Overview
The Tuatara (Sphenodon punctatus) is an extraordinary reptilian survivor that holds a revered position in evolutionary paleontology. Although resembling a robust lizard, it is not a lizard at all; rather, it is the sole surviving member of Rhynchocephalia, an ancient reptilian order that flourished alongside the early dinosaurs over 200 million years ago. Endemic exclusively to New Zealand, this living fossil possesses an extraordinary suite of primitive anatomical traits that have vanished from all other living reptiles.
Biology and Physical Characteristics
Featuring a mottled greenish-brown scaly hide and a pronounced crest of spiny scales running down the center of its spine (its Māori name translates to ‘peaks on the back’), the tuatara possesses unique skeletal traits. It has two parallel rows of upper teeth with a single lower row that fits precisely between them when biting, creating a shearing saw-like bite that slices through chitinous insect armor. Remarkably, hatchlings possess a fully developed ‘third eye’ (parietal eye) atop their head, complete with a primitive lens, retina, and nerve connection to the brain, which helps regulate circadian and hormonal cycles before being covered by opaque scales.
Behavior and Ecology
Tuatara are nocturnal and uniquely adapted to cold temperatures, remaining active at ambient temperatures as low as 5°C (41°F)—temperatures that would leave modern lizards completely paralyzed. They exhibit an astonishingly slow metabolic rate, breathing only once per minute while resting. In their island strongholds, they maintain an intricate ecological commensalism with burrowing shearwaters and petrels, sharing subterranean burrows with the seabirds during daytime hours and foraging at night on beetles, snails, and giant flightless wētā.
Conservation and Human Impact
Wiped out entirely from the New Zealand mainland following Polynesian and European settlement due to the introduction of Pacific rats (kiore) and brown rats, tuatara survived only on roughly 35 offshore, rat-free predator sanctuaries. Decades of aggressive island conservation, aerial rodent eradications, and successful captive breeding programs have allowed populations to climb past 100,000 individuals, leading to recent historic reintroductions into mainland fenced ecological ecosanctuaries like Zealandia in Wellington.
Interesting Factoid
Tuatara take an astonishing 10 to 20 years to reach sexual maturity and can continue reproducing past 100 years of age; in 2009, a captive male named Henry became a first-time father at the estimated age of 111.
Last updated: October 2026