Tuatara come out on top of lifespan study

ageing slowly: Tuatara have a life span of 137 years, much longer than many other reptiles and amphibians. Picture by Sarah Lamar

The tuatara has emerged as one of the longest living reptiles in a new international study of cold-blooded critters.

The reptiles are endemic to Aotearoa and part of a distinct lineage, the order of Rhynchocephalia.

“Tuatara can live for an impressive 137 years — a feat humans can only aspire to,” Victoria University of Wellington professor and co-author of the study Nicky Nelson said.

The research compared the ageing rates of 77 cold-blooded, four-legged reptiles and amphibians.

The study was led by international researchers looking to assimilate some learnings from reptiles and amphibians.

“Tuatara represent a distinct lineage of reptiles that makes them different from all other living reptiles. It was an important species to have represented for comparison,” Professor Nelson said.

In contrast to the long life span of tuatara, the study found turtles live for about 39 years, crocodiles for 21, salamanders for 10 and frogs for eight years.

“Once tuatara are of adult size, they are very slow to age. However, not every individual gets the chance to survive to a ripe old age — especially those exposed to threats from rats and other introduced predators”.

Data on the tuatara comes from a 60-year study of a population of the reptiles on North Brother Island, a small rocky island in Cook Strait.

Professor Nelson said gathering the data involved a huge effort by researchers, including nights spent searching for tuatara and catching them by hand.

Findings of the international research may help us understand the ageing rates of New Zealand's other reptiles, she said.

“It's really important to know how long things can live so that we can understand the importance of factors that influence the viability of their populations.

“For example, living a long time could mean having lots of chances to reproduce, and reproductive success is important for maintaining populations. It will influence the decisions for captive holders considering the long-term commitment to caring for these animals.”

Professor Nelson said it would also influence the expectations for how long it could take to measure whether translocations have been successful.

Studies of natural populations will be better informed by this data point, particularly when considering, for example, climate warming influences on population viability.

“We have a large number of these animals, including 126 species of lizard, and we still have a lot to learn about them.”

Results suggest the rate at which reptiles age increases with mean environmental temperature, an important finding given current global warming.

Long life was also associated with physical or chemical traits, such as having a shell or producing venom.

The authors found these “protective traits” enabled animals to age more slowly and live longer.

The research highlighted the importance of long-term studies, particularly for species such as tuatara that live for more than 100 years.

“We have studied the population on North Brother Island for decades, giving us one of the longest datasets used in this international comparison.”