New Zealand


Islands, scrubland

Living fossils

Not too many creatures can claim to be “one of a kind,” but that’s a boast the tuatara can make. In fact, the tuatara is one of the most unique animals in the world. Although it looks like a lizard, it really is quite different. Found in New Zealand only, the tuatara’s closest relatives are an extinct group of reptiles around at the time of the dinosaurs. This is why some scientists refer to tuataras as “living fossils.”

What makes them so different?

Both male and female tuataras have a crest of spiky scales, called spines, down the center of their back and tail. Males are larger than the females. The name “tuatara” is a native Maori word meaning “peaks on back” or “spiny back.” Tuataras have no external ears as lizards do; they enjoy cooler weather, while lizards like it warm; and, unlike lizards, tuataras are nocturnal.

But their most curious body part is a “third eye” on the top of the head. The “eye” has a retina, lens, and nerve endings, yet it is not used for seeing. It is visible under young tuataras’ skin but becomes covered with scales and pigment in a few months, making it hard to see. The unique eye is sensitive to light and may help the tuatara judge the time of day or season.

When tuatara eggs get too cold, their development stops until it gets warmer again. That’s why they take so long to hatch.
Like some lizards, a tuatara can regrow a lost tail.
A female tuatara’s spines aren’t as big as a male’s. A male can fan out his spines to attract a female.
The color of tuataras ranges from olive green to brown to orange-red, and they can change color over their lifetime.
Tuataras shed their skin once a year.
Tuataras have the lowest metabolism of any reptile.
Most reptile species have the ability to replace lost or worn teeth, but tuataras do not.

In 1995, the San Diego Zoo was honored to be the first institution outside of New Zealand to receive Brothers Island tuataras on breeding loan, with the approval of the Te Ati Awa, a Maori native group. Its chieftain, in full costume, presented 10 tuataras during a special ceremony at the Zoo. The animals were three years old at the time—just youngsters—having hatched in 1992. So important was the tuataras’ arrival that Air New Zealand airlines allowed Zoo officials to hand-carry the animals in the passenger section during the long flight from New Zealand to their new home in San Diego. It was the first time the airline waived its “no animals on board” rule!

Today the young tuataras continue to thrive in an off-exhibit area of the Zoo. They are now coming into breeding age, and their keepers have seen some ovary development. But egg development can occur and resorb, so we are still patiently waiting for the pitter-patter of tiny tuataras. The group is routinely measured, weighed, and given medical exams, which include sonograms for the females.

Tuataras in trouble
Tuataras used to inhabit the two major islands in New Zealand and numbered in the millions. Then, the first humans arrived from Polynesia, bringing rats and dogs that ate tuatara eggs and youngsters. When Europeans arrived in New Zealand, they also brought more dogs and rats, as well as cats and ferrets. These introduced animals wiped out most tuatara populations. The threat to tuataras was so serious that in 1895, the New Zealand government fully protected tuataras and their eggs.

Even with this protection, tuatara populations continued to disappear as rats reached one island after another. The most recent extinction of an island population happened in 1984, when rats killed all the tuataras on a 25-acre (10-hectare) island in just 6 months. Recent studies have confirmed that tuatara populations on islands without rats are much larger than populations on islands with rats. Today, tuataras survive on just 37 tiny offshore and mainland islands in New Zealand.

From dark days to a brighter future
The New Zealand Department of Conservation launched a recovery program for tuataras in 1988. The program aims to stop the continuing extinction and help tuataras threatened by rats. Hatchlings are raised by biologists until large enough to survive in the wild, a process called “headstarting.” They are then released onto rat-free islands.

This new hope for tuataras is good news for other species, too. Restoring natural habitat for tuataras also helps kiwis, several seabirds and lizards, and a large flightless insect called the giant weta. These animals had also been harmed by the rats and other introduced predators.

The San Diego Zoo is one of two zoos selected to hold a satellite colony of the Brothers Island tuatara. They are currently in an off-exhibit area. Our researchers accessioned living fibroblast cells from a female Brothers Island tuatara into our Frozen Zoo®. The Frozen Zoo contains banked cells from genetically valuable individuals and may offer a means to conserve genetic diversity in captive populations. The tuatara's cells took nearly four months to grow to sufficient numbers to freeze (most species require only four weeks) but are now preserved in the Frozen Zoo.

With these programs in place, tuataras and other animals native to New Zealand have a brighter future ahead.