Dive with me in the world of this unique “living fossil” from New Zealand and the only representative of the order of “beak heads” – the tuatara Sphenodon punctatus.
When the Gondwana supercontinent split apart 180 million years ago, these lonely survivors were isolated on islands that would one day become New Zealand, which probably protected them from much competition until humans showed up around 700 years ago.
That’s, of course, when things got worse for them, as they do when humans are involved. You see, the first humans that arrived from Polynesia brought rats and dogs that ate tuatara eggs and youngsters.
The introduction by the Maori of the Polynesian rat into New Zealand resulted in the eradication of several terrestrial and small seabirds. Let’s move on to specifics like size, diet, habitat, etc., to see why tuataras are so fascinating.
Table of Contents
1. How To Pronounce Tuatara?
Tuatara’s name derives from the Māori language, and means “peaks on the back” or “spiny back” and is pronounced as [too-uh-tahr-uh] or [too-uh-tair-uh].
2. What are the Tuatara Species?
The single species of tuatara is the sole surviving member of the order Rhynchocephalia (“beak-heads”), an order of lizard-like reptiles, which originated in the Triassic period around 240 million years ago.
While there is currently only one living species of tuatara, two species were previously identified: Sphenodon punctatus (“spotted”), or northern tuatara, and the much rarer Sphenodon guntheri, or Brothers Island tuatara.
The Brothers Island tuatara has olive-brown skin with yellowish patches, while the color of the northern tuatara ranges from olive green through grey to dark pink or brick red, often mottled, but always with white spots.
In 2009, it was concluded they only represent geographic variants, and only one species should be recognized, sorry brothers.
3. Where do Tuataras live?
Tuataras live on 37 small, relatively inaccessible islands off the coast of New Zealand, the North Island, and the Brothers Island and are endemic to New Zealand. They were once thriving but became extinct on the mainland before the arrival of European settlers.
The islands, which are a tough nut to crack for any animal, are generally cliff-bound, frequently exposed to strong winds, and support a natural, often stunted, vegetation of salt and wind tolerant species.
This habitat is cold and damp, with temperatures rarely exceeding 70°F (21°C) and a humidity level of about 80 percent. They support several species of sea birds, whose nutrient-rich guano helps, in return, to keep the island’s ecosystem.
4. How big do Tuataras get?
Adult tuatara males are bigger than females and measure 61 cm (24 in) in length, and females measure 45 cm (18 in). Males weigh up to 1 kg (2.2 lb), and females up to 0.5 kg (1.1 lb) and Brother’s Island tuatara weigh up to 660 g (1.3 lb). In captivity, they can grow up to 30% bigger.
5. How long do Tuataras live?
Let me blow your mind here, as some experts believe that captive tuatara could live as long as 200 years!
The average lifespan of tuatara is 60 years, though, with known specimens living more than a hundred years old. Henry, the tuatara, recently became a father at the age of 111, after a romantic affair with an 80-year-old female named Mildred in Southland Museum and Art Gallery.
Henry underwent an operation to remove his tumor at the age of 105. He was often kept in solitary confinement due to his foul temper, but after his successful operation, he was held in the company of three female tuataras.
Part of the reason for their longevity may be their slow metabolism as tuataras can tolerate much lower temperatures than most reptiles and the fact that they hibernate during the winter.
6. How do Tuatataras live and behave?
Tuatara is frequently referred to as living fossils and has been protected by law since 1895. Like many of New Zealand’s native animals, they are threatened by habitat loss and introduced predators.
Tuataras were extinct on the mainland, with the remaining populations confined to 32 offshore islands until the first North Island release in 2005.
Although they will often bask in the sun to warm their bodies, adult tuataras are terrestrial and nocturnal reptiles. At the same time, hatchlings are active during daytime (diurnal) and hide under logs and stones, likely because adults are cannibalistic.
Yikes, you know it’s bad when you have to hide from your parents and live in opposite shifts.
Tuataras hibernate during winter, and they thrive in temperatures much lower than those tolerated by most reptiles. They have the lowest body temperature of any reptile as their optimal body temperature is from 16 to 21 °C (61 to 70 °F).
The tuataras, which share their island habitat with burrowing seabirds during nesting season, use the birds’ burrows for shelter when available or dig their own. Very opportunistic, if I can say so.
7. What does Tuatara eat?
Due to its low metabolic rate, the tuatara eats much less frequently than other reptiles. Still, they have a rather diverse diet consisting of arthropods, earthworms, snails, bird eggs, small birds, frogs, and lizards, and a native cricket-like insect the size of a mouse called weta.
Young tuataras are also in danger of being eaten by adults, and that’s why they usually hunt for
8. What is unique about eyes of the Tuatara?
The tuatara has eyes that can focus independently on three types of photoreceptive cells, all with fine structural characteristics of retinal cone cells used for day and night vision.
The eyes also have a retro-reflector lying immediately behind the retinas. It is a feature that many vertebrates have that helps with seeing in the dark and is called tapetum lucidum.
9. Does Tuatara have a third eye?
Tuataras have a third eye, the so-called parietal eye, that is only visible in hatchlings because it gets covered in scales and pigments after four to six months of tuatara’s life.
It is located on the top of its head, and it’s compounded by the retina, lens, cornea, and nerve endings, but it is not used for vision. It is a photosensory organ connected to the pineal body, active in triggering hormone production (including reproduction) and thermoregulation.
It is sensitive to changes in light and dark; it does not form images, having only a rudimentary retina and lens.
Though it’s still a subject of ongoing research, it is believed to be useful in absorbing ultraviolet rays and in setting circadian and seasonal cycles.
10. How old is the oldest tuatara?
As much as I could find, the oldest known tuatara is called Henry and is located in The Southland Museum, which cares for over 100 tuataras, all at different stages of development, from newborn babies to teenagers.
The world-famous Henry is over 110 years old, and incidentally, Henry holds the world record for living in captivity for over 46 years. He made the headlines recently for mating successfully with an 80-year old Mildred.
11. Do Tuataras have predators?
Tuataras used to inhabit the two major islands in New Zealand and numbered in the millions. Still, they are in real danger mainly because when the first humans arrived from Polynesia, they brought rats and dogs that ate tuatara eggs and youngsters.
Later, when Europeans arrived in New Zealand, they also brought more dogs and rats, as well as cats and ferrets. As early as 1895, the New Zealand government had to protect tuataras and their eggs, bringing new laws to protect them.
Even with this protection, tuatara populations continued to disappear as rats reached one island after another, and in 1984 rats killed all tuataras on a 25-acre (10-hectare) island in just six months.
Today, tuataras survive on just 37 tiny offshore and mainland islands in New Zealand.
12. How do Tuataras reproduce?
Tuatara mate in midsummer and females mate and lay eggs only once every four years. The males put up a show during courtship, making his skin darker, raising his crests, and parading toward the female.
He also slowly walks in circles around the female with stiffened legs, and she will either submit and allow the male to mount her or retreat to her burrow.
Tuatara sex is sometimes referred to as a “cloacal kiss” since males do not have a penis but rudimentary hemipenes. They reproduce by the male lifting the tail of the female and placing his vent over hers, and intromittent organs are used to deliver sperm to the female during copulation.
Along with birds, the tuatara is one of the only members of amniota to have lost the ancestral penis.
They reproduce very slowly, taking 10 to 20 years to reach sexual maturity, but wild tuatara is known to be still reproducing at about 60 years of age and captive at even more than 100 years old.
13. What is special about Tuatara’s babies?
The sex of a hatchling depends on the temperature of the egg, with warmer eggs tending to produce male tuatara and cooler eggs producing females. Eggs incubated at 21 °C (70 °F) have an equal chance of being male or female.
However, at 22 °C (72 °F), 80% are likely to be males, and at 20 °C (68 °F), 80% are likely to be females; at 18 °C (64 °F) all hatchlings will be females.
Some evidence indicates sex determination in tuatara is determined by both genetic and environmental factors.
14. Are Tuatara Dinosaurs?
They are the only surviving members of a distinct reptilian order Sphehodontia that lived alongside early dinosaurs and separated from other reptiles 200 million years ago in the Upper Triassic period.
It means that tuataras are not dinosaurs nor lizards but just a super old species.
15. Are Tuataras Endangered?
Unfortunately, tuataras are endangered so much so that in 1895, the country of New Zealand awarded the tuatara strict legal protection.
It is currently considered a CITES (Convention on the International Trade in Endangered Species) Appendix I species which is the most restricted classification for a species making it hard for even zoos to possess them, and the public display of tuataras has only recently been allowed.
A great effort has been made in eradicating the Polynesian rat that inhabits many of the islands where tuataras are located to give tuataras a fighting chance at survival.
For example, tuataras were removed from Stanley, Red Mercury, and Cuvier Islands in 1990 and 1991 and maintained in captivity to allow Polynesian rats to be eradicated on those islands.
All three populations were bred in captivity, and after successful eradication of the rats, all individuals, including the new juveniles, were returned to their islands of origin.