Unlike other sea turtles, female Kemp's ridley turtles come ashore to lay their eggs in the daylight hours.
Photograph by Bill Curtsinger.
The Kemp’s ridley turtle is the world’s most endangered sea turtle, and with a worldwide female nesting population roughly estimated at just 1,000 individuals, its survival truly hangs in the balance. Their perilous situation is attributed primarily to the over-harvesting of their eggs during the last century. And though their nesting grounds are protected and many commercial fishing fleets now use turtle excluder devices in their nets, these turtles have not been able to rebound.
For this reason, their nesting processions, called arribadas, make for especially high drama. During an arribada, females take over entire portions of beaches, lugging their big bodies through the sand with their flippers until they find a satisfying spot to lay their eggs. Even more riveting is the later struggle to the ocean of each tiny, vulnerable hatchling. Beset by predators, hatchlings make this journey at night, breaking out of their shells using their caruncle, a single temporary tooth grown just for this purpose.
Found primarily in the Gulf of Mexico, but also as far north as Nova Scotia, Kemp’s ridleys are among the smallest sea turtles, reaching only about 2 feet (65 centimeters) in shell length and weighing up to 100 pounds (45 kilograms). Their upper shell, or carapace, is a greenish-grey color, and their bellies are off-white to yellowish.
They prefer shallow waters, where they dive to the bottom to feed on crabs, which are their favorite food, and other shellfish. They also eat jellyfish, and occasionally munch on seaweed and sargassum. They may live to be 50 years old.
Females aren’t sexually mature until about ten to twelve years of age. They nest every one to three years and may lay several clutches of eggs each season. Highly migratory animals, they often travel hundreds of miles (kilometers) to reach their nesting beach, usually the same beach they hatched from.
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Type: Reptile
Diet: Omnivore
Average lifespan in the wild: About 50 years
Size: 2 ft (65 cm)
Weight: 100 lbs (45 kg)
Did you know? A 1947 amateur film showed some 40,000 female Kemp's ridley turtles nesting in Mexico in a single day. Today, it is estimated that only about 1,000 breeding females exist worldwide.
Size relative to a 6-ft (2-m) man:
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The top of the turtle is called the carapace and the bottum is called the plastron.
Sea Turtles
Sea Turtles
Sea Turtles are ancient creatures. Some scientists say they are over 110 million years old, while others claim their lineage goes back 140 million years. They were here before the dinosaurs roamed the planet; and yet today, all species are on the IUCN (World Conservation Union) Red List meaning they are facing a high risk of global extinction. The United States Endangered Species Act (ESA) also places sea turtles species as endangered. In addition and unfortunately, scientists believe that leatherback sea turtles could be facing extinction in as little as ten years. Save the Turtles, Inc, stands humbled by these gentle creatures and works towards their survival.
About Sea Turtles
- Air breathing reptiles, but can spend hours submerged in the ocean.
- Adult females must return to land in order to lay their eggs. Many species return to the same beach where they were born to lay their eggs.
- Are found in oceans all over the world, except the Arctic Ocean
- May migrate hundreds or thousands of miles. It is believed that they use the earth’s magnetic forces to navigate throughout the oceans.
- Most prefer open water, but they are also encountered in coastal waters near reefs and estuaries.
- Are sensitive to smells and sound. They hear through eardrums below their skin.
- The adult green turtles are unique among sea turtles in that they are herbivorous, feeding primarily on seagrasses and algae. Most sea turtles are mainly carnivores and feed on jellyfish, tunicates (ascidians, sea squirts), sponges (one of a few animals that eat them), soft corals, crabs, squids and fishes.
- All 7 species of marine turtles are listed under the Endangered Species Act (ESA).
Sea Turtles & Taxonomy: the scientific classification system
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia (includes turtles, snakes, lizards, and crocodiles)
Order: Testudines (includes turtles, tortoises and terrapins). See additional notes below that explain the difference between these categories.
Family: Dermochelyidae: The Leatherback is the only non-extinct species remaining in this family and is distinguished from all other turtles by the semi-flexible “leathery” skin on its outer shell
Cheloniidae: Most scientists group remaining sea turtle species under the family Cheloniidae. These species have shells covered with hard bony plates or scutes
How to Distinguish the Seven Different Species
The outer shell or carapace is the primary feature used in the identification of sea turtle species. The number of scutes on the carapace, their shape, coloring and patterning is specific to each species. Another anatomical feature utilized to distinguish between sea turtles are the prefrontal scales located on the turtle’s head.
There are seven living species of sea turtles (the first name listed is based on their physical characteristics and this common name varies in different counties). The name in parenthesis refers to their scientific taxonomy of species and genus:
Sea Turtles are Global:
Although each species has their own preference for nesting grounds, migration patterns and diet, they also have similar characteristics and unfortunately share the same threats.
Migration & Navigation
There has been extensive research conducted regarding the sea turtles’ abilities to return to their nesting regions. They may migrate hundreds or even thousands of miles. In the water, their path is greatly affected by powerful currents. Despite their limited vision, and lack of landmarks in the open water, turtles are able to retrace their migratory paths. One explanation of this phenomenon is that sea turtles use the earth’s magnetic fields to navigate.
General Behavior
Sea turtles are generally solitary and usually interact with one another only for courting and mating. Sexual maturity varies with species, ranging early with the hawksbill at three years and age twenty to fifty for the leatherback. During mating season, two or more males may court a female and the male attaches himself to the back of the female's shell and then folds his long tail under her shell to copulate. Fertilization is internal and copulation takes place on the surface or underwater, often close to shore. Females may mate with several males just prior to nesting season and store the sperm for several months. When she finally lays her eggs, they will have been fertilized by a variety of males. This behavior may help keep genetic diversity high in the population.
Nesting & Reproduction
Sea turtles usually nest in intervals of two to three years although some nest yearly. Depending on the species, females may nest from one to ten times during a nesting season. Only the females come ashore to the beach to lay their eggs a few weeks after mating.
When the female Leatherback is ready to nest, she will choose a beach without a coral reef, one close to the deep water, such as ’s Beach. Crawling up from the ocean, she will locate a dry area and begin the arduous task of nest excavation. Using her flippers and the rotation of her body, she will dig an egg cavity that is approximately 70 centimeters deep. She will then lay 80 to 100 eggs, a process that can take over two hours. Eggs are often referred to as the size of billiard balls: she lays an average of 80 fertilized eggs and 30 smaller, unfertilized eggs in each nest. After she is finished, she will carefully cover and camouflage the clutch, and may even construct false nests to fool predators. Her role now complete, she will depart to the ocean, leaving her eggs to their fate.
Remarkably, most female turtles share a nesting instinct that drives them to return to the beach of their birth, or natal beach, in order to lay eggs. In fact, her ability to successfully reproduce depends on the ecological health of this original habitat. However, recent satellite tracking data indicates that the Leatherback, unique among turtles in many ways, may return to a range area or region, rather than a natal beach. The Caribbean coastline of Costa Rica is an example of one of the most important Leatherback nesting regions in the world.
When the female turtle comes ashore at night to lay her eggs, she will first dig a body cavity with her front flippers, and then use her back flippers to dig out the nest. Depending upon the species, 80-120 eggs will be deposited in the cavity. Afterwards the female will laboriously cover the nest with sand and often even create another false nest to confuse predators, before she finally crawls back to the sea. Incubation varies with species, clutch size (number of eggs) and temperature, but averages from 45-70 days.
Hatchlings
Hatchlings use a caruncle, a temporary egg tooth to break open their shells. It may take several days for a group of hatchlings to dig their way up out of the nest cavity. Although they usually emerge at night, coolness of sand temperature and other factors influence their emergence. The hatchlings crawl towards the ocean in small groups. They must make it to the ocean quickly so they don’t die from dehydration or predators. When a hatchling reaches the surf, it swims continuously for 24-48 hours to get to deeper water away from predators. The turtles must survive several years in a relatively protected area away from predators and one with ample food supply. Juveniles will spend time eating and growing in habitats near the shore. Once they reach adulthood, they migrate to find a primary feeding ground. During mating season, the sea turtles will migrate closer to their nesting beach.
Why Sea Turtles Are Endangered
Unfortunately, there are many reasons why sea turtles are now at risk
- Human harvesting of turtles and their eggs.
- Destruction of nesting habitats.
- Commercial fisheries who use longline fishing practices or gill nets and do not use Turtle Excluder Devices (TEDS),
- Pollution affecting nesting habitats and/or species: such as entanglement in marine debris; plastic debris, and commercial and industrial ocean water pollution from oil spills and chemical waste.
- Global Warming.
Vital to the Eco-system
Sea turtles contribute to the delicate balance of ecosystems in our oceans and on the beaches where they nest. Their presence helps replenish both sea and beach nutrients and helps maintain the equilibrium of marine vegetation. For example, without Green turtles to feed on sea grass, the grasses would become overgrown and diseased which would have a negative impact on the many species that rely on this vegetation for sustenance. Sea turtles also play a significant role in balancing the oceans’ food chain. Leatherbacks for instance, consume large quantities of jellyfish, which feed on fish larvae. Some scientists are now looking at the possibility that the severe decline of Leatherback turtles over recent decades may have allowed for a proliferation of jellyfish, thus contributing to the drop in fish populations in the world’s oceans.
Sea turtles also support the health of our terrestrial ecosystem. The nutrients from their eggs bring food energy to species on beaches and sand dunes, which has an out-rippling effect to species in surrounding areas. The truth is that our planetary ecosystems are so intricately intertwined that it is difficult to predict just how far ranging the implications are when a global species such as the sea turtle, declines or is lost forever.
Scott Eckert’s (PhD) testimony to the Ocean Commission provides many examples of the interconnectedness of sea turtles and the eco-system:
Eckert also quotes another scientist, Dr. Nat Frazer, who eloquently describes their importance:
"Envision this with me . . . millions of sea turtles pulsing ashore onto the beaches . . . fertilizing the rims of thousands of islands and two continents. And after this wave of nutrients enters the rims, it is pulsed on up and into the interior lands in successive waves of biological transport. Year after year – tons of nutrients and billions of kilojoules of energy in a predictable, regular cycle – for tens of millions of years.
Envision this with me . . . millions of turtles grazing on seagrass beds, stimulating primary productivity at the base of the ocean’s food chain. And this surge of increased productivity works its way up the food chain, nourishing shrimp, mollusks, lobsters, and fish – as well as eventually pulsing onto the shore in the annual ballet of nesting activity.
Envision this with me . . . millions of sea turtles nibbling on sponges – trimming back the invading poriferans that otherwise would overgrow and shut down the coral reef machine. A constant system of checks and balances that also contributes to the gift of energy that sea turtles offer to the land each year in the form of nests and eggs. Year after year, for tens of million of years, the ecosystem engineers, these hawksbill and green and loggerhead and ridley and leatherback turtles, shape and improve and fine-tune the complex and mysterious and marvelous cybernetic machines of the oceans."
We are a non-profit organization dedicated to sea turtle conservation, and we are proud to be a vital link to the international efforts of protecting marine life.
We appreciate gathering some of our data from the resources below. Many of these websites have additional pages with links that will provide more detailed information about sea turtles. In addition, we gratefully acknowledge the photographers who have given us permission to use their turtle photos. Many of our photographs were found on the sea turtle image library at http://www.seaturtle.,org
Sea Turtle Resources
IUCN - The World Conservation Union: For information on Taxonomy and endangered species
Article by P.Tyson, Impact on Animals involving the Magnetic Field on animals
Amazing turtle information including satellite tracking
Also, see drawings of turtles and taxonomy
Taxonomy of the leatherback sea turtle
Endangered Species Act home page
Great page to see photos of all species
Important Political Action and other valuable information: Sea Turtle Restoration Project
Information on the difference between turtles, tortoises and terrapins
Scott A. Eckert, PhD: Testimony before the U.S. Commission on Ocean Policy (PDF file, requires Adobe Acrobat Reader) with quote from Frazer, Nat B. 2001. Management and Conservation Goals for Marine Turtles.
Sea Turtles & Eco-system (PDF file, requires Adobe Acrobat Reader)
Kemp's Ridley (Lepidochelys kempi)
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In 1995, this Kemp's ridley was one of several kept in a small tank at the Cayman island Turtle Farm. At the time, it was possible that these Kemp's ridleys might soon have been the only ones surviving on the planet. In recent years, the population of Kemp's has slowly started to recover.
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The big threat to the kempi today is no longer the coyotes or egg hunters that brought about the original decline. The factor to reckon with now is incidental catch by shrimp trawlers. With the breeding population down to no more than twelve hundred mature females, each turtle caught by a net dragged for other species represents a significant loss. So despite the most powerful rescue effort that any sea turtle has ever received, Kemp's ridley is by all odds the most precariously ensconced marine turtle in the world.
Archie Carr
The Sea Turtle - So Excellent A Fishe
p. 241
1986, University of Texas Press
Some of the following is based on information from the Recovery Plan for U.S. Population of Kemp's Ridley Sea Turtle, U.S Fish and Wildlife Service and National Marine Fisheries Service, 1992. Obtained from the U.S. National Marine Fisheries Service, and used with their kind permission.
Current Status
Kemp's Ridley (Lepiochelys kempii) has received protection in Mexico since the 1960s and was listed as endangered throughout its range in 1970 under United States law.
In 1963, using a film made in 1947 by the amateur cameraman Ing. Herrerra, Archie Carr and Henry Hildebrand estimated that on the day the film was made, 40,000 Kemp's ridley females nested on a single beach in northeastern Mexico. This arribada indicates that a much larger adult population existed.
The April 2001 Marine Turtle Newsletter carried a report that in 2000, slightly over 6,000 nests were counted. This is excellent news, since the estimated number of nests in 1985 was fewer than 200. The Kemp's is a long way from full recovery, however.
The Recovery Plan has this to say:
"The population crash that occurred between 1947 and the early 1970s may have been the result of both intensive annual harvest of the eggs and the mortality of juveniles and adults in trawl fisheries (Magnuson et al. 1990). The recovery of the species has been forestalled primarily by incidental mortality in commercial shrimping, preventing adequate recruitment into the breeding population."
Goal
Because the Kemp's ridley turtle at the time had only a single known nesting site (Rancho Nuevo, Mexico), inhabits a much restricted breeding range, and faces increasing threats from the human species, the Recovery Plan admits that a recovery might not be possible. The immediate goal of the Plan was to move the Kemp's ridley from the Endangered list to the Threatened list.
Today, there is better protection for the nesting beaches and Turtle Excluder Devices (TEDs) are mandatory on shrimp boats. The Kemp's population has responded favourably, with a slow but steady increase in annual nests counts. The recovery is by no means certain, but signs are encouraging.
Description
Kemp's ridley and its cousin, the olive ridley, are the smallest known sea turtles. Adults generally weigh less than 45 kg. The straight carapace measures around 65 cm, and is nearly as wide.
The colour changes significantly as they mature. Hatchlings are grey-black top and bottom, while adults have a lighter grey-olive carapace and cream-white or yellowish plastron.
Threats
It is not clear that Kemp's ridleys have ever been hunted for their meat, although heavy exploitation of marine turtles around the turn of the century might well have included the Kemp's. Today, the Kemp's ridley faces two grim threats: loss of their nesting beaches, and death by drowning in shrimp trawls.
Nesting Environment
A major threat to the Kemp's ridley nesting beach is human encroachment. Parts of the nesting area are officially protected. In the past, enforcement was sometimes a problem, but protection has improved in recent years. The nesting sites are also vulnerable to the threats described in Threats To Marine Turtles. The Kemp's is particularly vulnerable to the loss of nesting habitat, since nearly all known nests of the Kemp's are concentrated on a single beach in Mexico.
Commercial Fisheries
The largest threat to the Kemp's ridley continues to be death by drowning in shrimp nets. Between 500 to 5,000 are killed in this way each year.
In 1987, the shrimping fleet around the Gulf of Mexico and south Atlantic caught an estimated 45,000 or more turtles, killing approximately 11,000. Some estimates run the numbers 3 to 4 times higher. Sea turtles wash up with alarming regularity on beaches where the trawling and gill netting activity is high.
A simple device called a TED has existed for many years and has been proven effective in reducing the number of drownings. TEDs are designed to keep objects larger than a shrimp out of the net. Debris, turtles, and other bycatch escape from the net without adversely affecting the shrimp catch.
In the U.S., both federal and state governments have spent considerable time and money to promote the use of TEDs, hoping that shrimpers would use the devices voluntarily. Unfortunately, there was strong opposition from the shrimping industry. In 1989, U.S. federal regulations required the use of TED's by shrimp trawlers operating in U.S. waters. Compliance remains a problem, but since the TED regulations were implemented, the Kemp's has begun a slow recovery.
The Sea Turtle Restoration Project has been organizing support for a marine preserve along the Texas coast to protect the Kemp's ridley. You can learn more about this campaign by visiting their website at www.seaturtles.org.
Marine Pollution and Debris
The two primary feeding grounds for adult Kemp's are both near major areas of oil exploration and production. The nesting beach at Rancho Nuevo was the victim of an oil spill in 1979 and continues to be vulnerable.
Kemp's ridley are also vulnerable to the pollution threats common to all marine turtles, as described in Threats to Marine Turtles.
Kemp's Ridley Quick Facts
The Kemp's Ridley is the most endangered of all marine turtles. Only 580 females nested in 1994, compared to 40,000 on a single day in 1947.
- Named for Richard M. Kemp, a fisherman interested in natural history who submitted the type specimen from Florida
- Feeds mainly on crabs
- Nesting information: 40,000 females nesting in 1947, estimated 5,000 in 1968, and in years 1978-1991, nesting rarely reached 200 females
- The smallest of all living sea turtles, weight of an adult averages less than 45 kg
- Adult Kemp shells are as round as they are wide
- Hatchlings: 4-5 cm in length
- Nesting season from April through July, at Rancho Nuevo, Mexico; almost no nesting takes place at any other beach
- The largest single source of Kemp mortalities is drowning in shrimp nets
The Last Word
"They killed turtles, distributed the meat in the interior, dried calipee for sale, and mined the eggs in masses. Three years ago I realized that I had heard no definite report of an arribada since some time in the latter part of the 1950s. Now I have just finished canvassing every possible source of information, and it adds up to the dismal certainty that no arribada has been seen for at least seven years. Two or three skipped years might be atrtibuted to chance, because ninety miles is a long beach and there are not really many people there. Now, however, there is no escaping the snowballed evidence that the great arrivals have failed. Cotorras still straggle ashore along the Tamaulipas coast, but they are few and scattered. The fabulous conclaves of former years have gone the way of a thousand other sea turtle colonies before them."
Archie Carr
The Sea Turtle - So Excellent A Fishe
p. 157
1986, University of Texas Press
Last modified 04/01/24
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Comments (4)
June Shanahan said
at 5:02 pm on May 14, 2009
I know somebody that has 100% extra credit for science! One of my favorite parts of this project is that you thought of it on your own and created it. You didn't do it for the grade. :-) That means you did it for the love of learning! Your sea turtle wiki project is amazing, Sean. Am I allowed to share it with Professor Nancy in North Carolina?
sean said
at 8:13 am on May 21, 2009
Yes you are.
sean said
at 8:11 am on May 27, 2009
My favorite one is the kimps ridley.
June Shanahan said
at 7:57 pm on May 27, 2009
TWO SPECIAL WORDS, JUST FOR YOU: Extra Credit!
TWO MORE: You're amazing!
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