Sea turtle — an amphibious reptile belonging to the family Testudines turtles, and the subfamily Cheloniidae (Sea Turtle) this family includes 4 species: olive turtle, loggerhead, hawksbill, green turtle, Australian green turtle, Atlantic ridley. Previously, this species included the leatherback turtle, but now it belongs to the subfamily Dermochelys.
These animals live in the seas and oceans all over the world, they cannot be found only in the cold Arctic waters. Sea turtles are fast swimmers and can dive deep in search of prey.
Origin of the species and description
Photo: Sea Turtle
Sea turtles are chordates belonging to the class of reptiles of the order of turtles, the superfamily Chelonioidea (Sea turtles). Turtles are very ancient animals. The ancestors of modern turtles lived on our planet about 220 million years ago.
The ancestors of these amazing animals are the ancient animals cotilosaurs that lived in the Permian period of the Paleozoic. Kotilosaurs looked like large lizards with wide ribs that formed a kind of shield. According to another theory, the ancestors of turtles were the ancient amphibian discosauris.
Video: Sea turtle
The oldest turtle known to science today, Odontochelys semitestacea, lived 220 million years ago during the Mesozoic era. This turtle was a little different from modern turtles, it had only the lower part of the shell formed, it still had sharp teeth. More similar to modern turtles was the tortoise Proganochelys quenstedti, which lived about 215 million years ago. This turtle had a strong shell that covered the chest and back of the animal, and there were still teeth in the mouth.
Modern sea turtles are rather large animals. The shell of sea turtles is oval or heart-shaped, covered with horny shields. Unlike land turtles, sea turtles cannot tuck their heads into their shells due to their short, thick necks. The lower limbs are flippers, and the front flippers are larger than the hind ones.
Almost all their lives, sea turtles lead an underwater lifestyle, and come to land only to create clutch and lay eggs. When born, turtles return to the water driven by instinct.
Appearance and Features
Photo: What a sea turtle looks like
Almost all sea turtles have a similar structure. Sea turtles have a large, streamlined shell that covers the turtle’s back and chest. The head is large, not retracted under the shell. The lower limbs are turned into flippers. The front pair of limbs is usually larger than the hind ones and more developed.
The fingers on the limbs are fused into flippers, and only a few fingers of the hind legs have claws. The pelvic bones in sea turtles are not crossed with the pelvis. Due to their structural features, sea turtles move very slowly on the ground, but they are excellent swimmers. The superfamily Cheloniidea includes 4 species of turtles. Depending on the species, the appearance of turtles is different.
Chelónia mýdas green turtle is a very large turtle. The length of the shell is from 85 to 155 cm, the weight of an adult sometimes reaches 205 kg. In very rare cases, the length of the shell can reach 200 cm, and the turtle can weigh up to half a ton. The color of turtles of this species is olive or brown with white and yellow spots.
Eretmochelys imbricata (Bissa) is similar to, but much smaller than, green turtles. The body of an adult turtle is about 65-95 cm long. The body weight is about 40-60 kg. The shell of turtles of this species is covered with a layer of horny shields. The shields are tiled adjacent to each other. Heart-shaped shell. The back of the shell is pointed. And also turtles of this species have a strong beak. The color of the shell is brown. You can see the yellow spotted pattern.
Lepidochelys kempii The Atlantic ridley is the smallest turtle of this family. The size of an adult is 77 cm, body weight is 47 kg. This species has an elongated triangular head. The color of the carapace is dark gray. This species has sexual dimorphism in favor of females.
Caretta caretta Loggerhead. This type of turtle has 2 claws on its flippers. The shell is heart-shaped, from 0.8 to 1.2 m long, gray-green in color. The weight of an adult is 100-160 kg. Females are also larger than males. There are 10 costal scutes on the back of a turtle. The large head of the animal is also covered with shields.
Lepidochelys olivacea green ridley is a medium-sized turtle with a shell length of 55-70 cm. The body weight of an adult is about 40-45 kg. The shell is heart-shaped. The carapace has four pairs of porous scutes on the underside of the carapace and about 9 scutes on the sides. The shell is flattened from above, the front part is slightly curved upwards.
All sea turtles have excellent eyesight and can distinguish colors. Sea turtles have eyes on the top of their heads, while land turtles have eyes on the sides of their heads.
Fun fact: A turtle’s shell is so strong that it can withstand 200 times its weight. reptiles.
Where does the sea turtle live?
Photo: Sea turtle in water
Sea turtles can be found in oceans and seas around the world. These animals are not only found in the cold Arctic waters. Green turtles inhabit the tropical regions of the world’s oceans. Most of these animals can be found in the Pacific and Atlantic oceans. Byss turtles choose places with a temperate climate for life. They live in the waters of the Black Sea and the Sea of Japan in the area of Nova Scotia and Great Britain.
And also these animals can be found in southern Africa, in the waters of New Zealand and Tasmania. The hawksbill tortoises are capable of long-distance migrations, and they make them during the breeding season. Turtles of this species nest on the shores of Sri Lanka and the Caribbean Sea.
May nest on the shores of Turkey. The Atlantic ridley inhabits the Gulf of Mexico. These animals can be found in southern Florida, Great Britain, Bermuda on the coasts of Belgium, Cameroon and Morocco. Usually lives near the coast in shallow water, however, while hunting, it can dive to a depth of 410 meters and stay under water without oxygen for up to 4 hours.
Turtles of the Loggerhead species live in the waters of the Pacific, Atlantic and Indian oceans. They live in places with a temperate climate. For nesting, they make long migrations to places with a warm tropical climate. Usually for nesting they sail to the island of Maskira in Oman.
And nesting sites in Australia and the Dominican Republic are also known. Olive turtles prefer the waters of the Indian and Pacific Oceans. Sea turtles spend their entire lives in the water, only females come ashore to lay their eggs. After the formation of the clutch, the turtles immediately go back into the water.
What does a sea turtle eat?
Photo: Large sea turtle
Most sea turtles dangerous predators.
The diet of sea turtles includes:
- algae;
- plankton;
- crustaceans;
- mollusks;
- fish;
- snails;
- shrimp and crabs.
Interesting fact: Green turtles are predators only in the first years of their lives, with age they switch to plant foods.
Sea turtles hunt for differently. Most of them wait for their prey in algae for a long time, then attack sharply. Some turtles use their tongue as bait, displaying it and waiting for the fish to swim up to grab it.
Sea turtles are able to swim quickly and dive to great depths for prey. Sea turtles have been known to attack some waterfowl, but this is rare. Among some species of turtles, cases of cannibalism were noted, large turtles attack juveniles and turtles of small sizes.
Small sea turtles are often kept as pets. In captivity, the sea turtle is fed meat and various offal, chicken, insects, fish, mollusks and crustaceans. It is also necessary to ensure that there is a lot of vegetation in the aquarium. Turtles are very fond of eating algae.
small pieces, removing the bones. Once a month they give additional vitamin and mineral supplements, chalk, eggshell powder.
Peculiarities of character and lifestyle
Photo: Leatherback Turtle
Sea turtles have calm character. They are leisurely, although they are able to swim quite quickly and well. The whole life of sea turtles takes place in the water. Turtles stay in shallow water near the coast, however, while hunting, they can dive deep into the water and stay there for a long time.
All sea turtles make long-distance migrations in order to acquire offspring. No matter how far the turtles are from the warm tropical shores where they themselves once were born, when the time comes, they return there to lay their eggs. In this case, one turtle always forms a clutch in the same place. Turtles breed at the same time and hundreds of females can be seen on the shores during the breeding season.
The social environment of sea turtles is undeveloped. Turtles most often live alone. Young turtles, hiding from predators, spend almost all the time in thickets of algae, where they can feel safe. Older turtles swim freely in the water. Sometimes sea turtles like to bask in the sun by climbing on the rocks.
Under poor environmental conditions, and lack of food, sea turtles are able to fall into some kind of suspended animation. At this time, the turtles become lethargic, they eat little. This helps the turtles survive during the winter. In winter, turtles sink to the bottom, can live anaerobically for a long time without coming to the surface.
Social structure and reproduction
Photo: Sea turtle in the sea
Sea turtles breed in warm tropical waters. Mating takes place in shallow water next to the sandy shore. Males choose a female and swim right up to her muzzle. If the female is ready and does not reject the partner, mating takes place, which lasts several hours. Males do not show aggression towards females, females, on the contrary, can bite an unwanted boyfriend.
After mating, the female comes ashore and lays her eggs. The female forms a clutch by digging a deep hole in the sand. At the same time, masonry can be located in the most unexpected places in the middle of the beach, or on the side of the road. The female makes a deep recess in the sand up to half a meter deep. The female lays her eggs in the hole. In one clutch there are about 160-200 eggs. After the formation of the clutch, the female leaves the clutch and never returns to it. Parents are not interested in the fate of offspring.
An interesting fact: The sex of the future offspring depends on the temperature of the sand in which the eggs are buried. If the sand is warm, females will hatch, if temperatures are cold, males will hatch.
A few months later, tiny turtles are born. When the time comes for babies to be born, they break the egg shell with an egg tooth, and get out to the surface. Little turtles instinctively crawl towards the sea. However, a lot of predators are waiting for the cubs on the shore, so not everyone gets to the water far. In the water, small turtles are forced to lead a secretive lifestyle for a long time, hiding in thickets of algae from predators. Turtles become sexually mature at about 30 years old.
Natural enemies of sea turtles
Photo: Green Sea Turtle
Despite the natural means of protection of turtles – a strong shell, sea turtles are very vulnerable creatures. Most sea turtles die in early childhood and the mortality rate at this stage is about 90%.
The natural enemies of sea turtles are:
- large sharks;
- fish;
- dogs;
- raccoons;
- gulls and other birds;
- crabs.
Only sharks are dangerous to adult turtles. Masonry can be destroyed by many predators; on land and in water, juveniles can be attacked by birds, dogs, and predatory fish. During bad weather conditions in turtle breeding areas, many hatchlings often die. They either do not hatch at all due to too low, or vice versa, high sand temperatures, or die already hatched and hit the shore in bad weather.
But the main enemy for sea turtles is man. People catch sea turtles as the meat of these animals is used as food, and the shell is used to make jewelry, jewelry boxes and many interior items.
Water pollution has a very negative effect on the population of sea turtles. Often, sea turtles perceive garbage and polyethylene and pieces of plastic as edible jellyfish and die due to ingestion of inedible objects. Many turtles become entangled in fishing and shrimp nets and die as a result.
Interesting fact: Some species of turtles eat poisonous shellfish as self-defense, while this does not harm the turtles themselves, but the turtle meat becomes poisonous and this scares off predators.
Population and species status
Photo: What a sea turtle looks like
It is extremely difficult to track the population of sea turtles due to the fact that turtle populations are too scattered and turtles make long-distance migrations. However, it is known that due to human activities, the population of sea turtles has been greatly reduced. First of all, the decline in the population of sea turtles is caused by the ruthless hunting of these creatures in order to obtain meat and valuable shell.
Also, the arrival of civilization and the development of beaches in turtle breeding grounds had a negative impact on the population of sea turtles. Many turtles are afraid of noise, electric lights and a lot of people on the beach and simply do not come ashore to form clutches. Many turtles are killed by being caught in fishing nets and swallowing debris floating in the water.
At the moment, most species of sea turtles are listed in the Red Book as endangered species, and the species are especially vulnerable. The hawksbill tortoises are almost completely exterminated, so hunting for them is prohibited all over the world. However, there are black markets where poachers trade turtle eggs and turtles of this species and the demand for them does not weaken. Measures are being taken around the world to protect rare species of turtles in order to restore their populations.
Sea turtle conservation
Photo: Red Book Sea Turtle
Many sea turtles are listed in the Red Book and need special protection measures. Now catching hawksbill turtles is prohibited. In many countries, trade in turtle shells, their eggs and meat is prohibited. The authorities of the Dominican Republic make daily raids to identify violators selling products from these animals.
In the Dominican Republic, a society for the protection of turtles was also created. They protect the beaches where these animals breed. In order not to scare off the females that go to the beach to form clutches, all the lighting on the beach is red. Any noise during the mating season of turtles is prohibited.
Beaches where turtles breed during the mating season are closed to tourists. The clutches are marked with flags, in some countries zoologists carefully collect the eggs and take them to the nursery, and there the eggs are placed in an incubator. Hatched turtles grow in captivity for up to 2 months, and then released into the sea. Also, special GPS sensors are glued to each turtle to track the movement of the animal. In many countries, the export of turtles of rare species is prohibited.
In order for fewer animals to die in fishing nets, fishing nets have been modernized by order of the authorities. Thanks to this modernization, tens of thousands of rare species of turtles were saved. However, every year, despite the modernization, up to 5 thousand turtles per year die in the nets. Most often, turtles are caught in the nets in the Sea Bay, where they are engaged in catching shrimp. Rescuers catch turtles that are entangled in nets or poisoned by garbage and try to help them.
The sea turtle is a very amazing, ancient creature, which is also very hardy. They are true survivors. However, due to human activities, the population of these animals is on the verge of extinction. Let’s take care of our nature in order to save these amazing creatures. We will monitor the cleanliness of reservoirs and protect nature.
