Tuatara, a lizardlike reptile found on several small islands off New Zealand. One species inhabits about 30 islands. In 1990, it was determined that a second species exists on one island.

Tuataras have remained almost unchanged for some 200 million years. Adults are greenish-brown above with gray or white speckles. The underparts are lighter. A crest of white spines grows along the neck and back. An adult male is about two feet (60 cm) long and weighs about two pounds (900 g); the female is smaller.

Tuataras are sluggish during the day but active at night when they hunt for such food as insects, spiders, snails, and earthworms. They live in burrows made by shore birds, especially petrels. In summer, the birds and the tuataras share the burrows. If a tuatara cannot find a bird burrow, it digs its own.

In spring, the female lays from 8 to 15 soft, white eggs that are about one inch (2.5 cm) long. The young hatch more than a year later and are about six inches (15 cm) long. Their bodies are brown or gray with stripes on the throat. Tuataras do not reach sexual maturity until they are about 20 years old. Some specimens have lived in captivity for more than 50 years. Many zoologists believe that in their natural habitat tuataras may live for more than 100 years.

Tuataras, which are endangered, are protected by the New Zealand government.

The two species of tuatara are Sphenodon punctatus and (the more recently named) S. guntheri. They are the only living members of the order Rhyncho-cephalia.