Endangered Sea Turtles 101

Leatherback Sea Turtles

Credit Seeturtles

The largest of all sea turtles, and one of the largest reptiles on earth, the leatherback turtle ranges in size from 4-8 feet in length (1.2 - 2.4 meters) and weighs between 500-2,000 pounds (225 - 900 kg). The average adult measures in between 5-6 feet (1.5 - 1.8 m) and weighs 600-800 pounds (270 - 360 kg).

The oldest of all sea turtle species, it has been around for more than 150 million years! They survived the extinction of the dinosaurs and thrived until the last several decades when human interactions have taken a major toll.


  • Leatherbacks can consume twice their own body weight in prey per day, feeding exclusively on soft-bodied invertebrates like jellyfish and tunicates. Learn more about their diet.

  • They have downward curving spines (also known as papillae) in their mouth and throat which help them to capture and swallow their prey.

  • Unlike all other sea turtles, these giants do not possess a carapace (shell) covered with hard scales, also known as scutes. Their smooth, leathery skin covers a flexible matrix of bone. This specialized, flexible carapace allows them to dive to great depths unlike other species.

  • Their widespread distribution and ability to tolerate cold water are due to thermoregulatory adaptations (called gigantothermy) which allow them to maintain their core body temperature.

  • They are considered Vulnerable around the world by the IUCN Red List and listed as Endangered in the US.

  • Their scientific name is Dermochelys coriacea.

Green Sea Turtles

The green turtle is the second largest after the leatherback. They can weigh up to 500 lbs (225 kg) and reach four feet (1.2 m) in length. The adult is an herbivore, dining on sea grasses, seaweeds, algae and other forms of marine plant life. Their beak is sharp and finely serrated, perfectly adapted for grazing in seagrass beds and scraping algae off of hard surfaces.

This species is the only one to come on shore regularly to bask. Basking only occurs in Hawaii, particularly the Northwestern Hawaiian Island chain, the Galapagos Islands, and in some areas of Australia.


  • These turtles are believed to improve the health of seagrass beds and associated microhabitats. They will graze the beds, taking off the tops of leaf blades, while avoiding the roots. The seagrass will grow healthier and faster with a daily trim! Learn about their diet.

  • Greens in the Eastern Pacific are called Pacific Black turtles and some researchers believe they are a separate species. Their coloration is not black, but their skin pigmentation is darker than other green turtles, making them appear darker overall. They are also smaller and their carapace is slightly different in shape.

  • Their name comes from the color of their fat, not their shell, as commonly believed.

  • They are listed as Endangered in the US and around the world by the IUCN Red List.

  • Their scientific name is Chelonia mydas.


Hawksbill Sea Turtles

Considered by many to be the most beautiful of sea turtles for their colorful shells, the hawksbill is found in tropical waters around the world. They spend their time in coral reefs, rocky areas, lagoons, mangroves, oceanic islands, and shallow coastal areas.

Named for its narrow head and sharp, bird-like beak, hawksbills can reach into cracks and crevices of coral reefs looking for food. Their diet is very specialized, feeding almost exclusively on sponges. One of the smaller turtles, adults weigh between 100-200 pounds (45 - 90 kg) and reach 2-3 feet (roughly .5 to 1 meter) in length. Learn more about their diet.


  • These turtles are solitary nesters, nesting in low densities on small scattered beaches. Adult females are well adapted for crawling over reefs and rocky areas to reach secluded nesting sites.

  • On average, they nest roughly 4 times per season at 2 week intervals and lay around 140 eggs per nest. Nests however, may contain over 200 eggs!

  • Hawksbills are considered Critically Endangered around the world by the IUCN Red List and are listed as Endangered in the US. Some researchers believe the Eastern Pacific hawksbill is likely the most endangered sea turtle population worldwide.

  • Their scientific name is Eretmochelys imbricata.


This species inhabits tropical and some sub-tropical regions in the Atlantic, Pacific, and Indian Oceans. The largest populations occur in the Caribbean Sea, the Seychelles, Indonesia, Mexico, and Australia. Hawksbills are not found in the Mediterranean and few are found in US waters; only a handful nest in Florida each year


Loggerhead Sea Turtles

One of the larger species of sea turtles, the loggerhead turtle ranges from 200-400 pounds (90 - 180 kg) and up to 4 feet in length (1.2 meters). They occur throughout temperate and tropical regions of the Pacific, Indian, and Atlantic Oceans.

One of the most abundant of the species found in the US, they are named for their large head and strong crushing jaw (right) which enables them to eat hard-shelled prey such as crabs, conchs, and whelks. 


  • One population of these turtles nests in Japan and migrates across the entire Pacific Ocean to the rich feeding grounds off the coast of Baja California Sur, Mexico, where they spend several years foraging and maturing.

  • In the US, most of their nests are laid in Florida, however in the last decade the number of nests in Florida has declined by 40%.

  • They are listed as Vulnerable around the world by the IUCN Red List and Threatened in the US.

  • Their scientific name is Caretta caretta.


Loggerheads are found in every ocean around the world. Only leatherbacks have a wider distribution. The largest concentration of nesting occurs on Masirah Island off the coast of Oman in the Middle East. In the Pacific, their main nesting grounds include Japan and Australia. In the Atlantic, the main concentration occurs in Florida. They are the most common species in the Mediterranean, nesting on beaches in Greece, Turkey, and Israel.


Their biggest threat is entanglement in fishing gear (also known as “bycatch”) in commercial fishing gear, including trawls, longlines, gillnets, and traps and pots. In the US trawl fishery, devices called TED’s, or Turtle Excluder Devices are required by law. These devices allow sea turtles to escape out of the nets, however in other parts of the world these devices are not regulated and they continue to be caught.

Scientific studies co-authored by SEE Turtles co-founder Dr. Wallace J. Nichols have shown the waters off Baja California Sur, Mexico to have among the highest rates of turtle by catch in the world. In some parts of the world, they are also consumed for their meat and eggs. Beachfront development is also a threat, particularly in the Mediterranean.


Olive Ridley Sea Turtles

The second smallest after the Kemp’s ridley, the olive ridley turtles weigh between 75-100 pounds (34 - 45 kg) and reach 2-2 ½ feet (roughly .6 m) in length. They are named for their pale green carapace, or shell and are the most abundant of sea turtle species.  

Like the Kemp’s ridley, nest in masses referred to as arribadas. During arribadas, thousands of females may nest over the course of a few days to a few weeks. Adults reach sexual maturity around the age of 15 years.


  • There are only a few places in the world where olive ridley arribadas occur (see Distribution below for sites). In other parts of the world, they are solitary nesters.

  • Though arribadas are not well understood, the timing is thought to coincide with weather events such as strong winds or cloudy days, or with moon and tide cycles. The turtles congregate in large groups offshore of nesting beaches and then simultaneously come ashore to nest. Females may remain offshore near nesting beaches throughout the nesting season.

  • These turtles are omnivores, eating a variety of prey including crabs, shrimp, lobster, urchins, jellies, algae, and fish. In Baja California, Mexico, their preferred prey is the red crab which is abundant in offshore waters. 

  • Despite their relative abundance in comparison to other sea turtles, this species is considered Vulnerable by the IUCN Red List and is listed as Threatened in the US.

  • Although they are the most abundant species, their numbers have decreased by approximately 50 percent since the 1960’s. Their scientific name is Lepidochelys olivacea.


Olive ridleys occur globally and are found mainly in tropical regions of the Pacific, Indian, and Southern Atlantic Oceans. They are primarily pelagic, spending much of their life in the open ocean, but may also inhabit continental shelf areas and venture into bays and estuaries.

Arribadas occur in Mexico, Nicaragua, Costa Rica, Panama, Australia, parts of Africa, and a few beaches along the coast of India. The largest ones occur in Costa Rica, Mexico, and India. Nicaragua has a significant beach in La Flor Wildlife Refuge. Other solitary nesting areas include Guatemala, Brazil, Myanmar, Malaysia, and Pakistan. Worldwide, they nest in approximately 40 countries.


Threats to olive ridleys include the direct harvest of turtles and eggs for human consumption, entanglement of turtles in commercial fishing gear, and coastal development.


Kemp's Ridley Sea Turtles

Until recently, the endangered Kemp’s ridley turtle was on the brink of extinction in the 1960's. Thanks to strict protection laws which protected their nesting beaches in Mexico and reduced accidental capture in fishing gear, the species has begun a slow, but steady comeback from a previous low of only 200 nesting individuals in the 1980’s, to an estimated 7,000 - 9,000 individuals today.

These are the smallest of the seven sea turtle species, weighing between 75-100 pounds (35 - 45 kg) and measuring approximately 2 feet (.6 m) in length.


  • This is the only species that nests primarily during the day. They also nest in mass similar to their relative the olive ridley (also known as an arribada).

  • They possess a triangular shaped heads with hooked beaks and strong jaws. They inhabit nearshore habitats where they forage for their favorite prey, crabs. They also eat fish, jellies, shrimp, and a variety of molluscs. 

  • They are considered Critically Endangered around the world by the IUCN Red List and listed as Endangered in the US.

  • Kemp’s ridleys reach sexual maturity between 10-15 years of age which is significantly younger than most of the other species.

  • Their scientific name is Lepidochelys kempii.


In the US, these turtles are found in the Gulf of Mexico and along the Atlantic coast as far north as Nova Scotia. The primary nesting grounds in Mexico are at Rancho Nuevo, in the state of Tamaulipas, and in Texas along the Padre Island National Seashore. A small number have also nested further north along the Texas coast. However, 95% of all nesting occurs in Mexico in the state of Tamaulipas.


Their population today is a fraction of the population recorded in the 1940’s. The demise of the population is attributed to human interactions, including the hunting for their meat and eggs. Entanglement in fishing gear also poses an enormous threat for this species. Bottom trawling, longline, and gillnet fisheries are all responsible for a large number of deaths every year.


Flatback Turtles

The flatback turtle is named after its flat carapace, or shell, which is unlike the curved shell of other sea turtle species. The carapace is pale grayish-green in color with the outer margins distinctly upturned. An adult flatback weighs 200 pounds and is approximately 3 feet in length. They have the smallest distribution of all the species and breed and nest only in Australia.


Flatbacks are preyed upon by Saltwater crocodiles, the largest reptile on earth. Adult females have been observed being attacked by crocs while attempting to nest.Despite its small range and non-migratory behavior, until now this has been the least studied of the sea turtle species, perhaps due in part to the remoteness of much of their habitat.


  • In comparison to other sea turtle species that lay 100-200 eggs per nest, this species lays an average of 50 per nest. Their eggs and hatchlings however, are proportionally larger than other species, which may aid hatchlings in evading predators.

  • The flatback is an omnivore, feeding on a variety of prey including sea cucumbers, jellies, soft corals, shrimp, crabs, molluscs, fish, and seaweed. Learn more about their diet.

  • They are listed as Vulnerable under the Australian Commonwealth’s Endangered Species Protection Act. They are listed as data deficient by the IUCN Red List.

  • Their scientific name is Natator depressus.


The flatback has the smallest geographic range of the seven sea turtle species. Their distribution is restricted to tropical regions of the continental shelf and coastal waters of Northern Australia, Southern Indonesia, and Southern Papua New Guinea. They do not have an oceanic phase or undertake long, open ocean migrations like other sea turtles, and are usually found in waters less than 200 feet in depth.

Breeding and nesting only occur in Australia with the largest concentration of females nesting on Crab Island in the NE Gulf of Carpentaria in Queensland. Primary nesting beaches are distributed from East to West across Queensland, the Northern Territory, and Western Australia.


Threats to this species include direct harvest for meat and eggs, entanglement in fishing gear, destruction of nesting beaches from coastal development, pollution, and destruction of feeding habitat (coral reefs and shallow nearshore areas). Dingos and foxes once posed a significant threat to their nests but thanks to predator control programs, this threat has been greatly reduced.

Nests and hatchlings however are preyed upon by the Sand Monitor lizard, birds-including Night Herons and Pelicans, and feral pigs. In some areas, feral pigs consume almost all their nests.