tuatara facts

Introducing the tuatara

Sometimes referred to as lizards, tuataras have remained mostly unchanged throughout their entire history - 220 million years. The most common species is known simply as tuatara (Sphenodon punctatus, Cook Strait tuatara), and about 50,000 of whom live on Takapourewa (Stephen's Island) in the Marlborough Sounds. Tuatara are also on the Trios Group of islands and again in the Marlborough Sounds. The only named sub-species of Sphenodon punctatus is Sphenodon punctatus punctatus, Northern tuatara. There is a small population living on Little Barrier Island, the rest are spread over 24 islands in the Hauraki Gulf, off Northland, the Coromandel Peninsula and the Bay of Plenty.

How they look...

The name tuatara means ‘peaks on the back’ - the spiny crest on their backs is made of triangular soft folds of skin, it is bigger in males than in females, and is stiffened for mating or aggressive display. The tuatara's greenish brown colour matches its environment, and can change over its lifetime. Tuatara shed their skin at least once per year as adults, and three or four times a year as juveniles.

Tuatara measure up to 80cm from head to tail-tip. Some unusual features of tuatara are:

• two rows of teeth in the upper jaw, overlapping one row on the lower jaw making them unique among living species
• eyes that focus independently
• a ‘third eye’, visible in hatchlings as a translucent patch at the top centre of the skull, and later covered with opaque scales and pigment.
• they can hear but have no external ear
• their skeletons have a number of unique features some of them remnants of their evolution from fish.

How they behave

Adult tuatara are terrestrial and nocturnal reptiles, though they will often bask in the sun to warm their bodies. Hatchlings hide under logs and stones during the day - because adults are cannibalistic. Tuatara thrive in temperatures much lower than those tolerated by most reptiles, hibernate during winter, and have the lowest body temperature of any reptile - giving them their slower metabolism.

Reproduction

• Tuatara can live for over 100 years. They reach sexual maturity in their early teens.
• They mate during late summer (March) and lay their eggs in spring (October).
• Because female tuatara only mate every 2-4 years, competition for a mate is very high, and males use elaborate courtship displays to impress females.
• Females lay clutches of up to 20 eggs in holes they dig in the ground and carefully cover. The leathery-shelled eggs incubate for 11-16 months, with ground temperatures deciding the sex of the hatchlings.

Lifestyle

• Tuatara live alongside burrowing seabirds such as petrels, prions and shearwaters using the birds’ burrows for shelter or dig their own.
• They eat insects and spiders, frogs, lizards, birds’ eggs and chicks.
• Both male and female tuatara are highly territorial and will aggressively defend their territories. Tuatara can bite and don’t let go easily.

Threats to tuatara

Aotearoa-New Zealand evolved from the ancient continent of Gondwanaland, with a unique fauna of flightless birds, large insects and reptiles like the tuatara - but no native mammalian predators. This changed when Maori arrived about 800AD with the Kiore (Polynesian rat). In the 18th and 19th Centuries sealers, whalers and settlers brought the larger Norway rats and ship rats. Rats eating the eggs and the young pose the most serious threat to the survival of tuatara, and to many New Zealand birds.
Adult tuatara can co-exist with kiore, but they eventually die out as the rats rob nests of eggs and small hatchlings. Slow breeders, tuatara cannot make up for the losses.
The other species of rats are ‘nature's vandals', eating and destroying food sources and breeding prolifically when food is plentiful. Islands with rats have few nocturnal invertebrates or reptiles.

Conservation

Conservation initiatives focus on keeping existing habitats free of rodents and re-introducing tuatara to new habitats on rodent-free islands. Being slow-moving by nature tuatara are not unduly worried by captivity and can be successfully bred. There are several breeding programmes around Aotearoa-New Zealand, rearing animals that play an important part in conservation, education and research.

Cultural Significance

Tuatara are mentioned in several Maori legends, and are regarded as the messengers of Whiro, the god of death and disaster. Today, tuatara are regarded as a taonga (treasure). The tuatara was featured on one side of the New Zealand five cent coin, which was phased out in October 2006.