Tuatara


Description and biology

The tuatara (pronounced too–a–TAR–a) is a lizardlike reptile. It is olive green and speckled with yellow. It has a medium–sized head and a strong tail. The tuatara’s feet and hands each have five clawed digits (toelike projections). A crest of soft spines stretches along its back to the base of its tail.

An average female tuatara measures 20 inches (51 centimeters) long and weighs about 1 pound (0.45 kilogram). An average male measures 24 inches (61 centimeters) in length and weighs about 2.6 pounds (1.2 kilograms).

The tuatara has certain physical characteristics that separate it from lizards. Among other things, it has extra holes in its skull and bony projections on its ribs. Males of the species lack a copulating (breeding) organ.

It has a single row of teeth in its lower jaw and a double row in its upper jaw. When the tuatara’s mouth is closed, its bottom row of teeth fit neatly between its upper two rows. None of these teeth are replaced when worn out or damaged. This reptile also has a third eye—called a pineal eye—on the top of its head.

The eye contains a simplistic lens and retina and is connected to the brain by a nerve. Since this eye is covered by opaque scales, not much light gets through. Some biologists (people who study living organisms) believe the eye may function as a light sensor, determining how much time the tuatara spends basking in sunlight.

The tuatara is mainly nocturnal (active at night). It feeds on worms, snails, beetles, crickets, birds’ eggs, small lizards, and frogs. During the day, when not basking in the sun, the tuatara spends time in burrows built as nests by shearwaters and petrels (both sea birds).

Since males do not have copulating organs, tuataras breed like birds. When mating, a male and female bring their cloacae into contact. A cloaca (pronounced klow–AH–ka) is a cavity in the body of birds, reptiles, amphibians, and most fishes that has an opening to the outside through which sperm and body wastes such as feces pass.

Once having mated, a female tuatara lays a clutch of 6 to 10 eggs in a burrow or tunnel sometime between October and December. The female abandons the eggs after covering them with soil and the eggs hatch 13 to 15 months later. Tuataras can live up to 100 years. Habitat and current distribution

The tuatara is found on about 30 islands around New Zealand. Biologists estimate that the current tuatara population is between 60,000 and 100,000. More than half of all tuataras exist on Stephens Island.

On its island habitat, the tuataras is found in forest or dense scrub areas from sea level to an altitude 1,000 feet (305 meters) above sea level.

History and conservation measures

Tuataras are the most ancient of all living reptiles. They are the last surviving members of a family of reptiles that stretches back to the early Mesozoic Era, about 200,000,000 years ago.

During the age of reptiles, tuataras lived alongside dinosaurs. With the extinction of the dinosaurs 65,000,000 years ago, the age of mammals began and the tuatara soon disappeared from everywhere on Earth except New Zealand.

Humans first came to the New Zealand islands from nearby Polynesian islands sometime between 1,000 and 2,000 years ago. They brought with them the kiore, or Polynesian rat.

The kiore quickly became a predator of tuatara eggs and young. As more humans came to the New Zealand islands, bringing with them predators such as pigs and cats, the tuatara suffered. By the end of the nineteenth century, the reptile had become extinct on the main islands of New Zealand.

Efforts are currently underway to remove rats from tuatara island habitats. On the island of Tiritiri Matangi, all rats have now been eliminated. The island now teems with rich plant life, insects, lizards, forest birds, and tuataras. All islands on which tuataras are found are designated either wildlife sanctuaries or flora and fauna reserves. Both of these designations limit the number of humans who can visit these islands.

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