Flatback Sea Turtle (Natator Depressus)

Flatback sea turtle hatchling

Come on in and learn all about the Flatback Sea Turtle. Did you know they can only be found in the marine waters around Papua New Guinea and Australia. They will also nest up to 4 times a year and lay about 50 eggs at a time. That’s quite a bit!

Read on below to learn even more about the Natator Depressus.

Flatback sea turtle facts

  • Scientific Name: Natator Depressus.
  • Size: The average adult size measures to about 3.25 feet or 99 cm. in carapace length.
  • Weight: On average, adults weigh 198 pounds or 90 kg.
  • Habitat: These turtles favour turbid waters inshore. You’ll see them by bays and coastal coral reefs. They prefer grassy shallow areas.
  • Food: The diet consists of jellyfish, sea cucumbers, prawns, molluscs, seaweed, as well as other invertebrates.
  • Australian Environment Protection & Biodiversity Conservation Act. Int’l lists flatback sea turtles as Vulnerable to Extinction. Elsewhere, it is listed as Data Deficient due to a lack of updated research on their state, number, and distribution. On average, they nest four times a year and hatches 50 large eggs each time; that’s the fewest count on any marine animal. The population of nesting females is 20,000 to 21,000

What is the flatback sea turtle?

Flat and smooth shelled, the flatback sea turtle is visible on Australia’s northern beaches as well as the Indonesian archipelago, where it makes the long travel just to feed on the coast of Papua New Guinea. Young flatbacks are grey but develop greenish or olive shaded flippers and pale undersides as they mature.

Some interesting flatback sea turtle facts

  • Flatback sea turtle hatchlings are larger than the hatchlings of other types of sea turtles.
  • It is said that flatback sea turtles are Australia’s very own sea turtles. They nest (and mostly stay) only around Australia.
  • They rank smallest in distribution among all other breeds.
  • Among other types of sea turtles, they are the least studied.
  • In 1988, flatback sea turtles officially became a separate species. Before that, they were considered a variant of green turtles.

Where do flatback sea turtles live?

Little information is available for flatback sea turtles. Within Australia, they mostly reside in the Northern Territory, Western Australia, and Queensland. Shallow waters adjacent to the island are their usual spots for mating or breeding.

 Anatomy

The flatback sea turtle is unique for its flattened shell. Its dome is distinctly lower compared with others. You can see olive green ones with cream undersides. The heads are larger than other sea turtles and feature a more triangular shape. They can be as short as 30 inches in carapace length. Flatbacks have one claw on each flipper.

Habitat

Small in range and non-migratory, much of the habitat of flatback sea turtles are mostly remote. They are drawn to seagrass beds and coastal habitats.

Migration

The geographic range of flatbacks is small and restricted to the tropical areas of Southern Indonesia, Southern Papua New Guinea, and Northern Australia. Unlike other sea turtles, these do not take long or open ocean migrations. They stay in coastal waters, often in waters 200 feet deep or less.

Senses

More studies are needed to gather information on a sea turtle’s sense of taste. As for their hearing, flatbacks and other sea turtles have one single bone in their middle ear. This enables them to perceive vibrations and frequency sounds; this helps with hearing and sensing sounds and objects underwater. They can see well underwater. The flippers and shells are most sensitive to touch. The sense of smell seems acute and helps them to locate food even in murky waters. Some experiments report that hatchlings are quick to recognize and react to a shrimp’s scent.

Experts also talk about an internal compass among sea turtles which helps them orient to earth’s magnetic field. This internal compass guides them as they safely and accurately swim through and navigate the surf zone.

What do flatback sea turtles eat?

Flatback sea turtles are omnivores. You can see them feeding on a variety of prey including bryozoans, jellies, sea cucumbers, shrimps, soft corals, crabs, various fishes, molluscs, and seaweeds.

Movement

Except for their unique looking flat shell, flatback sea turtles act and move the same as other sea turtles.  Land movements may be slow and they sometimes struggle. But water movement is a whole new level. Their expert flippers help them navigate smoothly and quickly through the waters. Even their narrow shells are hydrodynamic, allowing fluidity in water movements.

Laying eggs

Flatback sea turtle eggs incubate for 55 days. A single egg can weigh 77 grams. Flatback sea turtles only breed and nest in Australia. The largest number of nesting females are seen on Crab Island (Carpentaria, Queensland). Most nesting beaches are scattered across Queensland, Western Australia, and the Northern Territory.

Clutch

Flatback sea turtles have smaller clutches (or nests) of eggs. They lay 2 or 3 clutches and each nest are 50 eggs or less. Female flatbacks have a common practice of going back and forth from the shallow waters to the nesting beach to lay eggs. In Queensland, the nesting season happens from October to February. But it could happen all year in the Northern Territory.

What predators does the flat back sea turtle face?

Humans are dangerous predators to flatback sea turtles. Some hunt them for their meat or the eggs. Saltwater crocodiles are the largest reptiles which prey on flatback sea turtles. These crocs tend to attack female flatbacks while nesting. Other predators who devour the nests and the hatchlings are dingoes, Sand Monitor lizards, Pelicans, Night Herons, foxes, and dogs.

Feral pigs, who have great sense of smell, prey heavily on flatback sea turtle eggs. They are a top threat in Cape York Peninsula. Reports state that they consume 90% of eggs laid by flatbacks on some beaches.

Why are flatback sea turtles endangered?

Data and sightings of flatback sea turtles are lacking. The range is limited; they are mostly spotted in Papua New Guinea and around Australia. But they are vulnerable to endangerment because of captivity, fishing, and net entanglement. Other threats to their preservation are diseases, entanglement and ingestion of marine debris and rubbish. The destruction of coral reefs and other feeding habitats also pose problems as well as commercial developments on coastal beaches.

Pollution and increase in coastal developments do pose great threats in many areas. These can cause disorientation in hatchlings, leading them away from safe, familiar zones towards unsafe areas.

Flatback Sea Turtle Documentary

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