You’ve probably seen a picture of a tuatara and thought, "Cool lizard." Most people do. Honestly, if you saw one scurrying across a rock in New Zealand, you’d have no reason to think otherwise. It has the scales, the tail, the clawed feet, and that classic reptilian stare that seems to peer right through your soul. But here’s the thing: calling a tuatara a lizard is like calling a human a marsupial. It’s fundamentally wrong.
These creatures are the last survivors of Sphenodontia, an entire order of reptiles that thrived alongside the earliest dinosaurs about 250 million years ago. While the rest of their relatives died out roughly 60 million years ago, the tuatara just... kept going. They are living fossils in the truest sense, though biologists like Dr. Nicola Mitchell and others who study them often prefer the term "relic species" because they have actually evolved quite a bit under the hood. They aren't frozen in time; they're just the only ones left at the party.
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The Third Eye and Other Weirdness
If you look at the top of a tuatara hatchling's head, you’ll see something straight out of a sci-fi novel. It’s a parietal eye. A literal third eye. It has a lens, a retina, and nervous connections to the brain, though it gets covered by scales as the animal matures.
Why?
Scientists aren't 100% sure. We know it helps with thermoregulation and probably sets their circadian rhythms by sensing light levels. It's a vestigial trait that many ancient vertebrates had, but while most species lost it or shrunk it down to almost nothing, the tuatara kept a version that is surprisingly complex.
Their teeth are another biological glitch. Most reptiles have teeth that sit in sockets or are glued to the side of the jawbone. Tuatara teeth are actually just serrated projections of the jawbone itself. They have two rows of teeth on the upper jaw and one row on the bottom. When they bite, the bottom row fits perfectly between the two top rows. This creates a shearing effect so powerful they can saw through the hard chitin of large insects or even the bones of small seabirds. But there’s a catch. Since these aren't "real" teeth, they don't get replaced. An old tuatara eventually wears its teeth down to smooth bone nubs and has to switch to a diet of soft worms or larvae. It's a rough way to age.
Life in the Slow Lane
Everything about the tuatara happens at a glacial pace. They live for well over 100 years. There’s a famous male named Henry at the Southland Museum and Art Gallery in New Zealand who became a father for the first time at the ripe old age of 111. Imagine that. He spent decades being cranky and solitary until a female named Mildred caught his eye, proving that it’s never too late for a mid-life (or late-life) crisis.
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Their metabolism is incredibly low. They thrive in temperatures that would put a typical lizard into a coma. While most reptiles need heat to move, tuatara are perfectly happy at $10^{\circ}C$ ($50^{\circ}F$). They breathe slowly—sometimes only once an hour during sleep. They grow slowly. They reach sexual maturity at about 15 to 20 years.
This slow-motion lifestyle is a double-edged sword. It’s great for surviving on islands with limited food, but it makes them incredibly vulnerable to change. If a population gets hit by a predator or a habitat shift, they can't just "bounce back." Their reproductive cycle is too sluggish. A female only lays eggs every two to five years, and those eggs take up to 15 months to hatch. That is one of the longest incubation periods of any reptile on Earth.
The Climate Change Trap
Climate change isn't just a vague threat for these guys; it's a literal gender crisis. Tuatara have temperature-dependent sex determination (TSD). The temperature of the soil during the middle of the incubation period decides whether the babies are boys or girls.
In the tuatara's case, warmer soil produces males. Cooler soil produces females.
A study led by Dr. Nicola Mitchell found that even a rise of one or two degrees in average soil temperature could result in entire generations of only males. If there are no females being born, the species hits a dead end. We’re already seeing this happen in certain North Island populations. Conservationists are literally having to consider moving tuatara further south to cooler islands or providing artificial shade over nesting sites to keep the daughters coming. It’s a hands-on race against the thermometer.
Survival on the Offshore Islands
You won't find tuatara on the New Zealand mainland anymore, at least not in the wild. When humans arrived, they brought rats, cats, and dogs. For a slow-moving creature that leaves its eggs in the ground for over a year, rats are basically a death sentence. The rats don't just eat the babies; they eat the eggs.
By the late 1800s, tuatara were wiped out everywhere except for about 32 offshore islands. These islands are rugged, wind-swept, and often shared with thousands of seabirds like petrels and shearwaters.
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It's a weird roommates-with-benefits situation.
The birds dig burrows, and the tuatara move in. The birds provide "room service" in the form of dropped fish, spilled scraps, and their own guano, which attracts the beetles and crickets that tuatara love to eat. Sometimes, the tuatara repays the favor by eating a stray chick. It’s a tense living arrangement, but it works. Without these seabird colonies, the tuatara probably wouldn't have survived the last few centuries.
The Genome Revelations
In 2020, a massive international team of researchers sequenced the tuatara genome. It was a huge deal. What they found was a mess—in a good way. The tuatara genome is about 50% larger than the human genome. It contains a strange mix of mammalian and reptilian sequences.
They found genes related to smell, vision, and temperature regulation that are totally unique. It turns out the tuatara has the fastest molecular evolution rate of any vertebrate studied, even though its physical appearance hasn't changed much. Its DNA is sprinting while its body is strolling. This research, published in Nature, basically proved that "living fossil" is a bit of a misnomer. They are highly specialized survivors that have fine-tuned their biology to thrive in a very specific, cool-temperate niche.
Misconceptions You Should Stop Believing
- They are dinosaurs. Nope. They lived at the same time, but they are a different branch of the tree.
- They are lizards. Again, no. They belong to Rhynchocephalia. Lizards and snakes belong to Squamata. They split apart roughly 250 million years ago.
- They are "primitive." This is a bit insulting to a creature that has survived multiple mass extinctions. Their biology is complex and highly adapted.
- They are easy to find. Unless you are on a strictly regulated sanctuary island or at a high-end zoo like Zealandia in Wellington, you aren't going to stumble across one.
Protecting the Future of the Tuatara
The Māori people consider the tuatara to be kaitiaki (guardians) of knowledge. This cultural connection is a big reason why conservation efforts in New Zealand are so intense. Groups like the Ngāti Koata iwi work closely with the Department of Conservation (DOC) to manage the populations.
This isn't just about "saving a cool lizard-thing." It's about preserving an entire branch of life. If the tuatara goes extinct, we don't just lose a species; we lose an entire order of animals. It would be like if every single mammal on Earth died out, leaving only one weird species of shrew behind—and then that shrew died too.
Actionable Steps for the Curious
If you're fascinated by these ancient survivors and want to see them or help them, here is how you can actually engage:
- Visit Zealandia Te Māra a Tane: Located in Wellington, this is a fenced eco-sanctuary where tuatara live in a wild-state environment. It’s your best shot at seeing one in its natural habitat without a special permit.
- Support Rat-Free Initiatives: The biggest threat to NZ biodiversity is invasive predators. Supporting "Predator Free 2050" initiatives helps create the mainland habitats where tuatara could eventually return.
- Check out the Southland Museum: If you're in Invercargill, visit Henry. He’s a legitimate celebrity and a testament to how long these animals can thrive with the right care.
- Educate on the "Third Eye": Spread the word that they aren't lizards. The more people understand their unique place in the evolutionary tree, the more political and social will there is to fund their protection.
- Follow the Tipping Point: Keep an eye on climate research regarding TSD (Temperature-dependent Sex Determination). Supporting organizations that focus on climate resilience in island habitats is crucial for the tuatara’s long-term survival.
The tuatara is a reminder that the world doesn't always belong to the fast or the most adaptable to heat. Sometimes, the winner is the one who can sit still, breathe once an hour, and outlast everyone else by sheer, stubborn persistence.