On a series of small offshore islands in the southwest Pacific Ocean, an ancient beast offers any privileged enough to lay eyes on it a uniquely rare glimpse into the distant past. While a self-sufficient population of more than 60,000 specimens have survived into the twenty-first century Anno Domini, this species flourished in much greater numbers more than 200 million years ago during the Mesozoic Era - when dinosaurs ruled over the suddenly splintering supercontinent of Pangaea. As contemporaries like the Pterodactyl disappeared from the skies and Tyrannosaurus Rex from the ground, this creature adapted and endured through dramatic climate and geographical changes. Isolated from predators and safe from annihilation, the Tuatara has become a living and breathing reptilian time capsule.
The small coastal islands in New Zealand's Cook Strait and Bay of Plenty bear no resemblance to the fictional world Michael Crichton created in Jurassic Park. They are placid places, anything but amusement parks, strictly monitored and unobtrusively regulated. For scientists, Sphenodon punctatus and Sphenodon guntheri - the rarer subspecies exclusively found on North Brother Island - represent the truest "living fossils," touting an unbelievable array of traits unique among all extant animals on Earth.
Measuring an average of 53 centimeters (21 inches) and .75 kilograms (1.6 pounds), the Tuatara looks like nothing more than an unassuming lizard at first glance. Scaly skin ranges from hues of greenish brown to dark pink and is commonly mottled with white spots. A crest of small spines spans down the back and long tail, while two pairs of short legs - all ending in four sharp claws - extend from either side of the body. Even the carnivorous diet is inconspicuous, with small insects, invertebrates, reptiles, birds, and eggs filling out the menu. Only a closer examination of this endemic New Zealand reptile will reveal its stunning uniqueness.
By biological standards, most of the Tuatara's most exceptional attributes can be qualified as primitive. Lacking an eardrum and ear hole, the Tuatara senses sounds through loose fatty tissue that fills the middle ear cavity. Of all amniotes - a group encompassing all reptiles, birds, and mammals - the Tuatara is the only species with a spine made up of amphicoelous vertebrae, which are concavely shaped on both anterior and posterior, a trait more commonly synonymous with lesser evolved vertebrates like amphibians and fish. Internal organs display even more basic features: lungs function with just a single chamber and lack bronchi, while the heart is the least complex of any other reptile.
Whereas most animals develop replaceable teeth - separate entities unto themselves - the Tuatara touts an unconventional equivalent. Along the mouth's upper rim, two parallel rows of sharp serrations in the jawbone form forceful chewing surfaces, while a similar singular ridge on the bottom jaw wedges perfectly in between. In the former years of a Tuatara's extensive lifespan - which often ranges between 60 and 100 years - these sharp serrations can shear a bone. When repeatedly grinding exoskeletons and eggshells eventually takes it toll, however, these worn down chewers are relegated to mushy meals of worms, slugs, and larvae.
To survive on New Zealand's relatively chilly island nights, the nocturnal Tuatara have evolved with a dramatically lower body temperature than most reptiles. While their closest relatives maintain an average temperature of 20 degrees Celsius (68 Fahrenheit), Tuatara temperatures range between 5.2 and 11.2 degrees Celsius (41-52 Fahrenheit). Throughout most months of the year, individuals will only emerge in the sunlight to bask on rocks and restore body warmth during early morning hours. Come wintertime, Tuatara resort to a different practice: hibernation. Until spring returns, these ectotherms remain huddled in burrows originally built and later abandoned by various shorebirds; these shelters will continue to serve as home for the remainder of the year.
In the midst of summer's heat, Tuatara will commence their ancient mating rituals. Upon reaching sexual maturity after ten years, males will court females through a theatrical display - darkening their skin, raising their spiny crests, and parading in circles around their potential mate with stiffened legs. Consenting females permit their partners to mount them, but sexual intercourse does not ensue as it would for other reptiles. In similar fashion to birds, the male transfers his semen to the female through a cloacal kiss; lacking a penis, the male fertilizes the female by placing his vent - from which semen is excreted from - over her vent.
For females, due to the slowest reproduction cycle of any reptile, mating only occurs every four years. Only after anywhere between one and three years of developing enough yolk to adequately nourish her eggs, and an additional seven months of waiting for shells to form, can a female effectively mate. Following fertilization, female Tuatara will lay between five and eighteen soft, parchment-shelled eggs, which will not hatch for an additional twelve to fifteen months.
Unlike their parents, hatchlings assume a diurnal schedule to avoid cannibalistic consumption by their elders. Hiding under logs and stones, these tiny newborns learn to fend for themselves quickly. Resembling their parents in almost every way, Tuatara hatchlings display one striking feature in their earliest months of life: a parietal eye. More commonly called a "third eye," this distinctive attribute has its own lens, cornea, retina, and degenerated nerve connection to the brain - but it is only visible as a translucent patch at the top-center of hatchlings' skulls. Within six months, pigmented scales will conceal this eye from plain view.
Much like the Maori, all humans must treat that the Tuatara as taonga: a special treasure. When Polynesian rats invaded New Zealand, effectively exterminating the mainland Tuatara population, humans nearly lost one of the last windows into a world lost long ago. Through concerted conservation efforts on the more than thirty islands that the species still remains, the Tuatara population has not only significantly stabilized - it has begun to rebound.
Recently, the hope has reached new heights. In 2005, a small population of Tuatara were reintroduced to mainland New Zealand in Karori Sanctuary on North Island. Three years later, scientists discovered a nest with hatchlings - the first successful mainland breeding in at least two centuries for the species.
An adult Tuatara outside its nest hole on one of the islands in the Cook Strait, which are protected habitat areas. Drysoxylum spectabile , a New Zealand native tree is providing cover over the nest site. The Maori name for the plant is "Kokekohe", and fruits have begun to fall on the forest floor. The Tuatara is about to make a quick meal of another New Zealand native, one of the giant crickets called a Weta.
Endemic to more than thirty small New Zealand islands
Small insects, invertebrates, reptiles, birds, and eggs
Like a chameleon, the Tuatara has eyes that can independently focus. Both eyes are outfitted with three eyelids (including a nictitating membrane), a tapetum lucidum to enhance nocturnal vision, and specially adapted duplex retinas - which contain two types of visual cells, one set to see by day and one by night.
Tuatara develop slowly, continuing to grow throughout the first 35 years of their lives.
The Maori believed Tuatara were messengers from Whiro, the god of death. Women were forbidden from eating them.
The word Tuatara comes from the Maori language, meaning "peak on the back." Meanwhile, the genus name Sphenodon is Greek for "wedge tooth."
The Tuatara was formerly depicted on the New Zealand 5-cent coin, which was eliminated from the national currency in October 2006.