Animal Diversity Web

Ge­o­graphic Range

The two rec­og­nized species of tu­atara (Sphen­odon punc­ta­tus and Sphen­odon gun­theri) are found on ap­prox­i­mately 30 small, rel­a­tively in­ac­ce­si­ble, is­lands off the coast of New Zealand. The species was once widely dis­trib­uted through­out New Zealand, but be­came ex­tinct on the main­land be­fore the ar­rival of Eu­ro­pean set­tlers.

• Biogeographic Regions
• australian
  • native

Habi­tat

The ge­o­graphic range which the tu­atara in­hab­its is a dif­fi­cult niche for any species, par­tic­u­larly a rep­tile. The is­lands are gen­er­ally cliff-bound, fre­quently ex­posed to strong winds, and sup­port a nat­ural, often stunted, veg­e­ta­tion of salt and wind tol­er­ant species. Most is­lands are also home to sev­eral species of sea birds, whose nu­tri­ent-rich guano helps sup­port the is­land's ecosys­tem. The habi­tat is cold and damp, with tem­per­a­tures rarely ex­ceed­ing 70 de­grees Fahren­heit, and a hu­mid­ity level of about 80 per­cent. The tem­per­a­ture may often ap­proach freez­ing, but the tu­atara is able to main­tain nor­mal ac­tiv­i­ties at tem­per­a­tures as low as 45 de­grees Fahren­heit. Pre­ferred body tem­per­a­ture is be­tween 60 and 70 de­grees, this is the low­est op­ti­mal body tem­per­a­ture of all rep­tiles. At tem­per­a­tures above 76 de­grees, tu­ataras show signs of dis­tress, and most will die if the tem­per­a­ture ex­ceeds 82 de­grees.

• Terrestrial Biomes
• chaparral

Phys­i­cal De­scrip­tion

Tu­ataras may be grey, olive, or brick­ish red in color. They range in adult length from about 40 cm (fe­male) to 60 cm (large male), with the male gen­er­ally reach­ing larger pro­por­tions. They lack ex­ter­nal ears, have a di­ap­sid skull (two open­ings on ei­ther side), and posess a "pari­etal eye" on the top of their head. Other lizards also have this "third-eye," which con­tains a retina and is func­tion­ally sim­i­lar to a nor­mal eye, though the func­tion has not been clearly rec­og­nized and a scale grows over it in adult tu­ataras. The male tu­atara dis­plays a strik­ing crest down the back of the neck, and an­other down the mid­dle of the back. The fe­male has a less de­vel­oped ver­sion of this. Un­like all other liv­ing toothed rep­tiles, the tu­atara's teeth are fused to the jaw bone (acrodont tooth struc­ture). The tu­atara has a very slow me­tab­o­lism and is a very long-lived species. It's not un­com­mon for an in­di­vid­ual to live for over 100 years.

• Other Physical Features
• ectothermic
• bilateral symmetry

• Range mass

  0.4 to 1 kg

  0.88 to 2.20 lb

• Average basal metabolic rate

  0.0605 W

  AnAge

Re­pro­duc­tion

It takes be­tween 10 and 20 years for a tu­atara to reach sex­ual ma­tu­rity. The fe­male, on av­er­age, lays be­tween 5 and 18 eggs only once every 4 years, the longest re­pro­duc­tive cycle of any rep­tile. Mat­ing oc­curs from mid-sum­mer to early au­tumn (Jan­u­ary-March) and the eggs are laid the fol­low­ing spring or early sum­mer (Oc­to­ber-De­cem­ber). In­cu­ba­tion takes from 12 to 15 months, with the de­vel­op­ment of the em­bryo stop­ping dur­ing the win­ter months. Thus, a hatch­ling tu­atara would have been con­ceived over two years ear­lier. The male is de­void of any ex­ter­nal sex or­gans, and cop­u­la­tion is achieved by a meet­ing of the cloa­cal re­gions in what is known as a "cloa­cal kiss."

• Key Reproductive Features
• gonochoric/gonochoristic/dioecious (sexes separate)

• Average age at sexual or reproductive maturity (female)
  Sex: female

  4380 days

  AnAge

• Average age at sexual or reproductive maturity (male)
  Sex: male

  4380 days

  AnAge

Lifes­pan/Longevity

• Average lifespan
  Status: captivity

  35.0 years

  Max Planck Institute for Demographic Research

• Average lifespan
  Status: captivity

  77.0 years

  Max Planck Institute for Demographic Research

• Average lifespan
  Status: captivity

  50.0 years

  Max Planck Institute for Demographic Research

• Average lifespan
  Status: captivity

  11.7 years

  Max Planck Institute for Demographic Research

• Average lifespan
  Sex: male
  Status: captivity

  7.0 years

  Max Planck Institute for Demographic Research

Be­hav­ior

Tu­ataras live singly in bur­rows, which they some­times de­fend. Males com­bat each other, in­flat­ing their bod­ies, el­e­vat­ing their crests, and dark­en­ing the skin be­tween the shoul­ders and neck crest. Males also ap­proach fe­males in this man­ner prior to breed­ing. Tu­ataras are most ac­tive at night, but oc­ca­sion­ally bask at the en­trance to their bur­rows if it is sunny.

• Key Behaviors
• terricolous
• nocturnal
• motile
• solitary

Food Habits

Diet con­sist of arthro­pods, earth­worms, snails, bird eggs, small birds, frogs, and lizards, and a na­tive cricket-like in­sect the size of a mouse called a weta. Young tu­ataras are also oc­ca­sion­ally can­ni­bal­ized. Due to its low meta­bolic rate, the tu­atara eats much less fre­quently than other rep­tiles.

• Primary Diet
• carnivore
  • insectivore

• Animal Foods
• birds
• amphibians
• reptiles
• eggs
• insects
• terrestrial non-insect arthropods
• mollusks
• terrestrial worms

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Not known.

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

None known.

Con­ser­va­tion Sta­tus

In 1895, the coun­try of New Zealand awarded the tu­atara strict legal pro­tec­tion. It is cur­rently con­sid­ered a CITES (Con­ven­tion on the In­ter­na­tional Trade in En­dan­gered Species) Ap­pen­dix I species. This is the most re­stricted clas­si­fi­ca­tion for a species. In order for a zoo to pos­sess this species, very de­mand­ing rules must be fol­lowed, and the pub­lic dis­play of tu­ataras has only re­cently been al­lowed. Ac­cess to the is­lands that the tu­atara in­habit is strictly reg­u­lated, and for many years no tu­ataras have been re­moved from any is­land for any rea­son.

• IUCN Red List

  Lower Risk - Least Concern
  More information

• IUCN Red List

  Lower Risk - Least Concern
  More information

• US Federal List

  Endangered

• CITES

  Appendix I

Other Com­ments

The tu­atara is the only liv­ing de­scen­dent of the order of rep­tiles known as Rhyn­cho­cephalia. This fact dis­tin­guishes it from all other mod­ern day rep­tiles. Rhyn­cho­cephalians were a much larger order of rep­tiles a few hun­dred mil­lion years ago, with a con­sid­er­able num­ber of species dur­ing the Tri­as­sic pe­riod. All ex­cept for the tu­atara ap­par­ently went ex­tinct around 60 mil­lion years ago, in the late Cre­ta­ceous pe­riod. The tu­atara has been falsely called a liv­ing fos­sil. Though very sim­i­lar to its ex­tinct an­ces­tors, it has de­vel­oped fea­tures unique to its own mod­ern species. As well, it has been likened to a liv­ing di­nosaur, due to its di­ap­sid skull and other anatom­i­cal fea­tures shared with pre­his­toric rep­til­ians.

Con­trib­u­tors

Bruce Mu­sico (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

New­man, Don. 1987. "Tu­atara." En­dan­gered New Zealand Wildlife Se­ries. John McIn­doe, Lim­ited. Dunedin, New Zealand.

Wright, Kevin DVM. 1994. "Tu­ataras." Vol.2, No.1. Rep­tiles mag­a­zine. Fancy Pub­li­ca­tions. Irvine, Cal­i­for­nia.

Robb, J. 1977. The Tu­atara. Mead­ow­field Press, Lim­ited. Durham, Eng­land.