Olive turtle description. The difficult journey of the olive turtles. Olive turtle nutrition
The offspring of six olive tortoises hatched in Rusikulia went to the sea. Rusikulya in the Indian state of Orissa is one of the main breeding grounds for these rare sea turtles.
According to forestry representatives, the mass hatching process is almost complete this year, the number of olive turtle egg layings has decreased compared to last year.
“About 61,000 turtles of various species laid their eggs on the coast in March of this year,” says S.S. Mishra, forestry officer of Berkhampur. For comparison, only three olive turtles laid eggs in Rusikulja in 2013.
Olive turtles travel thousands of miles to lay their eggs on the coast where they were born. Thus, the small numbers of these turtles that have arrived to breed indicate that either their population has declined significantly, or they no longer consider favorable conditions on one of their favorite coasts.
Protective Measures
Local forestry workers and volunteers from the village have made every effort to ensure maximum survival of the turtles.
Olive turtles hatch at night from eggs laid in the sand and immediately head out to sea. However, they are very sensitive to light, bright light sources can cause them to move in the wrong direction.
In order for the turtles to find their way into the sea, the local forestry department asked the municipalities to turn off street lights for several days during the mass hatching. Most of the local administrations agreed.
To prevent small turtles from going to land, special nets are stretched along the coast that delay them. They are then collected and released into the sea by local forestry workers and volunteers. This year, hatching started on March 10, which is quite early compared to previous seasons.
Newly hatched turtles, entering the water, swim against the current. During this process, they memorize the geomagnetic field of the Earth, which will allow them to return to their native places when the time comes for breeding. Turtles reach adulthood at 15-20 years of age.
The Indian state of Orissa has been a favorite breeding ground for olive turtles for centuries. However, the number of factors that threaten the survival of turtles is increasing every year.
In addition to predators, this species is threatened by natural factors such as high waves, heavy rains, strong winds, erosion of the beaches where they lay their eggs, as well as human factors - uncontrolled fishing and destructive human activities in coastal areas.
However, there is a tradition in Rusikulja to take care of these turtles, dating back to before scientists even noticed them. Fishermen and youth have been taking special measures for 20 years to protect the turtles. Sometimes they even tore apart their fishing nets to allow the turtles to feed. This is due to the fact that the locals revere these animals as one of the incarnations of the god Vishnu.
Ridley's Olive Sea Turtle - Lepidochelys olivacea- lives in the southern waters of the Atlantic, as well as in the tropical and subtropical regions of the Pacific and Indian oceans between 40 degrees north and south latitude. In North America, it is found in the waters of the Caribbean Sea and in the Gulf of California. The most famous turtle beach is located in the Bhitar Kanika Reserve in the Bay of Bengal (Orissa, India).
Ridley's olive turtle belongs to the large sea turtles weighing 45 kg and with a shell length of up to 55-75 cm, which is not considered large for sea turtles. The soft parts of the body are olive-gray in color. The head is narrow. The tail of the male protrudes from under the shell, while that of the female is under the shell. The thickness of the shell is relatively thin, has a heart-shaped outline, olive color. The paws have two claws. It is primarily a carnivorous turtle, feeding on invertebrates as well as jellyfish, snails, and crabs. It readily tries new foods, and plastic bags and other debris have been found in the stomachs of some turtles. In conditions of detention, they are prone to cannibalism, that is, eating their own kind. Turtles feed in shallow water on soft-bottomed shallows. It feeds on benthos in the absence of other food resources.
Although the exact age at which the turtle begins to produce offspring is not known, this does not occur until it reaches a length of 60 cm. Mating occurs on the beaches in spring and early summer in North America, and turtles do not adhere to monogamy. Sperm is stored in the female to fertilize the eggs throughout the season. Females return to the places where they were born, finding their way by smell. They lay their eggs at night in the first or last quarter of the moon. The clutch contains 300 or more eggs, but on average 107, which the female buries at a depth of 35 cm, after which she returns to the sea. The entire laying process takes the female less than an hour. The female can repeat such clutches monthly. The eggs resemble ping-pong balls and have an incubation period of 45-51 days, with ground temperature determining the sex of the young turtles.
Little is known about the social life of the Ridley tortoises, except that they migrate each year to the beaches to lay their eggs. At other times, the turtle feeds in the morning hours, and during the day it drifts on the surface of the water, exposing its shell to the sun's rays. At such a time, they can gather a lot in one place. This takes place in cool waters. When a turtle hits the warm water on a shallow, it doesn't need the sun to tan. In the event of a collision with a natural enemy (including humans), the turtle prefers to dive deep to escape pursuit. On land, turtles are threatened by possums, feral pigs, and snakes that hunt for eggs. Adult males, once on land, defend themselves by waving their front paws.
The Ridley tortoise spends almost all its life in coastal waters, not moving further than 15 km from it, preferring to feed on the shallows and lie in the sun. Recorded encounters with turtles in the open ocean.
Since the extraction of turtle eggs became legal in Costa Rica in 1987, local residents have sold 3 million eggs every season. This number included only eggs laid in the first 36 hours, since the next clutches destroyed the previous ones - approximately 27 million eggs.
Along with other sea turtles, the Ridley's olive turtle is considered a marine predator as fishermen often find them in their nets. Over the past 30 years, turtle populations have declined significantly as a result of hunting for females that come to the beach to lay their eggs, which serve as a source of meat and skin. The number of turtles is also limited by the space on which they can lay their eggs - worldwide, only five beaches are suitable for their purposes. The governments of some countries are preparing laws to protect or restrict the extraction of turtles, in the United States, the extraction of turtles is also limited.
Atlantic ridley turtle - Lepidochelys kempii lives in the Caribbean Sea, on the Atlantic coasts of France, Spain, England, in the southeast of Mexico (Yucatan), in the Gulf of Mexico, Colombia. The length of the shell is 70 cm, weight up to 45 kg. For a long time, these turtles were classified as loggerhead hybrids ( caretta) and bisses ( Eretmochelys) or green turtle ( Chelonia), but today it is considered a separate species.
Based on materials from the site http://animaldiversity.ummz.umich.edu/.
The olive turtle, also known as the olive ridley, is a medium-sized sea turtle, now under protection due to the threat of extinction due to extermination by humans and the influence of natural threats. She prefers tropical and subtropical waters of the seas and oceans, mainly the coastal part.
Description of the olive turtle
Appearance
The color of the shell - gray-olive - corresponds to the name of this species of turtles.. The color of newly hatched turtles is black, juveniles are dark gray. The shape of the carapace of turtles of this species resembles the shape of a heart, its front part is curved, and its length can reach 60 or even 70 centimeters. Along the lower edge of the shell of the olive turtle there are from four to six or more pairs of porous structure scutes on one side and the same number on the other side, about four in front, which is also a distinctive feature of this species of turtles.
It is interesting! Olive ridleys have flipper-like limbs, which they control perfectly in the water. The head of these turtles resembles the shape of a triangle when viewed from the front, the sides of the head are flattened. They can reach a body length of up to 80 centimeters, and a weight of up to 50 kilograms.
But males and females have differences by which they can be distinguished: males are more massive, unlike females, their jaws are larger, the plastron is concave, the tail is thicker and is visible from under the carapace. Females are inferior in size to males, and their tail is always hidden.
Behavior, lifestyle
The olive ridley, like all turtles, leads a calm measured mode of life, does not differ in constant activity and fussiness. Only in the morning she takes care of finding food for herself, and in the afternoon she calmly drifts on the surface of the water.. These turtles have developed a flocking instinct - straying into a large population, they retain heat so as not to be exposed to hypothermia in sea and ocean waters. They shy away from potential danger and are ready to avoid it at any moment.
Lifespan
On the life path of these reptiles, there are many dangers and threats that only the most adapted individuals can overcome. But those dexterous, hardy lucky ones may be given the opportunity to live a relatively long life - about 70 years.
Range, habitats
Ridley can be found both at the edge of the ocean and in its open spaces. But the coastal zones of the tropical latitudes of the Pacific and Indian Oceans, the coasts of South Africa, New Zealand or Australia from the south, as well as Japan, Micronesia and Saudi Arabia from the north, are its usual habitat.
It is interesting! In the Pacific Ocean, this type of turtle can be found from the Galapagos Islands to the coastal waters of California.
The Atlantic Ocean is not included in the territory of the olive turtle and is inhabited by its relative, the small Atlantic ridley, with the exception of the coastal waters of Venezuela, Guyana, Suriname, French Guiana and northern Brazil, as well as the Caribbean Sea, where the ridley can be found even near Puerto Rico. She also lives in deep oceanic and sea waters, where she can descend to a distance of up to 160 m.
Olive turtle nutrition
The olive turtle is omnivorous, but prefers food of animal origin. The usual diet of the olive ridley consists of small representatives of the marine and ocean fauna, which it catches in shallow water (mollusks, fish fry, and others). She does not disdain jellyfish, crabs. But she can readily eat algae or other plant foods, or even try new types of food, up to waste thrown into the water by humans.
Reproduction and offspring
When the turtle reaches a body size of 60 centimeters, we can talk about reaching sexual maturity. The mating season of Ridley starts differently for all representatives of this species, depending on the place of mating. The mating process itself takes place in the expanses of water, but baby turtles are born on land.
To do this, representatives of this species of turtles arrive on the coast of North America, India, Australia in order to lay eggs - they themselves were born here at one time and now strive to give life to their own offspring. It is surprising, however, that olive tortoises come to breed in the same place during their entire life cycle, and all together on the same day.
This feature is called “arribida”, this term is translated from Spanish as “coming”. It is also noteworthy that the turtle unmistakably determines the beach - the place of its birth - even if it has never been here since its birth.
It is interesting! There is an assumption that they are guided by the Earth's magnetic field; by another guess
The female olive ridley rakes the sand with her hind legs to a depth of approximately 35 centimeters and lays about 100 eggs there, then makes this place inconspicuous for predators, throwing sand and trampling it down. After that, considering her mission to reproduce offspring completed, she goes to the ocean, on her way back to her permanent habitat. The offspring at the same time becomes left to itself and the will of fate.
It is interesting! A fact that affects the fate of small turtles is the ambient temperature, the level of which will determine the sex of the future reptile: most male cubs are born in cold sand, and female ones in warm sand (more than 30 C 0).
In the future, after the incubation period of about 45-51 days, the olive turtle cubs themselves will have to hatch from the eggs and, guided only by the instinct inherent in them, get to the saving waters of the ocean - the natural habitat of these wonderful animals. Turtles do this under the cover of night, fearing predators.
They pierce the shell with a special egg tooth, and then make their way through the sand to the outside, rushing to the water. Both on land and in the ocean, many predators lie in wait for them, so olive turtles survive in very small numbers until adulthood, which prevents the rapid restoration of the population of this species.
Olive sea turtles are also called ridleys. The species is considered vulnerable due to a number of threats. You can most often meet representatives of the Ridley genus near the coastal part of the subtropical and tropical sea or ocean.
Description
The olive turtle can grow up to 70 cm in length. Her body weight does not exceed 45 kg. The shape of the shell is heart-shaped, the color is gray-olive. Turtles are born black, they brighten over time. They have a triangular head shape with shallow concavities. The anterior part of the carapace is curved upwards. Males differ from females in a more massive jaw, a depressed plastron and a thick tail.
Habitat
Comfortable places for olive ridley are the shores of the Indian and Pacific Oceans, South Australia, New Zealand, Micronesia, Japan and the northern regions of Saudi Arabia. Less common in the Caribbean and in Puerto Rico. In water, the animal can dive to a depth of no more than 160 m.
and food
The behavior of olive turtles is characterized by constant calmness. In the morning they are in search of food, and the rest of the day is spent in measured swimming on the surface of the water. They prefer to be in the company of their own kind all the time. From the sharp cooling of the water, they are saved by the fact that they huddle into a large livestock, thereby retaining heat. In moments of imminent danger, they prefer to avoid it in any way. On land, their lives are threatened by wild pigs, opossums and snakes that ruin the masonry.
The olive turtle can be called an omnivore, but more often it prefers animal food. Its usual diet includes various invertebrates (shrimp, crabs, snails and jellyfish). It also feeds on algae. Sometimes swallows inedible objects, including garbage thrown out by people (fragments of plastic bags, polystyrene, etc.). While in captivity, it can eat members of its own species.
reproduction
Every spring or early summer (the onset of the mating season depends on the place of mating), an adult olive turtle, the photo of which is presented below, returns to the beach where it first saw the light, to continue its kind. Moreover, the place of reproduction throughout the life cycle remains unchanged. This phenomenon was called "arribida" (Spanish for "coming"). Turtles determine the place of their birth accurately, despite the fact that they can experience the period of growing up in other territories. According to biologists, olive ridleys use the Earth's magnetic field as a guide.
An animal is considered sexually mature when its body length is at least 60 cm. Mating of the male and female takes place in the water, and the eggs are laid on land. First, a female individual rakes a hole about 35 cm deep with her hind legs. Then the female lays about a hundred eggs, after which she backfills it with sand and tramples it, thereby making the place inconspicuous for natural enemies. This completes the turtle's maternal mission - it returns to the lands of its permanent residence. The offspring is left to itself or to chance.
Temperature is the main factor influencing the sex of a reptile. In a cold environment, males are formed, and in a warm environment (more than 30 degrees Celsius) - females. The incubation period lasts about 45-50 days. At the end of this period, the hatched turtles get to sea or ocean water. They do this exclusively at night, thereby reducing the risk of collision with predators. A special egg tooth allows turtles to deftly break through the shell.
population
In the water and on land there are many creatures that strive to feast on olive ridleys. The embryos are eaten by coyotes, crows, dogs, vultures, and others. Hatched young turtles are fed by the above predators, as well as frigatebirds and snakes. In the sea and ocean, sharks are the main danger. Most turtles do not have time to live to puberty, which is why the number of individuals is rapidly declining.
There are other reasons why the species is listed in the Red Book. The olive turtle is a constant victim of illegal capture. For poachers, both adults and egg embryos are valuable. Further, ridleys end up in the kitchens of trendy restaurants, among whose visitors dishes from turtle meat are in demand.
The number of broods also depends on the environmental factor and natural disasters. Garbage drifting in the world's oceans, a curious turtle loves to swallow, thereby causing irreparable harm to his body. Reptiles often get caught in fishing nets. This threatens animals with rapid death. Recently, however, fishermen have been using modern nets in which it is impossible for a large turtle to get entangled.
Many residents of India and Mexico, both on a voluntary basis and at the state level, use the incubation method, after which they release the born olive turtles into the long-awaited expanse of water. As for life expectancy, the age of the most dexterous individuals can reach 70 years.