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Over the eons, millions of species have gone extinct naturally. Today, species headed toward extinction are generally helped along their way because of human activities. Enter the tuatara, an odd exception to the rule. Unlike most pending extinctions around the world, when the last tuatara is gone, humans will not be to blame. Most tuataras disappeared long before our time.  

Tuataras are the sole surviving species of an otherwise extinct taxonomic group of reptiles. For comparison with other living reptiles, several thousand species of snakes and lizards are alive today. A hundred million years ago, tuataras would not have been considered rare because, as verified by the fossil record, hundreds of species thrived throughout the world. Today they are restricted to a few cold, undeveloped islands off the New Zealand coast.

Tuataras look like big brown lizards but differ by having distinctive skeletal, dental and skull features. Their blood cells are larger than any other living reptile’s. Tuataras have the remnants of a third eye in the center of the skull; its function remains unclear to scientists. Another tuatara trait is vocalization. Hearing a tuatara croak on a cold, drizzly night on an uninhabited island a thousand miles from Australia might well evoke some primitive emotions tied to our own evolutionary past. They reportedly make a cricket-like sound when picked up.

A distinctive physiological difference between tuataras and all other living reptiles is that they require cool temperatures to survive. A well-known characteristic of other reptiles is that they are only active when they are warm, usually at temperatures between 60 and 80 degrees F. Some desert lizards thrive at temperatures above 100. A tuatara tolerates temperatures near freezing, is active around 45 degrees and will die at temperatures much above 80.

Tuataras reach lengths greater than 2 feet. They eat mostly small animals, along with bird eggs and a few small seabirds that nest on their islands. Classified as endangered, tuataras are carefully protected. They cannot be transported out of the country, even to zoos. Most Americans have never seen a live one; most New Zealanders have never seen one in the wild, as the islands themselves are nearly inaccessible.

Tuataras have a long life span. One was kept in captivity for 77 years, and learning that some individuals live more than a century would come as no surprise. Other age-related phenomena of importance are that these bizarre animals take up to two decades to reach maturity and more than half a century to attain full adult size. Female tuataras lay about a dozen eggs, but at intervals of 4 years. The eggs can take 15 months to hatch.

 Among the greatest threats to the remaining tuataras are nonnative rats that have been inadvertently introduced to the islands. A slow-growing reptile with a low reproductive output that has evolved without natural predators can become dependent on extended longevity to ensure successful reproduction. The arrival of a predator that can kill eggs and young of the tuatara could become a serious threat to the reptile’s continued existence. Sadly, these unusual reptiles are already extinct on a few of the rat-infested islands. Some conservation biologists contend that humans are culpable for the introduction of rats and the subsequent decline of tuataras. Sure, we have probably caused the disappearance of some tuataras, but these last remnants of this bizarre group of reptiles were on their way to extinction long before humans appeared on the scene. Most species of tuatara disappeared millions of years ago.

Tuataras represent a conservation situation different from ones that pit economics against the environment or self-serving individuals against public sentiment. Humans protect today’s tuataras as well as a wild animal can be protected. Other species of wildlife and other environments have been woefully neglected or actively mistreated by humans on a global scale, but when the last tuatara dies, we really shouldn’t blame ourselves.

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Caption: The sole surviving species of an ancient group of reptiles, a tuatara resembles a lizard but qualifies as a living fossil. Photo courtesy Peter Morrison, Department of Conservation, New Zealand