A Sea Turtle Fanatic's Guide: Meet the 6 Sea Turtle Species Living on Australia's Great Barrier Reef!

Last December, the ocean documentary Sea Turtle Rescue, starring Eddie Peng, made its debut. The film was produced by WildAid in partnership with the China Sea Turtle Conservation Alliance and Youku, with award-winning cinematographer Andrew Wegst serving as director. Across three episodes, viewers follow Eddie Peng to Costa Rica, Ecuador, Malaysia, Indonesia, the Philippines, and China, meeting a remarkable group of "sea turtle warriors" and learning what sea turtle conservation means for both humanity and the environment.

After watching this vivid and captivating documentary, it got the editor thinking about just how many sea turtles call the Great Barrier Reef home.

In fact, six of the seven known sea turtle species are residents of the Great Barrier Reef. Some roam across multiple reef systems, while others are rare visitors.

Queensland, home of the Great Barrier Reef, launched a sea turtle research program 30 years ago. Thanks to the marine scientists, Indigenous communities, and fishermen who dedicated their efforts to this cause, our understanding and conservation of sea turtles have advanced enormously.

Today, let's dive into the world of our sea turtle friends and get to know the species living on the Great Barrier Reef!

Species #1: Green Sea Turtle

The Green Sea Turtle is arguably the easiest sea turtle to encounter on the Great Barrier Reef. Their shells are generally smooth with a raised, dome-like shape, olive-green in colour, occasionally with brown, reddish-brown, or black highlights. Adult carapace length can reach 0.9 m to 1.2 m, and they can weigh over 100 kg.

Green Sea Turtles are found in tropical and subtropical waters worldwide. They reproduce in relatively large numbers and love to frequent warm, shallow reef areas. Most adult Green Sea Turtles are herbivores, feeding on algae, seagrass, and jellyfish.

Within the Great Barrier Reef World Heritage Area, there are two genetically distinct Green Sea Turtle populations — one in the south and one in the north. The southern population sees an average of 8,000 turtles come ashore to nest each year, while the remote yet famous Rain Island in the north attracts up to 30,000 female turtles annually, making it one of the most spectacular sea turtle nesting sites in the world.

Their migration routes are also remarkably varied — every year, Green Sea Turtles travel between Indonesia, Papua New Guinea, Vanuatu, and the Great Barrier Reef.

Green Sea Turtle Quick Facts

Scientific name: Chelonia mydas Nesting season: Late October to February Nesting age: 45 years Clutch size: Average 115 Hatching period: December to May Hatching success rate: 84% Egg and hatchling predators: Crabs, herons, dingoes, giant trevally, sharks, and other fish

Species #2: Loggerhead Turtle

You might not guess it from the Chinese name, but the English name "loggerhead" comes directly from this turtle's notably large head. The Loggerhead Turtle has a powerful jaw capable of crushing shells and molluscs such as crabs, sea urchins, and jellyfish — all staples of its diet. They prefer to forage around coral reefs, continental shelves, and shallow sargassum beds.

Adult Loggerhead Turtles are brown, with shells that can show light brown, reddish-brown, or black tones on top, and are typically yellow underneath. They measure 1–2 m in length and generally weigh over 100 kg. Juveniles usually have dark brown shells and pale brown plastrons.

Australian waters are home to two genetically distinct Loggerhead Turtle populations — one along the east coast and one along the west coast. Research shows that populations nesting and foraging on the Great Barrier Reef migrate to areas including Arnhem Land, Torres Strait, and Papua New Guinea.

Female Loggerhead numbers once dropped to below 1,000 individuals, placing the species at risk of extinction due to increased mortality. This led to the species being listed on the IUCN Red List of Threatened Species in 2012 as Endangered. In response, the Queensland Government made turtle excluder devices mandatory for fisheries from 2001, and nesting numbers have since shown an encouraging recovery.

Loggerhead Turtle Quick Facts

Scientific name: Caretta caretta Nesting season: Late October to March, peaking in December Nesting age: 20–25 years Clutch size: Average 127 Hatching period: December to April Hatching success rate: 80% Egg and hatchling predators: Foxes, kookaburras, crows, seagulls, raptors, reef egrets, ghost crabs, giant trevally, sharks, and other fish

Species #3: Hawksbill Turtle

The Hawksbill Turtle is perhaps the most iconic of all sea turtles. It has a beautiful, intricate pattern of black and brown markings, with a distinctively narrow head and a sharp, beak-like mouth. It typically measures around 0.6 m, with larger individuals reaching up to 1.6 m, and average weight ranging from 46 to 70 kg.

Hawksbill Turtles can be found across the globe, typically appearing in tidal and sub-tidal coral reefs in tropical and subtropical regions. Their diet includes invertebrates such as jellyfish, sea anemones, shrimp, crabs, and molluscs, as well as fish and algae.

In ancient times, Hawksbill shells were prized for making ornamental jewellery and accessories. Today, overharvesting has pushed the species to the brink of extinction, with populations nearly vanished from China's nearshore waters. No demand, no killing — we urge everyone to take action and refuse all wildlife products.

Hawksbill Turtles have three major nesting regions in Australia: the northern Great Barrier Reef (thousands of nesting females), northeastern Arnhem Land (approximately 2,000 individuals), and Western Australia (thousands of individuals). In particular, the entire northernmost area of the Great Barrier Reef and Torres Strait region plays a critically important role in international Hawksbill conservation, as populations are declining in many parts of the world.

Research by marine scientists indicates that Hawksbill Turtles nesting on the Great Barrier Reef migrate to Indonesia, Papua New Guinea, the Solomon Islands, and Vanuatu.

Hawksbill Turtle Quick Facts

Scientific name: Eretmochelys imbricata Nesting season: Year-round, concentrated November–February, peaking in January Nesting age: 30–35 years Clutch size: Average 122 Hatching period: Year-round, concentrated February–April Hatching success rate: 79% Egg and hatchling predators: Seagulls, reef egrets, ghost crabs, crocodiles, fish, sharks, crabs, and dingoes

Species #4: Flatback Turtle

True to its name, the Flatback Turtle has a low, distinctly flat carapace with thin, waxy marginal scutes. Adult Flatback Turtles are typically olive-grey on top with a white plastron. They can reach up to 1 m in length and weigh up to 80 kg.

The Flatback Turtle is essentially Australia's own sea turtle — they are found exclusively on Australia's continental shelf and feed mainly on soft corals, sea pens, and jellyfish. Although they do venture into Indonesian and Papua New Guinean waters to forage, they nest only on Australian shores. This is because Flatback hatchlings live solely in coastal waters and never venture into the open ocean.

All known Flatback Turtle nesting sites are in Australia. While researchers are not yet certain about population trends, studies indicate that Flatback Turtle nesting numbers along Australia's east coast, including the Great Barrier Reef, are relatively stable.

Flatback Turtle Quick Facts

Scientific name: Natator depressus Nesting season: November–February Nesting age: 20 years Clutch size: Average 54 Hatching period: January–April Hatching success rate: 80% Egg and hatchling predators: Pelicans, ghost crabs, crocodiles, and sharks

Species #5: Olive Ridley Turtle

The Olive Ridley Turtle is listed as Endangered by the IUCN and is the smallest of all sea turtle species, measuring 0.6–0.7 m in length and weighing approximately 34–45 kg. Its shell, when viewed from above, is distinctively round — almost heart-shaped. Adult Olive Ridley Turtles range in colour from grey to olive-grey, while hatchlings are black.

Olive Ridley Turtles are commonly found in tropical and subtropical waters of the Pacific and Indian Oceans. In Australia, they are largely confined to the protected shallow waters of southern Queensland or Joseph Bonaparte Gulf in Western Australia. They typically prey on molluscs, jellyfish, and other invertebrates, occasionally eating fish eggs, and also consume plant matter.

In Australia, there are two main Olive Ridley nesting areas. One is in the Northern Territory, with approximately 1,000 nesting females per year; the other is in the Gulf of Carpentaria above Queensland, with fewer than 100 nesting females annually. Although Olive Ridley Turtles do forage within the Great Barrier Reef World Heritage Area, no nesting by this species has been recorded there.

Because Olive Ridley Turtles are uncommon on the Great Barrier Reef, they have rarely been the focus of local scientific study, and the long-term population trend for this species in the region remains unclear. Much of their life history, reproductive biology, population dynamics, and migration patterns are still unknown.

Olive Ridley Turtle Quick Facts

Scientific name: Lepidochelys olivacea Nesting season: September to January Nesting age: 45 years Clutch size: Average 110 Hatching period: November to March Egg and hatchling predators: Crabs, raccoons, pigs, snakes, and birds

Species #6: Leatherback Turtle

The Leatherback Turtle is the largest of all living reptiles in the order Testudines, averaging 1–1.5 m in length, with the heaviest individuals reaching 700 kg, and is critically endangered. Its shell is typically black with white spots and has a soft, leather-like texture, with five longitudinal ridges running along the back.

Leatherback Turtles can be found worldwide, but they primarily nest in tropical regions and are occasionally recorded nesting along Australia's east coast. They feed mainly on fish, shrimp, crabs, and jellyfish. Although they have no teeth, their oesophagus is lined with large, sharp, backward-pointing spines that help break down food before it passes into the stomach and intestines for digestion.

Fewer than 10 Leatherback Turtles nest regularly in Australia. During breeding season, they typically migrate to neighbouring countries, particularly Papua New Guinea and Indonesia.

The long-term population trend for Leatherback Turtles on the Great Barrier Reef is unknown, and related research remains limited. However, given the dramatic decline of Leatherback Turtle populations across the South Pacific, and the likelihood that Great Barrier Reef marine life faces similar threats, marine scientists have been paying increasing attention to this large and remarkable species.

Leatherback Turtle Quick Facts

Scientific name: Dermochelys coriacea Nesting season: December–January Clutch size: Average 90 Hatching period: February–March Hatching success rate: Low Egg and hatchling predators: Crabs and foxes

Summary

That wraps up our introduction to the sea turtle residents of the Great Barrier Reef! All information is sourced from the Great Barrier Reef Marine Park Authority website (www.gbrmpa.gov.au).

If you're still not quite sure how to tell them apart, you can also refer to the identification guide available on the website:

A marine scientist who once worked in Antarctica said that only by going into the ocean yourself — witnessing these creatures and their home firsthand — can you truly understand why we must cherish it all. I think that really is the truth.

Finally, we hope you'll save this article or share it with others, so that more people can open their eyes and join us — to see the ocean, and to protect it.

As Eddie said: