The Great Barrier Reef and the region surrounding Cairns are home to an impressive array of sea life, including six of the world’s seven Sea Turtle species. These include the Green, Hawksbill, Leatherback, Loggerhead, Olive Ridley, and Flatback turtles. Each of these species brings a unique aspect of marine biodiversity to the region, enhancing its global importance and creating opportunities for remarkable wildlife encounters.
Check out the extraordinary video footage below from the World Wild Life Fund Australia (WWF) offering a turtle’s eye view of the Great Barrier Reef.
Green Sea Turtles (Chelonia mydas)
Green sea turtles are the most common sea turtle species found in the Great Barrier Reef. They get their name from the greenish color of their cartilage and fat, not their shells. These turtles can grow up to 1.5 meters in length and weigh over 300 kg.
Green sea turtles are herbivorous, feeding primarily on seagrass and algae. This diet helps maintain the health of seagrass beds, crucial habitats for many other marine species. Green turtles have a unique pattern of movement – they nest on the same beaches where they hatched, with females often migrating over 2,000 kilometers to reach these nesting sites.
The lifespan of green sea turtles is estimated at around 60-70 years. They are currently listed as Endangered on the IUCN Red List due to habitat loss, fishing gear entanglement, illegal trade, and climate change affecting their nesting sites.
Hawksbill Turtles (Eretmochelys imbricata)
Hawksbill turtles are easily recognized by their beak-like mouth and the beautiful pattern of their shells, often used illegally in the tortoiseshell trade. They grow to about 1 meter in length and weigh around 80 kg.
Hawksbills feed predominantly on sponges, aiding in maintaining the balance of coral reef ecosystems. They have a more tropical distribution and nest every two to three years in small clutches.
Hawksbill turtles have a lifespan similar to green sea turtles, living around 50-100 years. They are Critically Endangered, with the primary threats being the illegal trade for their shells, loss of nesting and feeding habitats, entanglement in fishing gear, and marine pollution.
Leatherback Turtles (Dermochelys coriacea)
Leatherback turtles are the largest of all living turtles, reaching lengths up to 2 meters and weighing as much as 900 kg. They are named for their unique leathery shell.
These turtles are unique for their diet – they feed almost exclusively on jellyfish, playing a crucial role in controlling jellyfish populations. Leatherbacks are known for their incredible long-distance migrations between feeding and nesting sites.
Leatherbacks have a shorter lifespan compared to other sea turtles, around 45-50 years. They are listed as Vulnerable, with the major threats being incidental capture in fishing gear, marine pollution, climate change, and egg collection for consumption.
Loggerhead Turtles (Caretta caretta)
Loggerhead turtles get their name from their large heads and strong jaws, used for crushing and eating hard-shelled prey like conches and sea urchins. Loggerheads can grow up to 1 meter in length and weigh approximately 135 kg.
They are mainly carnivorous, with diets significantly influencing the diversity of benthic (sea floor) communities. Loggerheads have a wide global distribution, with nesting beaches spread across several continents.
Loggerhead turtles live around 47-67 years and are classified as Vulnerable. Major threats include loss of nesting habitat, bycatch in fisheries, pollution, and climate change.
Olive Ridley Turtles (Lepidochelys olivacea)
Olive Ridley turtles are the smallest sea turtle species, growing up to 70 cm in length and weighing around 45 kg. They are recognized for their olive-colored carapace.
Olive Ridleys are omnivorous, feeding on a variety of animals and plants, including crabs, shrimp, snails, and algae. They are famous for their mass nesting behavior, known as “arribada,” where thousands of females come ashore simultaneously to lay their eggs.
They have a lifespan of approximately 50 years. They are listed as Vulnerable, with primary threats being egg collection, slaughter for their meat and skin, incidental capture in fishing gear, and loss of nesting habitat.
Flatback Turtles (Natator depressus)
Flatback turtles are named for their flat carapace, distinct from the curved shells of other sea turtles. They grow up to 1 meter in length and weigh around 90 kg.
Flatbacks feed on a variety of invertebrates like sea cucumbers, jellyfish, and prawns. They are unique among sea turtles as their distribution is primarily limited to the northern coast of Australia, with the majority of nesting occurring in Queensland and the Northern Territory.
Flatback turtles are believed to live for over 100 years. They are listed as Data Deficient by the IUCN, indicating that more research is needed to fully understand their population status. Key threats include predation of eggs and hatchlings, marine debris, coastal development, and climate change.
Conclusion
The Great Barrier Reef and Cairns offer a fascinating glimpse into the lives of these ancient marine mariners. Each species is unique and plays a vital role in maintaining the balance of marine ecosystems. Yet, they are under threat from human activities and climate change. As such, it is vital to increase our efforts towards their conservation, ensuring that the region remains a true Turtle Paradise.
Check out these articles
The Great Barrier Reef: A Symphony of Life Under Threat
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