The tuatara is an ancient reptile which evolved over 200 million years ago and lived alongside the dinosaurs managing to outlive them.
While they may superficially resemble a lizard they are the only living members of their order, Rhynchocephalia. Their teeth are not separate structures and instead are serrations in the skull. Males are larger than females.
These carnivorous animals primarily feed on insects, birds and their eggs and frogs. They have been recorded to prey upon their own young.
Tuatara have one of the slowest reproductive cycles of any reptiles. They do not first breed until 20 years of age. Once they reach this age they will only produce eggs once every four years.
Read on to learn more about these remarkable reptiles.
Spiky scales run down the back of the tuatara and along their tail. This is larger in males than in females. The crest is made up of triangular folds of skin. When displaying it they can flatten it out.
They have scaly skin which is colored green or brown in color this may change over the course of their life as they shed their skin at least once each year.
Their upper jaw is shaped like a beak. They have one bottom row of teeth and two on the top.
Tuataras differ from lizards in that their teeth are not separate structures instead being serrations along the upper and lower jaw. They also have two openings in the skull whereas other lizards have one.
On top of the head tuataras have what is known as a third eye or ‘parietal eye.’ This is able to see when they hatch but by 6 months old opaque scales cover it. Scientists are still yet to work out the purpose of this eye. One theory suggests that it helps to absorb ultraviolet rays which they use to manufacture DNA.
Each foot is equipped with sharp claws which will allow them to burrow in to the ground. The legs are strong to assist with this.
Tuatara reach up to 80cm (31.5in) long and weigh up to 1.3kg (2.9lbs). Females are smaller than males.
Tuataras are carnivorous animals. They feed upon insects, lizards, birds, bird eggs and frogs. Adult tuataras have also been known to feed upon young ones.
As they grow the tuataras teeth begin to wear down. Over time they need to take to feeding upon softer foods which they can chew between their gums as the teeth wear down.
Their metabolism is incredibly slow and they have been recorded to breathe once every seven seconds on average with some holding their breath for over an hour.
New Zealand is the only place in the world where the tuatara can be found. Previously they lived across much of the mainland but they were driven to extinction after humans arrived.
Currently they are restricted to a number of offshore islands. Some of these are naturally surviving individuals while others are the result of releases from other populations or captive breeding efforts.
Tuatara make their home in forest and shrubland habitats.
They will live in an underground burrow including those dug by seabirds.
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Males will find a females burrow around March and begin sitting outside hoping she will emerge and they can mate. They puff out the spines around the neck to impress her. Males may breed every year but females generally only reproduce every two to five years.
Once the female is ready to mate the pair will rub their cloacas together as males have no reproductive organ. The eggs do not automatically begin forming as females can store sperm for up to 12 months.
After this 1 to 19 white, leathery eggs with a soft shell is laid in their burrow. After 12 to 15 months of incubation the eggs hatch. This is the longest incubation period of any reptile. It is this long period which allows rats the opportunity to eat many of the eggs which has led to their numbers decreasing. Part of the reason the eggs incubate for so long is that development stops if the egg becomes too cold.
What gender the hatchlings are depends on what temperature they are incubated at. A change of 1oC (1.8oF) is enough to change males to females. Scientists believe that climate change could lead to the decline of tuataras as there will be more males in the population.
Following hatching these young tuatara are on their own with the mother not staying around to protect them.
Sexual maturity is reached between 10 and 20 years old when they will begin to produce their own young. Females will breed once every four years on average.
Tuataras are nocturnal reptiles. On occasion though they will warm their bodies by sitting in the sun. Young tuatara will be most active during the day and hide under logs and stones at night so they can avoid the cannibalistic adults. Over winter tuataras will undertake a period of lowered activity.
Unlike other reptiles they are highly tolerant of the cold and will remain active at temperatures as low at 10oC (50oF).
On most occasions tuataras dig their own burrow. During the breeding season of burrowing seabirds like petrels, shearwaters and prions they may use the nest of these birds.
Predators and Threats
They will fiercely defend their territory. They have a bite that they use on predators which can inflict severe damage.
The only predators of the tuatara are those which have been introduced including stouts, dogs, foxes, cats and rats. Rats are believed to have had one of the largest roles in their decline. As rats have been removed from the islands where they live they have seen population increases.
If they lose their tail they are able to regrow this.
Habitat loss is another threat to the future of the tuatara.
These animals are highly sought after in the pet trade and smuggling has been attempted in the past. To date no known exports have been successful.
At present the population is believed to be made up of 55,000 mature individuals.
On some islands the population of tuatara is so small that they have low genetic diversity as the populations are isolated from one another.
A tuatara known as Henry bred at 100 years old in 2009. He needed to have a cancerous tumor removed before he could breed.
Up until 2006, when it was phased out, New Zealand’s five-cent coin featured a tuatara on one side.
Tuataras are the only surviving members of the order Rhynchocephalia which mostly existed 200 million years ago. They live alongside dinosaurs
The name “tuatara” means “peaks on the back” in the Māori language.
The Brothers Island tuatara was listed as its own species in 1989. In 2009 this division was discontinued as research showed that is best described as a single species.
Burnie, D., 2011. Animal. 3rd ed. London: DKH
Jackson, T. and Chinery, M., 2012. The illustrated encyclopedia of animals of the world. London: Southwater.
Ambrose, J., 2015. Wildlife Of The World. 1st ed. London: Dorling Kindersley
itchmough, R. 2019. Sphenodon punctatus. The IUCN Red List of Threatened Species 2019: e.T131735762A120191347. https://dx.doi.org/10.2305/IUCN.UK.2019-2.RLTS.T131735762A120191347.en. Downloaded on 17 August 2021.
Doc.govt.nz. 2021. Tuatara. [online] Available at: <https://www.doc.govt.nz/nature/native-animals/reptiles-and-frogs/tuatara/> [Accessed 17 August 2021].