Ryan Photographic - Sphenodon punctatus - Tuatara

Sphenodontids

Family Sphenodontidae

Tuatara are found only in New Zealand. Two species, Sphenodon punctatus and the Brother's Island tuatara S. guntheri are recognized by many authorities, although a recent study suggests that the genetic differences between the two are insufficient to justify full species status for S. guentheri.

My introduction to tuatara came when I was 13. Together with a friend (Richard Rowe) we investigated Maori middens in the far north of North Island in Spirit Bay. We found them loaded with tuatara jaw bones, suggesting they were an important part of the local Maori diet. Alas, this penchant of chowing on tuatara (men only apparently), along with the Maori introduction of the Polynesian rat (kiore, Rattus exulans) soon led to their demise from the main islands. They survived on offshore islands. European arrival brought more rat species and where they, and kiore, made it ashore the tuatara population suffered. Only 8 tuatara were found on Little Barrier Island during 1991-1992 and only a captive breeding program and aggressive rat control, leading to eradication, saved the population. A similar scenario played out on several other islands.

Tuatara are the sole survivors of a once widespread reptilian order, the Rhyncocephalia. This biological classification gives tuatara equal status to the snakes, tortoises and turtles, crocodilians and lizards. Because of their relatively slow metabolism and extraordinary long life (some folk believe tuatara can live to 200 years in captivity) tuatara were often considered evolutionary oddities, destined for extinction, because of an inability to cope with the stresses of altered modern ecosystems. However, analysis of DNA from old tuatara bones and comparison with modern tuatara have shown extremely rapid evolutionary rates - in fact the fastest of any animal yet studied. Appearances can be deceptive (never judge a book by its cover - and as many similar homilies as you can think of).

I will long cherish my visit to Takapourewa (Stephens Island) in Cook Strait. I was able to take my Dad and my daughters Sarah and Lucy. Friend Richard de Hamel, who was Department of Conservation manager on the island, met us as we disembarked from our hired launch and made the long climb to our house. As we approached the house I complained to Richard that I hadn't yet seen a tuatara and the island was supposed to be crawling with them. "Turn over that sheet of corrugated iron" was his laconic response. I did so, and underneath it was the first wild tuatara I had ever seen. It was of course, the first of many. That night after dinner with Richard and his family, we made our way back to our house. We'd left a light on and the door open to make locating the place a little easier. Scrabbling sounds greeted us and when we entered it was to find around a dozen large tuatara chasing insects attracted by the light. Tuatara can bite quite savagely and will autotomize their tail if severely threatened, so picking them up was out of the question. In the end I picked up a broom and swept them out before closing the door.

We got to see many tuatara during our stay. Several encounters were a little on the gory side. Returning to our house one night we met a tuatara walking along the trail with a fairy prion in its jaws, apparently bent on dragging it back to its burrow where it could be consumed at leisure. On another occasion I photographed a tree weta (a giant ground cricket) which jumped off the tree. Pretty much the instant it hit the gound there was a blur of grey and it was snapped up by a tuatara - I had no idea they could move that fast. The weta didn't go quietly - it buried its jaws into the flesh around the tuatara eye and held on with its powerful legs. The tuatara won in the end.

Tuatara have the lngest known incubation period of any reptile - 11 - 16 months. In the early days many a clutch of tuatara eggs were probably thrown out as infertile. Legend has it that a researcher collected a batch of eggs and incubated them for several months. Frustrated by the lack of any sign of development he put them in his desk drawer. Months later he heard a noise, opened the drawer to find a herd of baby tuatara charging around. As in many other reptiles sex ratio at hatching is determined by incubation temperature, warmer temperatures produce males, cooler temperatures produce females.

Young tuatara have a pronounced parietal eye (a third eye). This has all the attributes of an eye except that the nerves connecting it to the brain have somewhat degenerated. It is covered by a transparent scale which becomes opaque by the time the animal is six months old. We still don't know what, if anything, the parietal eye is used for.

I take great delight in teaching my zoology students that the tuatara is the only reptile that lacks a penis ...

Sphenodon punctatus Tuatara

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