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The olive ridley sea turtle (''Lepidochelys olivacea''), also known commonly as the Pacific ridley sea turtle, is a
species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individu ...

species
of turtle in the
family In human society A society is a Social group, group of individuals involved in persistent Social relation, social interaction, or a large social group sharing the same spatial or social territory, typically subject to the same Politic ...
Cheloniidae Cheloniidae is a family of typically large marine turtles that are characterised by their common traits such as, having a flat streamlined wide and rounded shell and almost paddle-like flippers for their forelimbs. The six species that make up thi ...
. The species is the second-smallest and most abundant of all sea turtles found in the world. ''L. olivacea'' is found in warm and tropical waters, primarily in the Pacific and Indian Oceans, but also in the warm waters of the Atlantic Ocean. This turtle and the related Kemp's ridley turtle are best known for their unique mass nesting sites called ''arribadas'', where thousands of females come together on the same beach to lay eggs.


Taxonomy

The olive ridley sea turtle may have been first described as ''Testudo mydas minor'' by
Georg Adolf Suckow Georg Adolf Suckow sometimes Adolph (28 January 1751, Jena Jena (; ) is a German List of cities and towns in Germany, city and the second largest city in Thuringia. Together with the nearby cities of Erfurt and Weimar, it forms the central metrop ...
in 1798. It was later described and named ''Chelonia multiscutata'' by
Heinrich Kuhl Heinrich Kuhl (September 17, 1797 – September 14, 1821) was a German German(s) may refer to: Common uses * of or related to Germany * Germans, Germanic ethnic group, citizens of Germany or people of German ancestry * For citizens of Germany, ...
in 1820. Still later, it was described and named ''Chelonia olivacea'' by
Johann Friedrich von Eschscholtz Johann Friedrich Gustav von Eschscholtz (1 November 1793 – 7 May 1831)Sterling (1997) was a Baltic German physician, naturalist, and entomologist. He was one of the earliest scientific explorers of the Pacific region, making significant collect ...

Johann Friedrich von Eschscholtz
in 1829. The species was placed in the
subgenus In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a binomen, species name, in parentheses, placed ...
''Lepidochelys'' by
Leopold FitzingerImage:Fitzinger Leopold 1802-1884.png, 250px, Leopold Fitzinger. Leopold Joseph Franz Johann Fitzinger (13 April 1802 – 20 September 1884) was an Austrian zoologist. Fitzinger was born in Vienna and studied botany at the University of Vienna under ...
in 1843. After ''Lepidochelys'' was elevated to full
genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circumscribing) and classifying gr ...
status, the species was called ''Lepidochelys olivacea'' by
Charles Frédéric Girard Charles Frédéric Girard (8 March 1822 – 29 January 1895) was a French biologist specializing in ichthyology and herpetology. Born in Mulhouse, France, he studied at the College of Neuchâtel, Switzerland, as a student of Louis Agassiz. In 1847 ...
in 1858. Because Eschscholtz was the first to propose the
specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species In biology, a species is the basic unit of biological classi ...
''olivacea'', he is credited as the
binomial authority In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed ...
or
taxon In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechani ...
author in the valid name ''Lepidochelys olivacea'' (Eschscholtz, 1829). The parentheses indicate that the species was originally described in a different genus. The generic name, ''Lepidochelys'', is derived from the Greek words ''lepidos'', meaning scale, and ''chelys'', which translates to turtle. This could possibly be a reference to the supernumerary costal scutes characteristic of this genus. The
etymology Etymology ()The New Oxford Dictionary of English ''The'' () is a grammatical article Article often refers to: * Article (grammar) An article is any member of a class of dedicated words that are used with noun phrases to mark the identi ...
of the English vernacular name "olive" is somewhat easier to resolve, as its carapace is olive green in color. However, the origin of "ridley" is still somewhat unclear, perhaps derived from "riddle". ''Lepidochelys'' is the only genus of sea turtles containing more than one extant species: ''L. olivacea'' and the closely related '''' (Kemp's ridley).


Description

Growing to about 61 cm (2 ft) in
carapace A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...
length (measured along the curve), the olive ridley sea turtle gets its common name from its olive-colored carapace, which is heart-shaped and rounded. Males and females grow to the same size, but females have a slightly more rounded carapace as compared to males. The heart-shaped carapace is characterized by four pairs of pore-bearing inframarginal
scutes A scute or scutum (Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the ...
on the bridge, two pairs of prefrontals, and up to nine lateral scutes per side. ''L. olivacea'' is unique in that it can have variable and asymmetrical lateral scute counts, ranging from five to nine plates on each side, with six to eight being most commonly observed. Each side of the carapace has 12–14 marginal scutes. The carapace is flattened dorsally and highest anterior to the bridge. it has a medium-sized, broad head that appears triangular from above. The head's concave sides are most obvious on the upper part of the short snout. It has paddle-like fore limbs, each having two anterior claws. The upper parts are grayish-green to olive in color, but sometimes appear reddish due to
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic Photosynthesis is a process used by plants and other organisms to convert Conversion or convert may refer to: Arts, entertainment, and media * Co ...

algae
growing on the carapace. The bridge and hingeless
plastron The turtle shell is a shield for the ventral and dorsal parts of turtles (the Order (biology), order Testudines), completely enclosing all the vital organs of the turtle and in some cases even the head. It is constructed of modified bony elements ...

plastron
of an adult vary from greenish white in younger individuals to a creamy yellow in older specimens (maximum age is up to 50 years). Hatchlings are dark gray with a pale yolk scar, but appear all black when wet. Carapace length of hatchlings ranges from . A thin, white line borders the carapace, as well as the trailing edge of the fore and hind flippers. Both hatchlings and juveniles have serrated posterior marginal scutes, which become smooth with age. Juveniles also have three dorsal keels; the central longitudinal keel gives younger turtles a serrated profile, which remains until sexual maturity is reached. The olive ridley sea turtle rarely weighs over 50 kg (110 lb). Adults studied in
Oaxaca Oaxaca ( , also , , from nci, Huāxyacac ), officially the Free and Sovereign State of Oaxaca ( es, Estado Libre y Soberano de Oaxaca), is one of the 32 states that compose the political divisions of Mexico, Federative Entities of Mexico. It is ...
,
Mexico Mexico, officially the United Mexican States, is a country A country is a distinct territorial body or political entity A polity is an identifiable political entity—any group of people who have a collective identity, who are organi ...

Mexico
, ranged from ; adult females weighed an average of (n=58), while adult males weighed significantly less, averaging (n=17). Hatchlings usually weigh between . Adults are sexually dimorphic. The mature male has a longer and thicker tail, which is used for
copulation Sexual intercourse (or coitus or copulation) is a sexual activity typically involving the insertion and Pelvic thrust, thrusting of the penis into the vagina for Sexual stimulation, sexual pleasure, sexual reproduction, reproduction, or both.S ...
, and the presence of enlarged and hooked claws on the male's front flippers allows him to grasp the female's carapace during copulation. The male also has a longer, more tapered carapace than the female, which has a rounded, dome-like carapace. The male also has a more concave plastron, believed to be another adaptation for mating. The plastron of the male may also be softer than that of the female.


Distribution

The olive ridley turtle has a circumtropical distribution, living in tropical and warm waters of the Pacific and Indian Oceans from India, Arabia, Japan, and Micronesia south to southern Africa, Australia, and New Zealand. In the Atlantic Ocean, it has been observed off the western coast of Africa and the coasts of northern Brazil,
Suriname Suriname () or Surinam, officially known as the Republic of Suriname ( nl, Republiek Suriname ), is a country on the northeastern Atlantic coast of South America South America is a entirely in the and mostly in the , with a rela ...

Suriname
,
Guyana Guyana ( or ), officially the Cooperative Republic of Guyana, is a country on the northern mainland of South America and the capital city is Georgetown Guyana, Georgetown. Guyana is bordered by the Atlantic Ocean to the north, Brazil to the ...

Guyana
,
French Guiana French Guiana ( or ; french: link=no, Guyane ) is an overseas department/region and single territorial collectivity A single territorial collectivity (french: collectivité territoriale ''unique'') is a chartered subdivision of France ...

French Guiana
, and Venezuela. Additionally, the olive ridley has been recorded in the Caribbean Sea as far north as Puerto Rico. A female was found alive on an Irish Sea beach on the Isle of
Anglesey Anglesey (; cy, Ynys Môn ), an island off the north-west coast of Wales Wales ( cy, Cymru ) is a country A country is a distinct territory, territorial body or political entity. It is often referred to as the land of an individua ...
, Wales, in November 2016, giving this species its northernmost appearance. It was taken in by the nearby
Anglesey Sea Zoo The Anglesey Sea Zoo ( cy, Sw Môr Môn) is an aquarium and independent research and marine education centre on the south coast of Anglesey island in North Wales. Located just outside the village of Brynsiencyn, Anglesey Sea Zoo claims to be the l ...
, while its health was assessed. A juvenile female was found off the coast of
Sussex Sussex (), from the Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon England, e ...

Sussex
in 2020. The olive ridley is also found in the eastern Pacific Ocean from the
Galápagos Islands The Galápagos Islands (official name: , other Spanish language, Spanish name: , , ), part of the Republic of Ecuador, are an archipelago of High island, volcanic islands. They are distributed on either side of the equator in the Pacific Ocean ...
and Chile north to the
Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean The Pacific Ocea ...

Gulf of California
, and along the Pacific coast to at least Oregon. Migratory movements have been studied less intensely in olive ridleys than other species of marine turtles, but they are believed to use the coastal waters of over 80 countries. Historically, this species has been widely regarded as the most abundant sea turtle in the world. More than one million olive ridleys were commercially harvested off the coasts of Mexico in 1968 alone. The population of Pacific Mexico was estimated to be at least 10 million prior to the era of mass exploitation. More recently, the global population of annual nesting females has been reduced to about two million by 2004, and was further reduced to 852,550 by 2008. This indicated a dramatic decrease of 28 to 32% in the global population within only one generation (i.e., 20 years). Olive ridley sea turtles are considered the most abundant, yet globally they have declined by more than 30% from historic levels. These turtles are considered endangered because of their few remaining nesting sites in the world. The eastern Pacific turtles have been found to range from
Baja California Baja CaliforniaSometimes informally referred to as ('North Lower California') to distinguish it from both the Baja California Peninsula The Baja California Peninsula ( en, Lower California Peninsula, es, Península de Baja California) is ...
, Mexico, to Chile. Pacific olive ridleys nest around Costa Rica, Mexico, Nicaragua, and the northern Indian Ocean; the breeding colony in Mexico was listed as endangered in the US on July 28, 1978.


Nesting grounds

Olive ridley turtles are best known for their behavior of synchronized nesting in mass numbers, termed ''arribadas''. Females return to the same beach from where they hatched, to lay their eggs. They lay their eggs in conical nests about 1.5 ft deep, which they laboriously dig with their hind flippers."Olive ridley Turtle"
''wwfindia.org''.
In the Indian Ocean, the majority of olive ridleys nest in two or three large groups near Gahirmatha in
Odisha Odisha (English: , ), formerly Orissa (), is an States and union territories of India, Indian state located in East India, Eastern India. It is the List of states and union territories of India by area, 8th largest state by area, and the Li ...

Odisha
. The coast of Odisha in India is one of the largest mass nesting sites for the olive ridley, along with the coasts of Mexico and Costa Rica. In 1991, over 600,000 turtles nested along the coast of Odisha in one week. Nesting occurs elsewhere along the
Coromandel Coast The Coromandel Coast is the southeastern coastal region of the Indian subcontinent, bounded by the Utkal Plains to the north, the Bay of Bengal to the east, the Kaveri The Kaveri (also known as Cauvery, the name) is an Indian river ...
and
Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකාව, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon, and officially the Democratic Socialist Republic of Sri Lanka, is ...

Sri Lanka
, but in scattered locations. However, olive ridleys are considered a rarity in most areas of the Indian Ocean. They are also rare in the western and central Pacific, with known ''arribadas'' occurring only within the tropical eastern Pacific, in Central America and Mexico. In Costa Rica, they occur at Nancite and Ostional beaches. Two active ''arribadas'' are in Nicaragua, Chacocente and La Flor, with a small nesting ground in Pacific Panama. Historically, several ''arribadas'' were in Mexico, Playa Escobilla and Morro Ayuda in Oaxaca, and Ixtapilla in Michoacan are the three ''arribada'' beaches in the present . Although olive ridleys are famed for their ''arribadas'', many of the nesting grounds can only support relatively small to moderate-sized aggregations (about 1,000 nesting females). The overall contribution and importance of these nesting beaches to the population may be underestimated by the scientific community. Isolated nesting does also sporadically occur.


Foraging grounds

Some of the olive ridley's foraging grounds near Southern California are contaminated due to sewage, agricultural runoff, pesticides, solvents, and industrial discharges. These contaminants have been shown to decrease the productivity of the benthic community, which negatively affects these turtles, which feed from these communities. The increasing demand to build marinas and docks near Baja California and Southern California are also negatively affecting the olive ridleys in these areas, where more oil and gasoline will be released into these sensitive habitats. Another threat to these turtles is power plants, which have documented juvenile and subadult turtles becoming entrained and entrapped within the saltwater cooling intake systems.


Ecology and behavior


Reproduction

Mating is often assumed to occur in the vicinity of nesting beaches, but copulating pairs have been reported over 1,000 km from the nearest beach. Research from Costa Rica revealed the number of copulating pairs observed near the beach could not be responsible for the fertilization of the tens of thousands of
gravid In biology and medicine, human medicine, gravidity and parity are the number of times a woman is or has been pregnant (gravidity) and carried the pregnancies to a viable gestational age (parity). These terms are usually coupled, sometimes with addi ...
females, so a significant amount of mating is believed to have occurred elsewhere at other times of the year. The Gahirmatha Beach in Kendrapara district of Odisha (India), which is now a part of the Bhitarkanika Wildlife Sanctuary, is the largest breeding ground for these turtles. The Gahirmatha Marine Wildlife Sanctuary, which bounds the Bhitarkanika Wildlife Sanctuary to the east, was created in September 1997, and encompasses Gahirmatha Beach and an adjacent portion of the Bay of Bengal. Bhitarkanika mangroves were designated a Ramsar Wetland of International Importance in 2002. It is the world's largest known rookery of olive ridley sea turtles. Apart from Gahirmatha rookery, two other mass nesting beaches have been located, which are on the mouth of rivers Rushikulya and Devi. The spectacular site of mass congregation of olive ridley sea turtles for mating and nesting enthralls both the scientists and the nature lovers throughout the world. Olive ridley sea turtles migrate in huge numbers from the beginning of November, every year, for mating and nesting along the coast of Orissa. Gahirmatha coast has the annual nesting figure between 100,000 and 500,000 each year. A decline in the population of these turtles has occurred in the recent past due to mass mortality. The olive ridley sea turtle has been listed on Schedule – I of the Indian Wildlife (Protection) Act, 1972 (amended 1991). The species is listed as vulnerable under IUCN. The sea turtles are protected under the 'Migratory Species Convention' and Convention of International Trade on Wildlife Flora and Fauna (CITES). India is a signatory nation to all these conventions. The homing characteristics of the ridley sea turtles make them more prone to mass casualty. The voyage to the natal nesting beaches is the dooming factor for them. Since Gahirmatha coast serves as the natal nesting beach for millions of turtles, it has immense importance on turtle conservation. Olive ridleys generally begin to aggregate near nesting beaches about two months before nesting season, although this may vary throughout their range. In the eastern Pacific, nesting occurs throughout the year, with peak nesting events (''arribadas'') occurring between September and December. Nesting beaches can be characterized as relatively flat, midbeach zone, and free of debris.. Retrieved 16 April 2013. Beach
fidelity Fidelity is the quality of faithfulness Eugene Santos or Faithfulness is the concept of unfailingly remaining loyal to someone or something, and putting that loyalty into consistent practice regardless of extenuating circumstances. It may be ex ...

fidelity
is common, but not absolute. Nesting events are usually nocturnal, but diurnal nesting has been reported, especially during large ''arribadas''. Exact age of sexual maturity is unknown, but this can be somewhat inferred from data on minimum breeding size. For example, the average carapace length of nesting females (n = 251) at Playa Nancite, Costa Rica, was determined to be 63.3 cm, with the smallest recorded at 54.0 cm. Females can lay up to three
clutch A clutch is a mechanical device that engages and disengages power transmission Transmission may refer to: Science and technology * Power transmissionPower transmission is the movement of energy from its place of generation to a location wh ...
es per season, but most only lay one or two clutches. The female remains near shore for the internesting period, which is about one month. Mean clutch size varies throughout its range and decreases with each nesting attempt. A mean clutch size of 116 (30–168 eggs) was observed in
Suriname Suriname () or Surinam, officially known as the Republic of Suriname ( nl, Republiek Suriname ), is a country on the northeastern Atlantic coast of South America South America is a entirely in the and mostly in the , with a rela ...

Suriname
, while nesting females from the eastern Pacific were found to have an average of 105 (74–126 eggs). The incubation period is usually between 45 and 51 days under natural conditions, but may extend to 70 days in poor weather conditions. Eggs incubated at temperatures of 31 to 32 °C produce only females; eggs incubated at 28 °C or less produce solely males; and incubation temperatures of 29 to 30 °C produce a mixed-sex clutch. Hatching success can vary by beach and year, due to changing environmental conditions and rates of nest predation.


Habitat

Most observations are typically within 15 km of mainland shores in protected, relatively shallow marine waters (22–55 m deep). Olive ridleys are occasionally found in open waters. The multiple habitats and geographical localities used by this species vary throughout its lifecycle.


Feeding

The olive ridley is predominantly
carnivorous A carnivore , meaning "meat eater" (Latin, ''caro'', genitive ''carnis'', meaning "meat" or "flesh" and ''vorare'' meaning "to devour"), is an organism, animal whose food and energy requirements derive solely from animal Tissue (biology), tissu ...
, especially in immature stages of its lifecycle. Animal prey consists of protochordates or invertebrates, which can be caught in shallow marine waters or
estuarine An estuary is a partially enclosed coastal body of brackish water Brackish water, also sometimes termed brack water, is water occurring in a natural environment having more salinity File:IAPSO Standard Seawater.jpg, upInternational Associatio ...
habitats. Common prey items include
jellyfish Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum In zoological nomenclature The International Code of Zoological Nomenclature (ICZN) is a widely accepted Con ...

jellyfish
,
tunicates A tunicate is a marine invertebrate Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This includes all animals apart from the subphylum ...
,
sea urchins ''Sea Urchins'' was a kidult television series (in three series) produced by Television New Zealand from 1980 to 1984. It starred Rebecca Gibney in her first television role, Bruce Allpress, John Bach, Roy Billing and Robert Rakete. Described ...

sea urchins
,
bryozoans Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of aquatic invertebrate Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), ...
,
bivalves Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of marine and freshwater Mollusca, molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged p ...
, snails, shrimp, crabs, rock lobsters, and
sipunculid The Sipuncula or Sipunculida (common names sipunculid worms or peanut worms) is a group containing about 162 species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, ...
worms. Additionally, consumption of jellyfish and both adult fish (e.g. ''Sphoeroides'') and fish eggs may be indicative of pelagic (open ocean) feeding. The olive ridley is also known to feed on filamentous algae in areas devoid of other food sources. Captive studies have indicated some level of
cannibalistic Cannibalism is the act of consuming another individual of the same species as food Food is any substance consumed to provide nutritional support for an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμ ...
behavior in this species.


Threats

Known predators of olive ridley eggs include raccoons, coyotes, feral dogs and pigs,
opossums The opossum ( or ) is a marsupial Marsupials are any members of the mammal Mammals (from Latin language, Latin , 'breast') are a group of vertebrate animals constituting the class (biology), class Mammalia (), and characterized by the ...
, coatimundi, caimans,
ghost crabs Ghost crabs are semiterrestrial crabs of the subfamily (biology), subfamily Ocypodinae. They are common shore crabs in tropical and subtropical regions throughout the world, inhabiting deep burrows in the intertidal zone. They are generalist speci ...
, and the sunbeam snake. Hatchlings are preyed upon as they travel across the beach to the water by vultures,
frigate bird Frigatebirds (also listed as "frigate bird", "frigate-bird", "frigate", "frigate-petrel") are a Family (biology), family of seabirds called Fregatidae which are found across all tropical and subtropical oceans. The five extant species are classif ...
s, crabs,
raccoon The raccoon ( or , ''Procyon lotor''), sometimes called the common raccoon to distinguish it from other species, is a medium-sized mammal Mammals (from Latin Latin (, or , ) is a classical language belonging to the Italic bra ...

raccoon
s,
coyote The coyote (''Canis latrans'') is a species of canis, canine native to North America. It is smaller than its close relative, the wolf, and slightly smaller than the closely related eastern wolf and red wolf. It fills much of the same ecologica ...

coyote
s,
iguana ''Iguana'' (, ) is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), c ...

iguana
s, and snakes. In the water, hatchling
predator Predation is a biological interaction In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical en ...

predator
s most likely include oceanic fishes,
shark Sharks are a group of elasmobranch fish characterized by a Chondrichthyes#Skeleton, cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified withi ...

shark
s, and crocodiles. Adults have relatively few known predators, other than sharks, and
killer whale The killer whale or orca (''Orcinus orca'') is a toothed whale The toothed whales (also called odontocetes, systematic name Odontoceti) are a parvorder of cetacea Cetaceans (from la, Cetus (mythology), cetus, lit=whale, from grc, κ ...

killer whale
s are responsible for occasional attacks. On land, nesting females may be attacked by
jaguar The jaguar (''Panthera onca'') is a large felidae, cat species and the only extant taxon, living member of the genus ''Panthera'' native to the Americas. With a body length of up to and a weight of up to , it is the largest cat species in t ...

jaguar
s. Notably, the jaguar is the only cat with a strong enough bite to penetrate a sea turtle's shell, thought to be an evolutionary adaption from the
Holocene extinction The Holocene extinction, otherwise referred to as the sixth mass extinction or Anthropocene extinction, is an ongoing extinction event of species during the present Holocene epoch (geology), epoch (with the more recent time sometimes called Anthr ...
event. In observations of jaguar attacks, the cats consumed the neck muscles of the turtle and occasionally the flippers, but left the remainder of the turtle carcass for scavengers as most likely, despite the strength of its jaws, a jaguar still cannot easily penetrate an adult turtle's shell to reach the internal organs or other muscles. In recent years, increased predation on turtles by jaguars has been noted, perhaps due to habitat loss and fewer alternative food sources. Sea turtles are comparatively defenseless in this situation, as they cannot pull their heads into their shells like freshwater and terrestrial turtles. Females are often plagued by
mosquito Mosquitoes are members of a group of almost 3,600 species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defin ...

mosquito
s during nesting. Humans are still listed as the leading threat to ''L. olivacea'', responsible for unsustainable egg collection, slaughtering nesting females on the beach, and direct harvesting adults at sea for commercial sale of both the meat and hides. Other major threats include mortality associated with boat collisions, and incidental takes in fisheries.
Trawling Trawling is a method of fishing Fishing is the activity of trying to catch fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition a ...
,
gill net Gillnetting is a fishing method that uses gillnets: vertical panels of netting that hang from a line with regularly spaced floaters that hold the line on the surface of the water. The floats are sometimes called "corks" and the line with corks is g ...
s, ghost nests,
longline fishingLong line or longline may refer to: *''Long Line ''Long Line'' is the fourth solo album by Peter Wolf, released in 1996 in music, 1996. The album marked a shift in Wolf's music from pop rock to a bluesier rock with more personal, introspective lyr ...
, and pot fishing have significantly affected olive ridley populations, as well as other species of marine turtles. Between 1993 and 2003, more than 100,000 olive ridley turtles were reported dead in Odisha, India from fishery-related practices. In addition, entanglement and ingestion of
marine debris Marine debris, also known as marine litter, is human-created waste Waste (or wastes) are unwanted or unusable materials. Waste is any substance which is discarded after primary use, or is worthless, defective and of no use. A by-produ ...

marine debris
is listed as a major threat for this species. Coastal development, natural disasters,
climate change Contemporary climate change includes both the global warming caused by humans, and its impacts on Earth's weather patterns. There have been previous periods of climate change, but the current changes are more rapid than any known even ...
, and other sources of
beach erosion Coastal erosion is the loss or displacement of land, or the long-term removal of sediment and rocks along the coastline due to the action of Wind wave, waves, Ocean current, currents, tides, wind-driven water, waterborne ice, or other impacts ...
have also been cited as potential threats to nesting grounds. Additionally, coastal development also threatens newly hatched turtles through the effects of light pollution. Hatchlings which use light cues to orient themselves to the sea are now misled into moving towards land, and die from dehydration or exhaustion, or are killed on roads. The greatest single cause of olive ridley egg loss, though, results from ''arribadas'', in which the density of nesting females is so high, previously laid nests are inadvertently dug up and destroyed by other nesting females. In some cases, nests become cross-contaminated by
bacteria Bacteria (; common noun bacteria, singular bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typ ...

bacteria
or pathogens of rotting nests. For example, in Playa Nancite, Costa Rica, only 0.2% of the 11.5 million eggs produced in a single ''arribada'' successfully hatched. Although some of this loss resulted from
predation Predation is a biological interaction In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical en ...

predation
and high tides, the majority was attributed to
conspecifics Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organis ...
unintentionally destroying existing nests. The extent to which ''arribadas'' contribute to the population status of olive ridleys has created debate among scientists. Many believe the massive reproductive output of these nesting events is critical to maintaining populations, while others maintain the traditional ''arribada'' beaches fall far short of their reproductive potential and are most likely not sustaining population levels. In some areas, this debate eventually led to legalizing egg collection.


Economic importance

Historically, the olive ridley has been exploited for food, bait, oil, leather, and
fertilizer A fertilizer (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American E ...

fertilizer
. The meat is not considered a delicacy; the egg, however, is esteemed everywhere. Egg collection is illegal in most of the countries where olive ridleys nest, but these laws are rarely enforced. Harvesting eggs has the potential to contribute to local economies, so the unique practice of allowing a sustainable (legal) egg harvest has been attempted in several localities. Numerous case studies have been conducted in regions of ''arribadas''
beach A beach is a landform alongside a body of water which consists of loose particles. The particles composing a beach are typically made from Rock (geology), rock, such as sand, gravel, shingle beach, shingle, pebbles, etc., or biological so ...

beach
es to investigate and understand the socioeconomic, cultural, and political issues of egg collection. Of these, the legal egg harvest at Ostional, Costa Rica, has been viewed by many as both biologically sustainable and economically viable. Since egg collection became legal in 1987, local villagers have been able to harvest and sell around three million eggs annually. They are permitted to collect eggs during the first 36 hours of the nesting period, as many of these eggs would be destroyed by later nesting females. Over 27 million eggs are left unharvested, and villagers have played a large role in protecting these nests from predators, thereby increasing hatching success. Most participating households reported egg harvesting as their most important activity, and profits earned were superior to other forms of available employment, other than tourism. The price of Ostional eggs was intentionally kept low to discourage illegal collection of eggs from other beaches. The Ostional project retained more local profits than similar egg-collection projects in Nicaragua, but evaluating egg-harvesting projects such as this suffers from the short timeline and site specificity of findings. In most regions, illegal poaching of eggs is considered a major threat to olive ridley populations, thus the practice of allowing legal egg harvests continues to attract criticism from conservationists and sea turtle biologists. Plotkin's ''Biology and Conservation of Ridley Sea Turtles'', particularly the chapter by Lisa Campbell titled "Understanding Human Use of Olive Ridleys", provides further research on the Ostional harvest (as well as other harvesting projects). Scott Drucker's documentary, ''Between the Harvest'', offers a glimpse into this world and the debate surrounding it.


Conservation status

The olive ridley is classified as vulnerable according to the
International Union for Conservation of Nature and Natural Resources The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization An international organization (also known as an international institu ...
, and is listed in Appendix I of
CITES CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty A multilateral treaty is a treaty A treaty is a formal, leg ...

CITES
. These listings were largely responsible for halting the large-scale commercial exploitation and trade of olive ridley skins. The
Convention on Migratory Species The Convention on the Conservation of Migratory Species of Wild Animals, also known as the Convention on Migratory Species (CMS) or the Bonn Convention, is an international agreement that aims to conserve migratory species throughout their ran ...
and the Inter-American Convention for the Protection and Conservation of Sea Turtles have also provided olive ridleys with protection, leading to increased conservation and management for this marine turtle. National listings for this species range from
endangered An endangered species is a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group ...

endangered
to
threatened Threatened Species are any species (including animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume org ...
, yet enforcing these sanctions on a global scale has been unsuccessful for the most part. Conservation successes for the olive ridley have relied on well-coordinated national programs in combination with local communities and nongovernment organizations, which focused primarily on public outreach and education. ''Arribada'' management has also played a critical role in conserving olive ridleys. Lastly, enforcing the use of turtle excluder devices in the shrimp-trawling industry has also proved effective in some areas. Globally, the olive ridley continues to receive less conservation attention than its close relative, Kemp's ridley (''L. kempii''). Also, many schools arrange trips for students to carry out the conservation project, especially in India. Several projects worldwide seek to preserve the olive ridley sea turtle population. For example, in Nuevo Vallarta, Mexico, when the turtles come to the beach to lay their eggs, some of them are relocated to a hatchery, where they have a much better chance to survive. If the eggs were left on the beach, they would face many threats such as getting washed away with the tide or being poached. Once the eggs hatch, the baby turtles are carried to the beach and released. Another major project in India involved in preserving the olive ridley sea turtle population was carried out in Chennai, where the Chennai wildlife team collected close to 10,000 eggs along the Marina coast, of which 8,834 hatchlings were successfully released into the sea in a phased manner."Over 8000 turtle hatchlings released"
''
Deccan Chronicle ''Deccan Chronicle'' is an Indian English-language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon England, early medieval England, which has eventually become the World language, leadi ...
'', Chennai, 23 May 2014. Retrieved on 23 May 2014.


References


Further reading

* (1829). ''Zoologischer Atlas, enthaltend Abbildungen und Beschreibungen neuer Thierarten, während des Flottcapitains von Kotzbue zweiter Reise um die Welt, auf der Russisch-Kaiserlichen Kriegsschlupp Predpriaetië in den Jahren 1823 — 1826. Erstes Heft''. Berlin: G. Reimer. iv + 17 pp. + Plates I-V. (''Chelonia olivacea'', new species, pp. 3–4 + Plate III). (in German and Latin). * Smith HM, Brodie ED Jr (1982). ''Reptiles of North America: A Guide to Field Identification''. New York: Golden Press. 240 pp. (paperback), (hardcover). (''Lepidochelys olivacea'', pp. 36–37). * Stebbins RC (2003). ''A Field Guide to Western Reptiles and Amphibians, Third Edition''. The Peterson Field Guide Series. Boston and New York: Houghton Mifflin Company. xiii + 533 pp., 56 plates. . (''Lepidochelys olivacea'', p. 259 + Plate 23). * *


External links


NOAA Fisheries: Olive ridley sea turtle (''Lepidochelys olivacea'') webpage

"Olive Ridley Project" webpage
* {{DEFAULTSORT:turtle, sea, ridley, olive
olive ridley sea turtle The olive ridley sea turtle (''Lepidochelys olivacea''), also known commonly as the Pacific ridley sea turtle, is a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an or ...
Pantropical fauna Reptiles of Mexico Fauna of Western Mexico Natural history of Balochistan, Pakistan
olive ridley sea turtle The olive ridley sea turtle (''Lepidochelys olivacea''), also known commonly as the Pacific ridley sea turtle, is a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an or ...
Taxa named by Johann Friedrich von Eschscholtz Endangered animals ESA threatened species