Tuatara
Not a lizard — the last survivor of an entire reptile order that was widespread before the dinosaurs
Photo via Wikimedia Commons
Superpower
The tuatara has a functional third eye on the top of its head — complete with a lens, retina, and a direct nerve connection to the brain. It's visible in hatchlings and gradually covered by scales in adults. Its purpose is unclear, but it's sensitive to light and likely regulates seasonal behavior and circadian rhythms. The tuatara also has a unique double-row tooth arrangement: the lower jaw fits between two upper rows in a shearing action found in no other living animal.
Overview
Tuatara (Sphenodon punctatus) are the sole surviving species of order Rhynchocephalia — a lineage that was widespread in the Mesozoic Era before mysteriously declining while other reptile groups flourished. By the time humans arrived in New Zealand, they survived only on offshore islands, protected from introduced rats and predators by open water. They're not lizards, geckos, or iguanas — they're the last representative of an entire reptile order that diverged from all other scaled reptiles over 240 million years ago, predating the first dinosaurs.
Found in
Offshore islands of New Zealand, where they naturally survived after extinction on the mainland from introduced predators. Now subject to intensive conservation and mainland reintroduction programs in predator-free sanctuaries.
Things worth knowing
- 1
Tuatara have the slowest metabolism of any reptile — their body temperature works optimally at 12°C, and they can remain functional at 5°C, temperatures at which other reptiles become completely immobile. They breathe only once per hour at rest.
- 2
Female tuatara reproduce only once every 4 years. Their eggs take 11–16 months to hatch — the longest incubation period of any reptile. Despite this, individuals live over 100 years and females reproduce into their 80s.
- 3
Tuatara have no external ears. They detect sound through bone conduction — vibrations travel through the skull to the inner ear — giving them sensitivity to low-frequency ground vibrations but not to airborne sound in the way most vertebrates hear.
- 4
The tuatara's vertebrae are biconcave — hollowed on both sides, the same design as fish vertebrae — a structure that was replaced by more complex forms in all other reptile lineages hundreds of millions of years ago. It's a genuine fossil feature retained in a living animal.
- 5
Rising temperatures are skewing tuatara sex ratios toward males, because nest temperature determines sex. Unless the trend reverses, some populations face reproductive collapse within decades — not from hunting, but from climate change affecting an animal that has survived every major extinction event for 240 million years.