattern and usually reproduces in early spring in the different breeding areas of the species.
The nest and laying of eggs of sea turtles
The behavior of sea turtles regarding nesting is still being studied today. Although it is true that most sea turtles present philopatry (that they return to nest on the beaches where they were born ), there are exceptions. The leatherback turtle, for example, has less fidelity to return to the laying beaches and, at times, can nest in different places hundreds of kilometers apart.
It is believed that many turtles choose the nesting beach based on the underwater topography of the place, the type of sand and its texture, the external vegetation, the rock formations, etc. Even so, it is not absolutely certain what the reasons for selecting these beaches are.
When the time comes for the sea turtles to lay eggs , the females arrive at the beach they select, which in some species happens individually or in a few females at one time and in other species it happens in arrivals, it is say, in bulk, and they start with the following process:
- They choose a place, even some species tend to nest in the same place on the beach every time they go.
- To make the nest they use their front and rear fins to move the sand away until they form a hole of the right size.
- As soon as they consider that the nest is ready, they begin to lay the eggs, with their oviduct, which all remain together in the hole.
- When finished, they begin to cover the nest with the sand that they had previously removed, helping themselves again with their fins, especially the rear ones.
- When they see that the nest is completely covered, they return to the sea and no longer see the nest or monitor how the young are or when they are born. This whole process is exhausting for the females , since out of the water they feel less secure, they move slower and make a huge effort, both to reach a dry area of the sand and prepare the nest and to lay the eggs and then cover them well.
There are always enough eggs in a sea turtle nest, but how many eggs do sea turtles lay? Regarding the average number of eggs that the females lay in each nest , we can only indicate that it is something difficult to say because within the same species we find a lot of difference between nests. However, trends for some species are as follows:
- Loggerhead or loggerhead turtle : they lay between 100 and 125 eggs (Florida) and between 65 and 95 (Cape Verde and Mediterranean), but nests of around 30 eggs have been found occasionally.
- Green turtle: between 110 and 130 eggs.
- Leatherback or leatherback turtle : between 80 and 90 eggs.
The incubation of the eggs in the nests of sea turtles takes place over 60 days , although this period may vary according to various factors such as temperature, and it will be the moment when the hatchlings will be ready to leave the sand and go straight to the sea.
One of the curiosities of sea turtles is that the sex of the turtles is determined by the incubation temperature of the nest . If the temperature is close to 29.5 ºC, similar percentages of females and males can emerge. If the temperature exceeds 29.5 ºC there will be a higher percentage of females and if the temperature is lower there will be a higher percentage of males.
Watching sea turtles hatch can be an amazing sight, but we must remember that, if this happens to us or if we find a nest in which the eggs have not yet hatched, we must never take the eggs or the small turtles (not even to take photos or take them to the water). To avoid harming these animals, if it is really necessary and important for the conservation of the species to move the eggs from the site, catch the turtles to move them to the water or other related actions, the professional people who study these will have to be commissioned. animals. Therefore, in these situations, in the case of Spain, you must first call 112 and from there give the emergency notice to the foundation or association in charge of helpingconserve marine life in the area, such as the CRAM Foundation (Center for the Recovery of Marine Animals).
In this foundation, among other actions, they are in charge of taking care of each sea turtle nest that they detect in the area in which they operate, as well as making sure that all possible turtles are born and reach the sea. Sometimes even a few are left for study and care in a suitable environment and, after a while, they are released completely healthy. In this way, they help to ensure that a part of the population of the new generation born in this area reaches an age when it has fewer predators and, therefore, it is easier for these turtles to survive and reproduce to continue increasing their population. If you are interested in knowing better and helping the CRAM FoundationWe invite you to enter this link where you will learn in detail the ways to collaborate with them: from € 1 per month to donations of the amount you want or even to volunteer at their recovery center.