Tuatara: The Strangest of the Reptiles

Reptiles form one of the four major classes of superclass tetrapoda. There are four orders in this class, namely chelonia or testudinia (tortoises, turtles and terrapins), crocodilia (crocodiles, alligators and gavials) squamata (snakes and lizards) and the last one is rhincocephalia (only two living species of tuatara are there ). Tuataras are the rarest reptiles on the earth and they are considered to be critically endangered and carefully conserved in New Zealand.

Even though the external appearance of the tuatara looks like a lizard, they are not lizards. There are two species, Sphenodon punctuatus and Sphenodon guntheri, both of which belong to the same family sphenodontidae, which is in fact the only extant family of this order. They are considered to be the most primitive of all the reptiles. Their brain and mode of locomotion are almost similar to those of the amphibians. They are sexually dimorphic and males are larger than the females. The males are about two feet longer and females are about one and a half feet (Sphenodon punctatus). Their weights are respectively 1 kg and 500 grams. The brother island tuatara (Sphonodon guntheri) is relatively smaller, weighing over 660 g and 300 g (male and female respectively).

The difference between the lizards and tuataras lies in the structure of their skull. Their quadrate bone is fixed, like that of testudines (tortoises), but that of the lizards is movable. This difference in the skull structure is responsible for placing it in separate order. These reptiles are considered as one of the most bizarre of the reptiles, because it is believed that they haven’t changed much for many millions of years.

The lifespan of the tuataras is quite long. Their average lifespan can be compared to that of human beings, because it is quite common for them to live up to 70-80 years. There is a record of a tuatara having lived up to 111 years and it also fathered at that age! That is really an astonishing thing.

The tuataras are capable of staying active even at unusually low temperatures. Usually most of the reptiles go to hibernation when the temperature drops below 15⁰ Celsius but tuatara can be active even at temperature of up to 5⁰ Celsius.

The word ‘punctatus’ means spotted. This name was given to the main island tuatara before the second species, brother island tuatara, were discovered. These are later named as Sphenodon guntheri after the scientist who discovered them, Albert Gunther.