Natator depressus (Flatback Sea Turtle)

Natator depressus, commonly known as the Flatback Sea Turtle, is a unique species found primarily in Australian waters. It is distinguished by its relatively flat shell and is one of the least migratory sea turtles, staying close to its coastal habitats.

Scientific Classification

Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Family: Cheloniidae
Genus: Natator
Species: Natator depressus

Common Names

Flatback Sea Turtle
Australian Flatback Turtle

Identification

Description

The Flatback Sea Turtle has a smooth, flattened carapace with a pale olive-gray coloration. The plastron is cream or yellowish. Unlike other sea turtles, its shell is relatively soft with upturned edges. Adults typically measure 76–96 cm in carapace length and weigh between 70–90 kg.

Sexual Dimorphism

Males have longer tails and a more curved plastron compared to females. Their claws are also longer, aiding in mating. Females tend to have wider, rounder shells.

Native Origin and Distribution

Geographical Range

This species is native to the coastal waters of northern Australia, with occasional sightings in Papua New Guinea and Indonesia. Unlike other sea turtles, Flatbacks do not venture far into the open ocean.

Preferred Habitat

Flatbacks prefer shallow, soft-bottomed coastal waters, including bays, lagoons, estuaries, and seagrass meadows. They are rarely found in deep ocean waters and are more commonly seen in turbid environments.

Behavior

Feeding Habits

Flatbacks are opportunistic feeders, consuming soft-bodied prey such as jellyfish, sea cucumbers, soft corals, shrimp, and mollusks. They also feed on seagrass and algae occasionally.

Predators

While hatchlings face high predation from birds, crabs, and fish, adult Flatbacks have fewer natural predators due to their size. However, sharks and saltwater crocodiles are known to prey on them.

Reproduction

Breeding Season

Flatbacks nest year-round but peak nesting occurs between October and January.

Reproductive Method

Females lay around 50 eggs per clutch, which is fewer than most other sea turtle species. The eggs are larger and have a relatively high hatchling survival rate. Nesting occurs on Australian beaches, particularly in Queensland and Northern Territory.

Conservation

Extinction Status

Flatback Sea Turtles are classified as Data Deficient by the IUCN due to a lack of comprehensive population studies.

Threats

Threats include habitat destruction, egg predation by feral animals, entanglement in fishing gear, and coastal development. Pollution and climate change also pose risks by affecting nesting beaches and food availability.

Conservation Measures

Protected nesting sites, restrictions on coastal development, and fishing regulations help conserve Flatbacks. Turtle exclusion devices (TEDs) are required in trawl fisheries to reduce accidental bycatch.

Economic Importance

Flatbacks contribute to marine biodiversity and play a role in maintaining healthy seagrass and jellyfish populations. Ecotourism activities, such as turtle-watching tours, also generate revenue in Australia.

Interesting Facts

Flatback hatchlings are larger than those of other sea turtles, giving them a better chance of survival. Unlike most sea turtles that undertake long migrations, Flatbacks stay within Australian waters throughout their lives. Their soft carapace makes them more vulnerable to injuries compared to other sea turtles with harder shells.