Species Fact Profile: Tuatara (Sphenodon punctatus)

Tuatara

Sphenodon punctatus (Gray, 1842)

Range: Off-Shore Islands of New Zealand
Habitat: Coastal Forests Scrub
Diet: Insects, Spiders, Snails, Worms, Lizards, Eggs, Small Birds, Carrion
Social Grouping: Solitary, Territorial During Breeding Season
Reproduction: Mate January through March, but female does not lay eggs until October or December.  18-19 eggs laid in a shallow hole; the female guards the nest for a few days before abandoning it.  Incubation is 11-16 months (longest of any reptile), sex is determined by incubation temperature (higher temperatures produce males, lower temperatures produce females).  Sexually mature at 9-13 years old.  Eggs laid every 4 years on average (in some locales, only every 9 years).
Lifespan: Over 100 Years
Conservation Status: IUCN Least Concern, CITES Appendix I

• Males grow up to 61 centimeters and weight 1 kilogram; females measure 45 centimeters and weight 500 grams.  Males also have a more triangular head and less pear-shaped body. 
• Skin is olive-green, gray, brown, or sometimes pinkish, marked with pale speckles that are brighter in juveniles than adults.  A row of spines runs down the length of the body ("tuatara" is Maori for "peaks on the back").  
• Though they look like lizards,tuatara are the only members of an ancient order to reptiles, the Rhynchocephalia ("Beak Heads").  Tuataras differ from lizards in their dentition, lack of external ear-openings, lack of a penis (males mate by holding their cloaca up to that of the female, in the manner of birds), and a primitive, light-sensitive "third-eye" on top of the head, beneath the skin
• Voice is a harsh croak, sometimes likened to the call of a frog
• Nocturnal, live in burrows either dug themselves or shared with seabirds; may emerge during the day to bask
• If seized by a predator, the tuatara can shed its tail and grow a new one
• Very low metabolic rate, which allows it to be active at cool temperatures, sometimes as low as 5 degrees Celsius
• Prominent in native folklore as messengers of god Whiro, Maori women would get tattoos of tuatara as signs of fertility
• There are three subspecies of tuatara, one of which (Brothers Island tuatara, S. p. guntheri) is sometimes described as a full species
• Major threat to the survival of tuatara has been the introduction of rats, which raid nests and eat eggs and small hatchlings (tuatara are very slow breeders, making it difficult to rebuild their populations), as well as the tuataras' food sources.  Once found throughout mainland New Zealand, but disappeared after the arrival of humans.
• Conservation efforts include the eradication of rats, as well as the introduction of wild and captive-bred tuatara onto rat-free islands
• Very rare in American zoos, captive breeding has so far only occurred in New Zealand

Zookeeper's Journal: I once read about a famous concert violinist who dressed up in street clothes and played a brief concert in a DC Metro station.  Very, very few of the hundreds of people who passed him by noticed, or stopped to realize how rare or unique that experience was.  I felt that way when I watched the tuataras in their display case at a zoo where I worked.  Few people saw them in the room-sized enclosure they occupied in the Reptile House, as they spent a lot of time in their burrows.  When they were seen, they were often dismissed as brownish iguanas, and no further attention was paid to one of the rarest, most remarkable reptiles in zoo collections.  Working with tuataras, what impressed me the most was how cold they were.  Their enclosure was chilled to fifty degrees Fahrenheit, compared to the 80s or 90s of other display cases, and their skin felt cool to the touch.  Handling one, they made me think of a beanie-baby left in a refrigerator.