--- title: "Tuatara (Sphenodon punctatus) | AnimalTracks.wiki" description: "The sole survivor of an ancient reptile order: a nocturnal New Zealand islander with a light-sensitive third eye it does not see with, and a sliding jaw that makes a shearing bite." image: "https://animaltracks.wiki/images/animals/tuatara-1.webp" published: "2026-09-06" updated: "2026-09-27" --- # Tuatara (*Sphenodon punctatus*) > **Status**: Checked against 9 sources, listed under Sources below. > **Tagline**: The sole survivor of an ancient reptile order: a nocturnal New Zealand islander with a light-sensitive third eye it does not see with, and a sliding jaw that makes a shearing bite. > **Soundtrack Vibe**: Post-Rock & Cinematic Space // God Is An Astronaut, "All Is Violent, All Is Bright" > **Soundtrack Links**: [Spotify](https://open.spotify.com/track/568nXF19QXYPZnQ6XSkuSH) | [YouTube](https://www.youtube.com/watch?v=ZmWYCIZhBgk) > **Vibe Match**: Slow-burning, patient post-rock for a reptile that keeps growing until it is about 35 years old, one of the slowest growth rates of any reptile. ## Biological Superpowers & Stats - **Taxonomy**: *Sphenodon punctatus* - **Danger Level**: Low - **Conservation Status**: Least Concern ([IUCN Red List](https://doi.org/10.2305/iucn.uk.2019-2.rlts.t131735762a120191347.en)) - **Superpower**: A light-sensitive third eye with a retina and lens, and the lowest optimal body temperature of any reptile, 16 to 21 degrees Celsius. - **Habitat**: Islands off the coast of New Zealand, generally cliff-bound and windswept, usually shared with colonies of breeding seabirds - **Diet**: Mostly beetles, wētā, worms, millipedes and spiders, with the rest made up of lizards, seabird eggs and chicks - **Tags**: reptile, living-fossil, nocturnal, predator, island-life, island-endemic ## Natural History & Behavior On windswept islands off New Zealand lives the **Tuatara** (*Sphenodon punctatus*), the only living member of an entire reptile order, Rhynchocephalia. It looks like a lizard, but it is not one: the tuatara lineage split from the branch that led to every living lizard and snake around 250 million years ago. Adult males are about half a metre long and weigh up to 1.5 kilograms when fully grown, with a crest of spines along the neck and down the back that a male can raise to attract females or when fighting other males. > **Slow Grower, Long Liver** A tuatara keeps growing until it is about 35 years old, and its average life span is about 60 years, though it can live up to 100. In managed care, the San Diego Zoo gives a life span of up to 91 years. ## A Living Fossil? Scientists Disagree Animal Diversity Web puts it bluntly: "The tuatara has been falsely called a living fossil." The label has often been applied because of the tuatara's apparent close resemblance to its Mesozoic forebears. But Rhynchocephalia once held a much greater diversity of forms and was widespread across Gondwana, with its last fossils outside New Zealand dating to about 70 million years ago. One study of the group's fossil skulls concluded the tuatara "is not the product of evolutionary stasis" but the only survivor of a diverse Mesozoic radiation whose decline remains unexplained. A 2017 study that put the label to a formal test came out in its favour: the living tuatara did evolve unusually slowly, and its anatomy sits near the centre of the range of forms seen across all Rhynchocephalia. ## An Eye That Doesn't Actually See On top of the head, a tuatara has a third eye with a retina, lens and nerve endings. It isn't used for seeing. In young tuatara it shows through the skin, but within a few months scales and pigment cover it, making it hard to spot. The eye is sensitive to light and may help the tuatara judge the time of day or the season. ## Two Rows of Teeth, One Shearing Bite A tuatara's upper jaw carries two rows of teeth, and the one row on the lower jaw fits between them when the mouth is closed. After a closing, crushing bite, the lower tooth row slides forward between the upper rows in a propalineal movement, giving a shearing bite that cuts fragments off large prey. Its teeth are fused to the jawbone. Lost or broken teeth are not replaced, and older tuatara have to eat softer food as their teeth wear down. The diet is mostly invertebrates such as beetles, wētā, worms, millipedes and spiders, and the rest is lizards, seabird eggs and chicks. ## Hanging On Offshore In the wild, tuatara now survive on only 32 islands. Rats are considered their most serious threat, and there were probably few, if any, tuatara left on the North and South Islands by the time European settlers arrived. A 2020 genome study put the global population at around 100,000. The Brothers Island tuatara was once treated as a second species, *Sphenodon guntheri*, but that was dropped in 2009 after a genetic study concluded that tuatara is best described as a single species with distinctive geographic variants. ## Frequently Asked Questions ### Is a tuatara a type of lizard? No. Lizards and snakes make up the squamates, and a 2020 study of the tuatara genome dates the tuatara lineage's split from them to about 250 million years ago, early in the Triassic. The tuatara belongs to a separate order, Rhynchocephalia, and is its only living member. *(Source: [Gemmell et al. 2020]())* ### What does the tuatara's third eye actually do? Nobody has pinned it down. Known as the parietal eye, it contains a retina and a lens, but the tuatara does not use it for seeing. It does react to light, which may help the animal tell what time of day or season it is. *(Source: [San Diego Zoo Wildlife Alliance]())* ### How long can a tuatara live? New Zealand's Department of Conservation puts the average at about 60 years, with a maximum of up to 100. Growth is just as unhurried: tuatara have one of the slowest growth rates of any reptile. *(Source: [New Zealand Department of Conservation]())* ### Is "living fossil" the right label for a tuatara? It depends on the definition. The label has been disputed because the tuatara's Mesozoic relatives were widely diverse and because the living tuatara has adaptations of its own. A 2017 study defined a living fossil by a slow rate of lineage evolution and a form near the middle of its group's range, and found the tuatara meets both tests. *(Source: [Herrera-Flores, Stubbs & Benton 2017]())* ## Sources 1. [Tuatara. New Zealand Department of Conservation.]() 2. [Tuatara. San Diego Zoo Wildlife Alliance.]() 3. [Gemmell et al. (2020). The tuatara genome reveals ancient features of amniote evolution. Nature.]() 4. [Sphenodon punctatus. Animal Diversity Web, University of Michigan.]() 5. [Meloro & Jones (2012). Tooth and cranial disparity in the fossil relatives of Sphenodon (Rhynchocephalia) dispute the persistent 'living fossil' label. Journal of Evolutionary Biology.]() 6. [Herrera-Flores, Stubbs & Benton (2017). Macroevolutionary patterns in Rhynchocephalia: is the tuatara (Sphenodon punctatus) a living fossil? Palaeontology.]() 7. [Hay et al. (2009). Genetic diversity and taxonomy: a reassessment of species designation in tuatara (Sphenodon: Reptilia). Conservation Genetics.]() 8. [Gorniak, Rosenberg & Gans (1982). Mastication in the tuatara, Sphenodon punctatus (reptilia: Rhynchocephalia): Structure and activity of the motor system. Journal of Morphology.]() 9. [Hitchmough (2019). Sphenodon punctatus. The IUCN Red List of Threatened Species 2019: e.T131735762A120191347.]() *Published September 6, 2026. 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