Flatback Sea Turtle

Fascinating facts about the Flatback Sea Turtle

• When a flatback hatchling emerges, its shell measures about 60 mm, roughly the length of a thumb, making it larger than most other sea turtle babies and giving it a better chance to outrun crabs and birds. This size edge shows how early growth can shift survival odds.
• A female flatback may lay three clutches in one season, each spaced about 15 days apart, and each clutch contains roughly 50 eggs that are 55 mm long, about the size of a small grape. Fewer but bigger eggs mean the newborns start life with a stronger head start.
• Flatbacks are typically found in waters of 60 m or less depth and have the smallest range of the sea turtles, unlike other species that migrate long distances.
• The shell of a flatback is unusually thin; a gentle press can crack it, unlike the thicker carapaces of other sea turtles. They nest on warm sands (29-33 °C), which can produce female-biased hatchling ratios.
• Scientists listed the flatback as vulnerable in 1994, but today it is classed as data deficient on the IUCN Red List.

At a glance

About the Flatback Sea Turtle

The flatback sea turtle (Natator depressus) glides along Australia’s shallow continental shelf with a uniquely flattened, lower-dome carapace that feels almost paper-thin under pressure. Its olive-green to grey shell is smooth, non-imbricate, and edged upward along the sides, while the plastron glows a pale yellow. Adults range 76–96 cm (30–38 in) in carapace length and typically weigh 70–90 kg (150–200 lb), though some giants tip the scales at 350 kg (770 lb). Females are larger than males and sport shorter tails, and the species bears a single pair of prefrontal scales and four pairs of costal scutes, features that set it apart from its sea-turtle cousins. In the warm, soft-bottomed bays, lagoons and estuaries of northern Queensland, the Torres Strait, the Gulf of Carpentaria, the Northern Territory and Western Australia, flatbacks remain close to shore, rarely venturing beyond 60 m (200 ft) depth. Their diet is a carnivorous buffet of soft corals, sea cucumbers, shrimp, jellyfish, mollusks and other invertebrates, with occasional bites of seagrass. A striking surprise is the hatchling’s size: at emergence the carapace measures about 60 mm (2.4 in), larger than any other sea-turtle newborn, giving it a head start against predators and a stronger, more efficient swim as it stays near the nesting beaches rather than embarking on a pelagic odyssey.

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