Cheloniidae is a family that contains all but one of the marine turtles. The only turtle that isn’t part of Cheloniidae is the leatherback sea turtle. Common characteristics of the chelonians within this family include rounded wide streamlined shells, flattened carapaces, and paddle-like flippers.
Species within the Cheloniidae family include Kemp’s ridley, olive ridley, flatback, hawksbill, loggerhead, and green turtle. These are grouped into five genera.
They are commonly also referred to as cheloniid sea turtles. These are the only turtles whose front limbs are more powerful than their hind limbs.
Cheloniidae was first described and named by Nicolaus Michael Oppeil, a German naturalist, in 1811.
Cheloniids are huge turtles with a maximum length of 84 inches (213 cm), which is the length of the loggerhead, and a minimum length of 28 inches (71 cm), which is the length of the olive ridley. All cheloniids have heart-shaped or oval carapaces.
Members of the family Cheloniidae are unable to retract their heads into their shells.
Cheloniidae are omnivorous and feed on vegetation, fish, algae, crustaceans, mollusks, cnidarians (including jellyfish), and sponges.
Most cheloniids are endangered and require immediate conservation. This is due to the reduction of nesting habitats, the harvesting of the turtle and the eggs for food, bycatch in fishing gear, and pollution.
The lifespan of cheloniids is not well known and there is little information on this. However, these turtles are long-lived living to 50 to 70 years on average.
Cheloniids can be found in all the oceans of the world apart from polar and subpolar regions. The leatherback is the only sea turtle that can be found in cold waters. The flatback can be found on the northern coast of Australia.
Cheloniidae start life in the pelagic zone where they float along with the major current systems of the ocean. Adults migrate between oceanic waters and nesting habitats.
Interestingly, the COVID-19 pandemic led to an increase in nesting all over the world. This is because there were fewer people on the nesting beaches.
Cheloniidae exhibit temperature-dependent sex determination. Here the sex of the hatchlings is determined by the incubation temperature of the egg.
Table of Contents
Species Within The Family Cheloniidae
Lepidochelys
Species within the genus Lepidochelys are the Kemp’s Ridley (Lepidochelys kempii) and the Olive Ridley (Lepidochelys olivacea).
1. Kemp’s Ridley Sea Turtle
- Scientific Name: Lepidochelys kempii
- Length: 22 to 30 inches (55 to 75 cm)
- Mass: 66 to 110 lb (30 to 50 kg)
- Lifespan: 30 to 50 years
- IUCN Red List Status: Critically Endangered
The Kemp’s ridley is considered the smallest sea turtle with an average adult carapace length of 22 to 33 inches and with an average adult mass of 66 to 110 lbs. While the turtle is considered small for a sea turtle it is still quite large for a turtle in general.
The species have a heart-shaped and streamlined shell which allows it to swim effortlessly through the water. You can say the shell is hydrodynamic. The carapace is gray in coloration while the plastron is off-white or yellowish in coloration.
As with all other sea turtles, the Kemp’s ridley has flippers instead of feet. This enables them to be great swimmers. However, the flippers are ill-adapted for movement on land.
The Kemp’s ridley is aquatic so this isn’t a problem. Females however come to shore to nest while on land, their movement is slow and labored.
Kemp’s ridley is an omnivore that feeds on the following animal foods: jellyfish, crabs, sea urchins, mollusks, and shrimp. They are also known to feed on aquatic vegetation such as seaweed and algae.
The lifespan of this turtle is hard to figure out as there is little research on their lifespans. However, it is estimated that the species have a lifespan of 30 to 50 years once they reach maturity.
The species is estimated to reach maturity at 10 to 12 years. Upon reaching maturity, the species mate and reproduce. Kemp’s ridley has a generation length of 18 years which is the average age of parents.
In terms of behavior, Kemp’s ridley is a strong swimmer that lives solely in saltwater, particularly in the sea. The species are migratory and travel thousands of miles.
The species is located in the Atlantic ocean from the North American east coast to western Europe from the United Kingdom to the western Iberian coast. The species breed on the North American east coast from Mexico to the United States.
It has been calculated that the current world population of the species is under 25,000. There are no known subpopulations, just one population. The species primarily nest in the Gulf of Mexico near Rancho Nuevo, a small town in Mexico.
The species can be found in Appendix I of CITES and Annexes IV of the EC Habitats Directive. Appendix I of CITES protects the species and all products made from the species or its body parts from being transported internationally, imported, and exported.
Annexes IV of the EC Habitats Directive protects the species from being hunted or exploited in Europe.
2. Olive Ridley Sea Turtle
- Scientific Name: Lepidochelys olivacea
- Length: 23 to 29 inches (58 to 74 cm)
- Mass: 66 to 110 lb (30 to 50 kg)
- Lifespan: 30 to 50 years
- IUCN Red List Status: Vulnerable
The olive ridley can be found mostly in the tropics where they nest. These turtles migrate from subtropical areas to tropical areas.
The species can be found in the tropics and subtropics of the Indian Ocean, Pacific Ocean, and the Southern Atlantic ocean. The species is generally between latitudes 40 degrees south and 40 degrees north.
In North America, they can be found in the Caribbean on the beaches of countries such as Nicaragua (La Flor and Chacocente) and Panama (Isla Cañas and the Southern Zone of Veraguas) and along the Gulf of California.
The biggest nesting habitat of the species is the BhitarKanika Wildlife Sanctuary in India.
The species is usually found within 9 miles of the shore. They feed and bask in neritic waters. Regardless, they can also be found in the open sea.
Olive ridleys are quite large for a turtle but are quite small for a sea turtle. They are about the same size as the Kemp’s ridley which they are closely related.
Their carapace is heart-shaped and olive in color. The olive ridley reaches a length of 30 inches and a mass of 100 lbs. With males, the tail extends past the carapace. It isn’t so with females.
Females reach reproductive maturity at a length of 60 cm. Mating occurs in the spring and early summer. Females store sperm to be used throughout the entire breeding season.
Mating occurs within breeding habitats but offshore the nesting beaches. Gravid females normally return to natal beaches to mate and nest. Females generally lay eggs at the night.
The olive ridley is known for the phenomenon called arribada. Here hundreds and even thousands of gravid females come to shore to nest at the same time.
In Nicaragua, the arribada can be observed at Chacocente, La Flor, and Corazon from July to October.
Olive ridleys are primarily carnivorous and feed on jellyfish, fish, crabs, shrimps, snails, and other foods. The species has also been observed to be cannibalistic. Similar to Kemp’s ridley turtles, the olive ridley turtles also feed on plant material such as algae.
The olive ridley is considered Vulnerable on the IUCN Red List. They are also listed in Appendix I of CITES, and the Convention on Migratory Species.
Threats to the species include egg harvest in an unsustainable manner, the illegal take of adult turtles, bycatch in fisheries such as gillnet, hook and line fisheries, purse seines, longline fisheries, and trawl fisheries.
3. Hawksbill Sea Turtle
- Scientific Name: Eretmochelys imbricata
- Length: 25 to 45 inches (63 to 114 cm)
- Mass: 79 to 280 lb (36 to 137 kg)
- Lifespan: 30 to 50 years
- IUCN Red List Status: Critically Endangered
Hawksbills can be found mainly in the tropics of the Pacific and Atlantic oceans.
However, it can also be found in the Indian ocean. The species is migratory and has been found in a broad range of habitats.
During the neritic developmental phase of the turtle’s life which happens once the species reaches a carapace length of 20 to 30 cm, the species can be found in hard-bottom habitats such as coral reefs, mangrove bays and creeks, algal beds, and seagrass. Older hawksbills can be found in deeper sites. These are the foraging habitats of the turtle.
Upon reaching reproductive maturity, the species migrate between breeding habitats and foraging habitats. This occurs every two to three years. Females are known to generally return to breeding habitats where they hatched.
The hawksbill turtle is named after its V-shaped head which gives them the appearance of a hawk’s bill. The carapace of hawkbill turtles starts out heart-shaped but as they grow, this carapace elongates.
The hawksbill can be easily distinguished from other sea turtles by their elongated moths that look like a hawk’s beak, the two claws on their front limbs, and the two pairs of prefrontal scales on their heads.
The hawksbill isn’t that large when compared to other sea turtles. The species has an average mass of 80 kg or 176 lb and an average length of 34 inches or 87 centimeters. Males have thicker tails, longer claws, more concave plastrons, and brighter coloration.
When hatched, these turtles have a mass of 13.5 to 20 grams and a carapace length of 4.2 cm. The sex of the hatchlings is determined by the temperature of the nest.
The lifespan of the species is unknown although it is believed to be above 20 years, perhaps between 30 and 50 years.
The hawksbill is diurnal and solitary. They forage for food during the day.
The species is predominantly carnivorous and feeds mostly on sponges. They also feed on sea jellies and other coelenterates. Other foods they are known to eat are crustaceans, fish, mollusks, marine algae, fruits, wood, steers, bark, and leaves.
The species is considered critically endangered on the IUCN Red List. They are also listed in Appendix I of CITES, Appendices I and II of the Convention on Migratory Species, and Annexes IV of the EC Habitats Directive.
The collection of the species’ eggs and the harvesting of the species for their meat and shell are prohibited all around the world. Also, the importation and exportation of any product containing or made from parts of the turtle are also prohibited.
4. Green Sea Turtle
- Scientific Name: Chelonia mydas
- Length: 39 to 47 inches (100 to 120 cm)
- Mass: 330 to 441 lb (120 to 200 kg)
- Lifespan: 75 years
- IUCN Red List Status: Endangered
The green turtle is named after the greenish color of the turtle’s subdermal fat and not the turtle’s color itself. The turtle is also known as the black turtle which is a name derived from its coloration (especially when young) which is dark. Hatchlings and juveniles are black in coloration but the color lightens with time.
The green turtle is endemic to all the oceans of the world except for the Arctic Ocean. This turtle is generally found in the tropics. They are generally found in the northern Indian Ocean, the Atlantic Ocean, the Pacific Ocean, and the Mediterranean Sea.
The green turtle is migratory like the hawksbill and can travel over thousands of miles from foraging habitats to breeding habitats. The species is known to nest in at least 80 countries and is also known to inhabit the coastal areas of at least 140 countries.
The habitat of the species varies and depends on the age of the turtle. The turtle starts life floating in the major current systems of the oceans they live in.
Subadults are known to live in shallow coastal waters rich in algae and seagrass which they feed on. As adults, the turtle travels from their foraging habitats to their breeding habitats.
These migrations cover thousands of miles. When not migrating, the species can be found in coastal waters where they feed.
The species breed every two to four years from June to September. The species is known to return to their natal beaches to reproduce. Although they may nest on a different beach that has similar sand color and texture as that of their natal beaches.
The temperature of the nesting site determines the sex of the turtle. Nests with temperatures below 83.3 degrees Fahrenheit (28.5 degrees Celsius) produce more males and nests with temperatures above 86.5 degrees Fahrenheit (30.3 degrees Celsius) produce more females.
The green turtle is an endangered species that faces several threats. Most of which are caused by humans.
The main threats that the species face include nesting habitat degradation caused by beach armoring and re-nourishment, sand extraction, and building construction; bycatch in fisheries such as gillnet, hook and line fisheries, purse seines, longline fisheries, and trawl fisheries; and the collection of the eggs.
As a result of the threatening nature of the species, the green turtle is listed in Appendix I of CITES and the EC Habitats Directive.
Appendix I of CITES protects the species and all products made from the species or its body parts from being transported internationally, imported, and exported. The EC Habitats Directive protects the species in Europe.
5. Flatback Sea Turtle
- Scientific Name: Natator depressus
- Length: 30 to 38 inches (76 to 96 cm)
- Mass: 154 lb (70 kg)
- Lifespan: 100 years
- IUCN Red List Status: Data Deficient
The flatback is known to inhabit the waters north of Australia. They can be found in the coastal waters of Papua new guinea and the Tropic of Capricorn (from Australia to the Tropic of Capricorn) where they feed. The species has the most limited geographic range of any sea turtle species.
The flatback is found close to shore – in shallow coastal waters. They can be found in marine water bodies with soft bottoms unlike other species of the family Cheloniidae such as Eretmochelys imbricata that inhabit hard-bottom habitats such as coral reefs. Flatback has never been found in coral reefs.
The flatback is large for a turtle but moderately sized with the family Cheloniidae. These turtles are larger than ridley turtles but are smaller than hawksbills, green turtles, and loggerheads.
Adult females are generally larger than adult males. However, adult males possess longer tails.
The carapace and the plastron of the flatback are quite thin and they injure easily. This is why the flatback prefers soft-bottom habitats as rocky hard bottom habitats can cause severe injuries to the turtle.
The carapace is olive green and the plastron is off-white or yellowish in coloration.
The turtle is predominantly carnivorous and rarely eats plant material. The species feed on prawns, jellyfish, bryozoans, mollusks, and sea cucumbers.
The flatback doesn’t have many predators even as hatchlings and juveniles. Two known predators are sharks and killer whales.
The flatbacks reach reproductive maturity at age 7 to 50 years. The breeding season starts in November and ends in December. Females nest on the northern shores of Australia.
A major nesting site of the turtle is Mon Repos which is northwest of Bundaberg in Queensland. This area supports one of the largest nesting concentrations, if not the largest, in Australia.
Unlike the other turtles, the flatback hatchlings do not live in the open ocean and as such do not float in the major current systems of the oceans. It is unknown where hatchlings and juveniles do during this time.
The species do not migrate between feeding and breeding habitats as they mostly remain close to shore their entire lives.
The flatbacks are long-lived turtles that can reach an age of 100 years in the wild.
The species has no special status on CITES. The species carry a Data Deficient status on the IUCN Red List.
The species is believed to be the least endangered sea turtle. The species are rarely accidentally caught in fishing gear as they stay close to the coast.
6. Loggerhead Sea Turtle
- Scientific Name: Caretta caretta
- Length: 33 to 39 inches (85 to 100 cm)
- Mass: 170 to 1200 lb (77 to 545 kg)
- Lifespan: 62 years
- IUCN Red List Status: Vulnerable
The loggerhead can be found globally in the Atlantic Ocean, Indian Ocean, and the Pacific Ocean.
It is also prevalent in the Mediterranean Sea. This species is found mainly within the subtropics and the temperate regions of the world.
The loggerhead has 10 different subpopulations. A subpopulation is determined by geographic descriptions as well as biological descriptions.
The 10 subpopulations include South Pacific Ocean, North Pacific Ocean, SouthWest Indian Ocean, SouthEast Indian Ocean, North West Indian Ocean, North East Indian Ocean, Mediterranean Sea, SouthWest Atlantic Ocean, North East Atlantic Ocean, and NorthWest Atlantic Ocean.
The species is known as the loggerhead because of their large heads. The loggerhead is the largest hard-shelled sea turtle and the second largest sea turtle.
The species like most sea turtles are migratory and can be found in a wide range of habitats depending on their age. Hatchlings float in the major current systems of the oceans.
At this stage, they live in the open ocean. After 4 to 19 years, loggerheads are known to live in shallow coastal waters rich in benthic prey or epipelagic prey which they feed on.
As adults, the turtle travels from their foraging habitats to their breeding habitats.
These migrations cover thousands of miles. When not migrating, the species can be found in coastal waters where they feed.
The species attain reproductive maturity at age 10 to 39 with 30 years being considered the average age of maturity or greater than it. Breeding occurs mostly from May to July although members of the species breed throughout the year.
The lifespan of the species is considered to be 30 to 62 years. The generation length is 45 years. The generation length is the average age of the parents.
The loggerhead faces several threats. Threats created by human activities.
The main threats are the collection of the turtles and their eggs for human consumption, fisheries bycatch, coastal development, and pollution and pathogens such as fibropapilloma virus. Climate change is expected to significantly impact the species and their habitats.
The loggerhead is listed in Appendix I of CITES and the EC Habitats Directive. Appendix I of CITES protects the species and all products made from the species or its body parts from being transported internationally, imported, and exported.
On the EC Habitats Directive, the species is listed in Annexes II and IV. the turtle is the only sea turtle in Annex II of the Habitats Directive.
Frequently Asked Questions
Which cheloniids are endangered?
Cheloniidae is generally threatened. All but one xx are considered threatened with an IUCN status of at least Vulnerable. Lepidochelys kempii (Kemp’s ridley) is considered critically endangered.
Eretmochelys imbricata (hawksbill) is considered critically endangered. And Chelonia mydas (green turtle) is considered endangered.
In all, three of the six extant species of the family Cheloniidae are considered endangered. The endangered nature of the family means that there needs to be the implementation of conservation measures to ensure the survival of the family in the wild.
What are the biggest threats that Cheloniidae faces?
Cheloniidae faces several threats. Most of which are caused by humans.
The main threats that the family face includes nesting habitat degradation caused by beach armoring and re-nourishment, sand extraction, and building construction; bycatch in fisheries such as gillnet, hook and line fisheries, purse seines, longline fisheries, and trawl fisheries; and the collection of the eggs.
In many communities around the world where cheloniids nest, the eggs are collected for food as sea turtle eggs are an important component of their cuisine. In some nesting habitats, 100% of eggs are collected from the nests.
In countries such as Panama, coastal communities are allowed to collect eggs sustainably in exchange for helping with conservation efforts by the government.
What other families is Cheloniidae closely related to?
Two families can be said to be closely related to Cheloniidae and these are Dermochelyidae and Ctenochelyidae.
Dermochelyidae is a family that includes the only other extant sea turtle apart from the ones on this page and that is the leatherback sea turtle.
Ctenochelyidae includes the genus Ctenochelys. This genus includes two extinct sea turtles that existed about 100 million years ago during the Cretaceous period.
Is it legal to own cheloniids as pets?
It is illegal to keep a cheloniid as a pet. These turtles are almost impossible to care for in captivity and require large water parks such as Aquatica.
Conclusion
All but one sea turtle are members of the family Cheloniidae which is made up of five genera and six species.
The species include Kemp’s ridley, olive ridley, flatback, hawksbill, loggerhead, and green turtle (also known as the black turtle). These turtles are together referred to as cheloniid sea turtles.
These turtles are huge with a maximum length of 84 inches and a minimum length of 28 inches.
All species within the family are omnivorous and feed on vegetation, fish, algae, crustaceans, mollusks, cnidarians (including jellyfish), and sponges.
Sadly cheloniids are mostly endangered and require immediate conservative actions. Threats they face include habitat degradation caused by beach development, collection of the turtles and their eggs, bycatch, marine debris, pollution including oil spills, and climate change.