Tuatara (Sphenodon punctatus)

Description:

Photographed at Rainbow Springs Nature Park in Rotorua, New Zealand. Image ID: 5D-20051104-0996. A fascinating species! From the sign on the exhibit: "Tuatara (Sphenodon punctatus). The tuatara is a unique prehistoric reptile endemic to New Zealand. Often called a 'living fossil' it is believed to have survived here because of the absence of native land mammals. It has existed for over 225 million years and pre-dates the dinosaurs. In contrast human beings have existed for less than 3 million years....The tuatara is the only surviving sphenodontian, its last relative having died out 75 million years ago. The name sphenodon means 'wedge-toothed' and is a reference to its unusual tooth formation....They take up to 35 years to reach full size. Life span: 80-100 years on average but some are thought to live very much longer -- 300 years or more....Reproduction: Sexual maturity is reached in 10-15 years. Males are unique amongst reptiles for the lack of a copulatory organ...; transfer of sperm is achieved by direct contact of vents. Males can mate annually, females only every fourth year.... Parietal (pineal) spot; the so-called 'third eye': This unique feature is a vestige of a primitive eye located at top centre of the skull. Visible externally only on hatchlings, it appears as a small opaque patch. Beneath is a rudimentary lens and retina. Formation of an image is no longer possible but the 'eye' is believed to function as a light sensor through which the circadian rhythm (biological clock) is entrained by photo receptivity of the nervous tissue. General: In cold climates...tuatara can go for 6 months without feeding and may breathe only once an hour. Their normal heart rate is 9-10 beats per minute."