OLIVE RIDLEY TURTLE: CHARACTERISTICS, HABITAT, CONSERVATION, FEEDING - BIOLOGY - 2025

The olive ridley sea ​​turtle (Lepidochelys olivacea) is a reptile with aquatic habits, which goes to land only to lay its eggs. This species belongs to the Cheloniidae family, and is characterized by the greenish appearance of its shell. This color fades towards the ventral area, which is yellowish.

This sea turtle cannot retract its head into the shell. However, it has adaptations that allow it to protect itself from predators. Among these is its cuirass, formed by costal and vertebral shields. Also, it has thick, scaly skin that covers its head, neck, and limbs.

Olive ridley turtle. Source: Brad Flickinger

Although the male and female have a similar size in body, it differs by having a longer tail. Also, the male has 2 strong and large claws on the front limbs. These allow him to hold the female tightly during copulation.

The Lepidochelys olivácea is distributed in tropical and subtropical waters worldwide. Thus, it is abundant in the Pacific, Indian and Atlantic oceans, except for the Caribbean Sea. In relation to nesting areas, they are found in tropical waters, especially in Panama, Costa Rica, Nicaragua and India.

characteristics

Eder Omar Campos González

Size

The olive tortoise, as this species is also known, can weigh up to 45 kilograms. However, species of 50 kilograms have been found. The length of the body is approximately 75 centimeters.

Coloration

The skin has a grayish hue. Their shell is olive green to grayish-green in color, but may appear reddish, due to the algae that usually grow on it. As for the plastron, it is whitish or greenish-yellow.

Body

The head is large, broad and triangular in shape. The concave sides of this are most evident in the upper area of ​​the muzzle. As for its front limbs, they are paddle-shaped, each with two claws.

Shell

The carapace is thin and heart-shaped. It is flattened dorsally and has four pairs of inframarginal scutes, with pores on the bridge. In the prefrontal area it has two pairs of shields and 5 to 9 costal shields on each side. The first of these is in contact with the neck.

Variations

This species is unique in terms of the variability of the number of vertebral or back scutes and of the sacks, also called ventral.

Some Lepidochelys olivácea only have 5 pairs of ventral scutes, which could be divided. In this way, 6 to 9 asymmetric shields are created. According to the researchers, these species are most abundant in the eastern Pacific Ocean.

Another variation, attributed to geography, is coloring. Thus, the olive ridley turtles that inhabit the eastern Atlantic have a lighter tone than the rest of their genus. On the other hand, those that live in the eastern Pacific tend to have a slightly taller carapace than the rest of the sister species.

Likewise, the size can also vary. In this sense, the carapace of the females found in Suriname measures between 62 and 74 centimeters. Those that live in Honduras have a cuirass 58 to 74 centimeters in length, while in those of Mexico, the length is 56 to 78 centimeters.

Young

The hatchlings have a dark gray carapace, bordered by a white line. This measures 37 to 50 millimeters. Both newborns and juveniles have serrated posterior marginal scutes, which in adulthood become smooth.

The young have 3 dorsal keels, the central one gives them a toothed profile. This aspect remains until the animal reaches sexual maturity.

Sexual dimorphism

Sexual dimorphism is evidenced in adults of this species. Thus, mature males have thicker and longer tails. Also, on the front limbs, the claws are enlarged and curved. This allows him to firmly hold the female shell during copulation.

The male's carapace is longer than that of the female. Also, it has a concave and smooth plastron, probably as an anatomical adaptation for mating.

Breathing

The olive ridley turtle spends most of the day submerged in water, but must surface to breathe air. With a single exhale and a quick inhale, this marine animal can fill its lungs with oxygenated air.

In relation to the lungs, this organ has adaptations that allow it to carry out gas exchange in a very short time. In this way, gases are not trapped during dives.

As for the ability to hold your breath, it is affected by stress. Because of this, when olive ridley turtles become entangled in shrimp trawls, they can drown in a few minutes.

Taxonomy

-Animalia Kingdom.

-Subreino: Bilateria.

-Filum: Chordata.

-Subfilum: Vertebrata.

-Superclass: Tetrapoda.

-Class: Reptilia.

-Order: Testudine

-Suborder: Cryptodira.

-Superfamily: Chelonioidea.

-Family: Cheloniidae.

-Subfamily: Carettinae.

-Gender: Lepidochelys.

-Species: Lepidochelys olivácea.

Habitat and distribution

Eder Omar Campos González

The Lepidochelys olivácea has a circumtropical distribution. Thus, they are found in subtropical and tropical waters of the Indian, Atlantic and Pacific oceans. Regarding nesting, they occur in tropical waters.

Migratory circuits take place in some subtropical and tropical areas. Thus, in the Atlantic Ocean, they include the central east, southeast, northwest, southwest and central west areas. In the Indian Ocean, they occur in the eastern and western areas.

In relation to the Pacific Ocean, the migratory routes cover the central east, southwest, northwest and central west regions.

Habitat

Within the same region, the olive ridley turtle can move between the neritic and oceanic zones or it could occupy only the neritic waters. To date, it is unknown if this species moves between different ocean basins or if it usually crosses one oceanic border to another.

Like the vast majority of sea turtles, Lepidochelys olivacea shows a complex life cycle. Because of this, it requires a diversity of locations, geographically separated, and various habitats.

The females nest on coastal beaches, where the newborn hatchlings head to the marine waters to continue their development. These remain in a pelagic phase, while currents disperse them far from their native place.

When they reach sexual maturity, the male and female migrate towards the shores, concentrating near the nesting beaches. However, some males may remain in ocean waters and mate en route to the breeding ground.

The nesting site where the largest number of female olive ridley turtles are concentrated is Gahirmatha Beach in India. There, around 800,000 females lay their eggs, for approximately 7 or 8 consecutive nights.

Migrations

Some adults of Lepidochelys olivacea are usually residents of coastal regions, occupying an area between 138 and 120 km2. On the contrary, others are migratory. When they travel, they travel up to 83 kilometers per day, using the main ocean currents for this.

This species regularly migrates between feeding and reproductive areas. This is due to the fact that the places where food sources abound are far from the nesting beaches.

On Nancite beach, in Costa Rica, the researchers conducted a study on the nesting performed there by females of this species. The results indicate that olive ridley turtles did not form groups during foraging, or during migration back to the feeding area.

For this reason, experts suggest that the groups of this species are formed by several turtles that use the same habitat simultaneously.

Post-breeding migrations of Lepidochelys olivacea are complex. The routes usually vary annually and there are no apparent migration corridors.

State of conservation

Eder Omar Campos González

Olive ridley turtle populations have decreased between 31 and 36% in the last 3 generations. This situation may be associated with its slow growth rate, in combination with the impact of various anthropogenic factors.

This has led the IUCN to categorize this species as a reptile vulnerable to extinction.

- Threats

Degradation of foraging areas

Some of the feeding grounds of Lepidochelys olivacea are contaminated. This occurs due to the use of pesticides and solvents, wastewater and industrial discharges.

These pollutants influence the benthic zone of the oceans, negatively affecting the productivity of the species that inhabit there. As a consequence, the abundance of prey that make up the olive ridley's diet decreases.

Another factor that affects the population decline is the construction of piers and marinas near the coast. These facilities imply an increase in shipping vessels, and therefore a greater release of pollutants into the water.

Hunting

In the eastern Pacific waters, illegal hunting of Lepidochelys olivacea occurs widely. This brings a high level of impact on the populations of said reptile. In the West Atlantic, catches have declined markedly, while in the Indian Ocean, this illegal activity continues to be widespread.

Also, the olive ridley turtle is caught incidentally, due to its entanglement in trawl nets, gillnets and longlines. The use of shrimp trawling in the western Atlantic is one of the main threats to this species.

In those nesting beaches that are in remote regions, where there is no protection from the olive ridley turtle, the extraction of the eggs is almost 100%.

These can be destined to satisfy the nutritional needs of the populations surrounding the bay, or they could be commercialized in local and national markets.

- Actions

Lepidochelys olivacea is listed under appendix I of CITES, so its commercialization is regulated. In addition, the laws of the countries that are part of the distribution of this species, confer protection.

However, the implementation of some of these laws has been carried out ineffectively. Successful actions have generally been based on excellent coordination of national programs. These are accompanied by joint work with various local and non-governmental organizations.

Lifecycle

Claudio Giovenzana

The olive ridley sea turtle is sexually mature between 13 and 16 years of age. From that stage on, it meets for several months in colonies of young. These areas are located in shallow waters, 2 or 5 kilometers away from the nesting beaches.

Copulation takes place in waters up to 28 meters deep. The female can mate with several males and has the ability to store sperm during the season. As for nesting, it occurs with a frequency of 1 to 3 years. However, more than 60% usually reproduce almost annually.

This species has three modes of reproduction: solitary, arribada, and mixed. Arribada is a synchronous behavior where females massively gather on a beach to nest.

However, one of the forms most used by the olive ridley turtle is solitary or scattered. In this, the laying of the eggs does not occur simultaneously, but individually. In some regions a mixture of both forms of nesting can occur, which is known as a mixed strategy.

Eder Omar Campos González

The researchers note that solitary nesting species use various beaches for oviposition, while arribada nesters show high fidelity to the nesting site.

Feeding

Lepidochelys olivacea is a generalist opportunistic predator. Their diet includes crustaceans, a great diversity of fish and their eggs, sea urchins, jellyfish, marine worms and algae, among others.

Also, they eat crustaceans, such as lobsters, crabs, shrimp, and mollusks. Within this last group are bivalves, squid and snails. Among the species that make up their diet, mollusks dominate 34.5%, while crustaceans account for around 27.6%.

In general, the groups of animals that it consumes are part of the zoobenthos of sandy areas. However, there are some exceptions. Such is the case of some species of the Scyphozoa class, especially Pelagia sp., And of the ketognaths, which make up the macroplankton.

Behavior

During the morning, the olive ridley turtle usually feeds and in the afternoon, it rises to the surface to sunbathe, trying to warm its body. In warmer regions, this reptile rarely goes out to receive the sun's rays.

To defend itself against a predator, it usually swims away from it or dives deeper. On land, the main predators of eggs are snakes, wild pigs, and possums. To counteract the attack of these animals, the female strongly flaps her forelimbs.

The main behavior that characterizes the Lepidochelys olivácea is synchronized massive nesting, known as arribadas. In these, a large group of females swim towards a beach, generally the same one where they were born, to lay their eggs.

Once there, they laboriously dig, with their hind limbs, conical nests approximately 4.5 meters deep. Then they deposit the eggs and cover them with sand.

References

1. Arteaga A, Guayasamin JM. (2019. Lepidochelys olivacea. Reptiles of Galapagos. Recovered from tropicalherping.com.
2. Satyaranjan Behera, Basudev Tripathy K. Sivakumar BC Choudhur (2015). Stomach Contents of Olive Ridley Turtles (Lepidochelys Olivacea) Occurring in Gahirmatha, Odisha Coast of India. Recovered from link.springer.com
3. ITIS (2019). Lepidochelys olivacea. Recovered from itis, gov.
4. T. Plotkin RA Byles DC Rosta lD. W. Owens (1995). Independent versus socially facilitated oceanic migrations of the olive ridley, Lepidochelys olivacea. Recovered from link.springer.com.
5. Abreu-Grobois, A, Plotkin, P. (2008). Lepidochelys olivacea. The IUCN Red List of Threatened Species 2008. Recovered from iucnredlist.org.
6. Herbst, P. (1999). Lepidochelys olivacea. Animal Diversity. Recovered from animaldiversity.org.
7. S. Fish and Wildlife Service (2018). Olive Ridley Sea Turtle (Lepidochelys olivacea). Recovered from fws.gov.
8. Wikipedia (2019). Olive ridley be turtle. Recovered from en.wikipedia.org.
9. The reptile database (2019). Lepidochelys olivacea (ESCHSCHOLTZ, 1829). Recovered from database.reptarium.cz.
10. MarineBio (2019). Olive Ridley Sea Turtles, Lepidochelys olivacea. Recovered from marinebio.org.