Arrau TurtlePodocnemis expansaWhere and when to see them

The arrau turtle, also called the giant South American river turtle, is the largest living member of the side-necked turtle group. It inhabits the Amazon and Orinoco river systems and is closely associated with their seasonal flood cycles. Females are much larger than males and gather at exposed river beaches to lay their eggs. Heavy harvesting of adults and eggs has depleted many populations, while habitat alteration and disturbance add further pressure. Community-based nest protection and regulated conservation programs support recovery in parts of its range.

Size

Adult females commonly reach 60–90 cm in shell length; males are substantially smaller.

Weight

Large adult females can weigh around 50 kg; males are much lighter.

Lifespan

Several decades; longevity in the wild is poorly documented.

Status

Lower Risk/conservation dependent (IUCN, 1996 assessment; outdated).

Arrau turtles are primarily aquatic and spend much of their time swimming, feeding, or resting in the water. Their movements follow changing river levels, with turtles entering flooded habitats during high water and returning toward river channels as water recedes. Females gather near nesting beaches during the low-water season. Nesting can be highly synchronized, with many females using the same sandbank. A female excavates a nest with her hind feet, lays her eggs, and covers them before returning to the river. Hatchlings emerge from the sand and make their way to the water. Researchers have recorded underwater sounds from adults and sounds from hatchlings, suggesting that acoustic communication contributes to their social behaviour.

• It is the largest living side-necked turtle.
• Females grow much larger than males.
• Incubation temperature influences the sex of hatchlings.
• Adults and hatchlings can produce sounds.

Wildlife opportunities depend on the river reach, water levels and species. River-specific viewing months have not been confirmed; general species seasons are not a local sighting forecast.

This species occupies large lowland rivers and connected freshwater habitats in the Amazon and Orinoco basins. In the Amazon, it uses main channels, tributaries, lakes, and seasonally flooded forest. Flooded areas provide access to plant foods during high water. Broad, exposed sandy beaches are essential nesting habitat during falling or low river levels. Suitable habitat depends on connections between feeding waters and nesting sites, as well as a seasonal flood cycle that allows eggs to develop above water.

Arrau turtles eat predominantly plant material, including fruits, seeds, leaves, and aquatic vegetation. Flooded forests offer seasonal feeding opportunities when fruits and other plant matter fall into the water. They also consume some animal material, including invertebrates and carrion, and younger turtles tend to have a more omnivorous diet. By eating fruits and passing some seeds intact, they can contribute to seed dispersal.

Common name

Arrau Turtle

Scientific name

Podocnemis expansa

Animal group

Reptiles

Size

Adult females commonly reach 60–90 cm in shell length; males are substantially smaller.

Weight

Large adult females can weigh around 50 kg; males are much lighter.

Lifespan

Several decades; longevity in the wild is poorly documented.

Status

Lower Risk/conservation dependent (IUCN, 1996 assessment; outdated).

Identification

Adults have a broad, flattened oval shell that is usually gray, olive-brown, or dark brown. The head is relatively small for the body, and the neck folds sideways rather than retracting straight back into the shell. Young turtles show yellowish head markings that become less conspicuous with age. Large females are particularly distinctive, but smaller individuals can be confused with other river turtles, so size alone is not sufficient for identification.