Why these ancient Australian turtles tuck their heads sideways instead of pulling them back

Nature · Published 3 October 2026 Swipe more like this →

In short: Snake-necked turtles are masters of the side-tuck, a unique defensive maneuver that sets them apart from their peers. Rather than retracting their heads directly into their shells, these ancient reptiles fold their long necks horizontally. This distinct behavior is a hallmark of the Chelodina genus, a diverse group found across Australia.

The Chelodina genus, commonly known as snake-necked turtles, represents an ancient lineage within the family Chelidae. These reptiles are classified as side-necked turtles, or Pleurodira, a term describing their peculiar method of protection. When threatened, they do not pull their heads straight back; instead, they tuck them partially around the side of their bodies. This evolutionary adaptation is found in species native to Australia, New Guinea, East Timor, and the Indonesian Rote Island.

Taxonomy within this group has a complex history, marked by shifting classifications and evolving nomenclature. Current understanding, largely following work by Georges and Thomson, divides the genus into subgenera such as Chelodina, Chelydera, and the monotypic Macrochelodina. The subgenus Chelydera, described in 2020, consists of thick-necked species that act as specialized fish eaters, employing a strike and gape feeding strategy. These turtles can reach significant sizes, with Chelodina (Chelydera) expansa growing to shell lengths of approximately 45 cm.

The fossil record provides a window into the deep history of these creatures. Researchers have identified extinct species like Chelodina alanrixi, which dates back to the Eocene period and was discovered in Queensland. Other extinct members, such as Chelodina insculpta, have been dated to the Pliocene and Pleistocene epochs. These findings highlight the long-standing presence of the genus in the Australian landscape, where they have persisted through vast geological timeframes, adapting their unique anatomy to survive in a wide variety of water bodies.

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