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Flatback

Photo by Birgit Braun

Scientific Name

Natator depressus


Flatback sea turtles are named for their very flat shells and are only found in the waters around Australia and Papua New Guinea in the Pacific Ocean. They prefer turbid inshore waters, bays, coastal coral reef and grassy shallows eating a diet of sea cucumbers, jellyfish, mollusks, prawns, bryozoans, other invertebrates and seaweed. Little is known about the mysterious Flatback as they nest in very remote areas up to four times per season, laying an average of 50 eggs at time, which are comparatively quite large. After nesting the eggs incubate for about 55 days, and when the hatchlings emerge, they are larger than most species.

Adults Flatbacks measure up to 3.25 feet in carapace length (99 cm) and weigh an average of 198 pounds (90 kg). Their heads have a single pair of prefrontal scutes (scales in front of its eyes). Their carapace is bony without ridges and has large, non-overlapping, scutes (scales) present with only four lateral scutes. The carapace is oval or round and body is very flat. Flippers have one claw. The edge of their carapace is folded and covered by thin, non-overlapping waxy scutes and has olive-grey with pale brown/yellow tones on margins and the flippers creamy white. The scutes of the hatchlings form a unique dark-grey reticulate pattern, and the center of each scute is olive colored.

The species is particularly vulnerable to threats of capture, harvesting of eggs, destruction of nesting beaches, ocean pollution, oil spills and entanglement in fishing and shrimp nets. Currently the Australia government has Flatbacks listed as Vulnerable under the Australian Environment Protection & Biodiversity Conservation Act. International Flatbacks are listed as Data Deficient by the International Union for Conservation of Nature and Natural Resources. They were previously listed as Vulnerable, however this change in classification does not imply species recovery, it just indicates a lack of recent research into their abundance and distribution.

Where We Live

Seagrass Beds

Seagrasses are flowering plants found in shallow coastal marine waters and are different than seaweed (algae). Algae obtains its nutrients directly from the water through diffusion, while seagrasses use their leaves and roots to obtain nutrients from sediment and water.

Seagrass beds are important feeding and breeding habitats for many marine species, including sea turtles. Unfortunately, seagrass beds have been on the decline since 1940 and more than one-third of the original seagrass around the state has been lost. Along Florida’s Gulf Coast, seagrass beds have declined 8% since 1969. Seagrasses are both an indicator of environmental health and an important breeding ground for the lower tier of the marine food chain.

Seagrass beds are incredibly important habitat for juvenile and adult fish and crabs and shrimp. They also tend to be relatively sensitive indicators of water quality, and in places where humans are affecting water quality, researchers can look at trends over time in seagrass abundance as a way to indicate whether humans are having more or less of an impact on water quality. In addition to pollution, seagrass beds are declining due to being damaged by boat propellers and anchors.

Barrier Islands

Barrier islands are naturally formed by shifting sands that build upon an existing sandbar to eventually form an island. The sand that has accumulated above the water surface becomes the home for the drifting seeds of beach plants. As the seeds grow and develop, their roots stabilize the soil, allowing the development of coastal strand and maritime hammock communities.
Barrier islands support a variety of plant and animal species that are either rare, threatened or endangered.

Barrier islands are greatly affected by the forces of wind and waves and are constantly moving towards or away from the mainland. Because barrier islands provide mainland protection from hurricanes and large storms by absorbing the impact of waves and storm water over flow, entire barrier islands can be severely reshaped or completely destroyed by a major storm.

Lagoons and Estuaries

Estuaries and lagoons are areas where salt water oceans and fresh water rivers mix together, forming brackish water. Lagoons lie between barrier islands and the mainland, while estuaries are found directly on the coast and are open to the near shore area. Because lagoons receive some protection from a barrier island, they have less tidal flow and more standing water, while estuaries have strong tidal flows and little standing water. Lagoons and estuaries support a diversity of plants and wildlife.

Lagoons are an important feeding area for juvenile sea turtles, that mainly feed on the large seagrass beds in the lagoon. Unfortunately, marine pollution has caused the health of the lagoon to deteriorate, and wildlife and plant abundance has decreased.

Beach and Dunes

A beach and dune ecosystem is a dynamic coastal habitat characterized by constantly shifting sands shaped by marine and terrestrial processes. Beaches and dune tend to be nutrient poor habitats where only specialized plants and animals can thrive. It’s home to many species of plants and animals, including shorebirds, sea turtles, invertebrates, and unique vegetation. Dune vegetation includes sea oats (a perennial grass that builds up dunes by trapping sand with its stems) and dune grasses (plants that can tolerate windy, salty conditions with little water). The beach and dune ecosystem is highly sensitive to changes in wave action, wind patterns, and sea level rise.


Vulnerable

Details

  • Size

    3 feet

    Adults measure up to 3.25 feet in carapace length (99 cm)
  • Weight

    198 lbs

    Adults weigh an average of 198 pounds (90 kg)
  • Range

    Limited

    Range is very limited and it is found only in the waters around Australia and Papua New Guinea in the Pacific.
  • Population

    21 k

    Population estimate is between 20,000 and 21,000 nesting females

What We Eat

Jellyfish
Bryozoans
Sea Cucumbers
Mollusks

Threats