Tuatara
Encyclopedia
The tuatara is a reptile
endemic to New Zealand
which, though it resembles most lizard
s, is actually part of a distinct lineage, order Sphenodontia
. The two species of tuatara are the only surviving members of its order, which flourished around 200 million years ago. Their most recent common ancestor with any other extant group is with the squamates
(lizards and snake
s). For this reason, tuatara are of great interest in the study of the evolution of lizards and snakes, and for the reconstruction of the appearance and habits of the earliest diapsid
s (the group that also includes bird
s, dinosaur
s, and crocodile
s).
Tuatara are greenish brown, and measure up to 80 cm (31.5 in) from head to tail-tip and weigh up to 1.3 kilograms (2.9 lb) with a spiny crest along the back, especially pronounced in males. Their dentition, in which two rows of teeth in the upper jaw overlap one row on the lower jaw, is unique among living species. They are further unusual in having a pronounced photo-receptive eye dubbed the "third eye", whose current function is a subject of ongoing research but is thought to be involved in setting circadian and seasonal cycles. They are able to hear although no external ear is present, and have a number of unique features in their skeleton, some of them apparently evolutionarily retained from fish. Although tuatara are sometimes called "living fossil
s", recent taxonomic and molecular work has shown that they have changed significantly since the Mesozoic
era.
The name "tuatara" derives from the Māori language
, and means "peaks on the back". As with many other Māori loanwords, the plural form is now generally the same as the singular in formal New Zealand English usage. "Tuataras" remains common in less formal speech, particularly among older speakers. The tuatara has been protected by law since 1895 (the second species, S. guntheri, was not recognised until 1989). Tuatara, like many of New Zealand's native animals, are threatened by habitat loss and introduced predators like the Polynesian Rat
(Rattus exulans). They were extinct on the mainland, with the remaining populations confined to 32 offshore islands, until the first mainland release into the heavily fenced and monitored Karori Sanctuary
in 2005.
During routine maintenance work at Karori Sanctuary in late 2008, a tuatara nest was uncovered, with a hatchling found the following autumn. This is thought to be the first case of tuatara successfully breeding on the New Zealand mainland in over 200 years, outside of captive rearing facilities.
(which includes lizards, snakes and amphisbaenia
ns), belong to the superorder Lepidosauria
, the only surviving taxon within Lepidosauromorpha
. Squamates and tuatara both show caudal autotomy (loss of the tail-tip when threatened), and have a transverse cloacal slit. The origin of the tuatara probably lies close to the split between the Lepidosauromorpha and the Archosauromorpha
. Though tuatara resemble lizards, the similarity is superficial, because the family has several characteristics unique among reptile
s. The typical lizard shape is very common for the early amniotes; the oldest known fossil of a reptile, the Hylonomus
, resembles a modern lizard.
Tuatara were originally classified as lizards in 1831 when the British Museum
received a skull. The genus remained misclassified until 1867, when Albert Günther
of the British Museum noted features similar to birds, turtles, and crocodiles. He proposed the order Rhynchocephalia (meaning "beak head") for the tuatara and its fossil relatives. Now, most authors prefer to use the more exclusive order name of Sphenodontia for the tuatara and its closest living relatives.
Many disparately related species were subsequently added to the Rhynchocephalia, resulting in what taxonomists call a "wastebasket taxon". Williston
proposed the Sphenodontia to include only tuatara and their closest fossil relatives in 1925. Sphenodon is derived from the Greek for "wedge" (σφηνος/sphenos) and "tooth" (δόντι/odon(t)).
Tuatara have been referred to as living fossil
s, which means their group retains many basal characteristics from around the time of the squamate – rhynchocephalian split (220 MYA). However, taxonomic
work on Sphenodontia has shown that this group has undergone a variety of changes throughout the Mesozoic
, and a recent molecular study showed that their rate of molecular evolution is faster than of any other animal so far examined. Many of the niches occupied by lizards today were then held by sphenodontians. There was even a successful group of aquatic sphenodontians known as pleurosaurs
, which differed markedly from living tuatara. Tuatara show cold weather adaptations that allow them to thrive on the islands of New Zealand; these adaptations may be unique to tuatara since their sphenodontian ancestors lived in the much warmer climates of the Mesozoic
.
in Cook Strait
. The species name punctatus is Latin for "spotted", and guntheri refers to Albert Günther. S. punctatus was named when only one species was known, and its name is misleading, since both species can have spots. The Brother's Island tuatara (S. guntheri) has olive brown skin with yellowish patches, while the colour of the other species, (S. punctatus), ranges from olive green through grey to dark pink or brick red, often mottled, and always with white spots. In addition, S. guntheri is considerably smaller. A third, extinct species of Sphenodon was identified in November 1885 by William Colenso, who was sent an incomplete sub-fossil specimen from a local coal mine. Colenso named the new species S. diversum. Sphenodon punctatus is further divided into two subspecies: the Cook Strait tuatara (unnamed subspecies), which lives on other islands in and near Cook Strait, and the northern tuatara (Sphenodon punctatus punctatus), which lives on the Bay of Plenty
, and some islands further north. A 2009 paper reexamined the genetic bases used to distinguish the two species of tuatara, and concluded that they only represent geographic variants, and only one species should be recognized.
The tuatara is considered the most unspecialised living amniote
; the brain and mode of locomotion resemble that of amphibians and the heart is more primitive than that of any other reptile. Their lungs have a single chamber and lack bronchi.
Both species are sexually dimorphic
, males being larger. Adult S. punctatus males measure 61 cm (24 in) in length and females 45 cm (17.7 in). The San Diego Zoo even cites a length of up to 80 cm (31.5 in). Males weigh up to 1 kg (2.2 lb), and females up to 0.5 kg (1.1 lb). Brother's Island tuatara are slightly smaller, weighing up to 660 g (1.3 lb).
The tuatara's greenish brown colour matches its environment, and can change over its lifetime. Tuatara shed their skin at least once per year as adults, and three or four times a year as juveniles. Tuatara sexes differ in more than size. The spiny crest on a tuatara's back, made of triangular soft folds of skin, is larger in males, and can be stiffened for display. The male abdomen is narrower than the female's.
and tortoise
) skulls, which lack any temporal fenestra (anapsid condition), are sometimes considered to be the most primitive among amniotes, though there is strong evidence they may have lost the temporal holes rather than never having had them.
The tip of the upper jaw is beak-like and separated from the remainder of the jaw by a notch. There is a single row of teeth in the lower jaw and a double row in the upper, with the bottom row fitting perfectly between the two upper rows when the mouth is closed. This specific tooth arrangement is not seen in any other reptile; although most snake
s have a double row of teeth in their upper jaw, their arrangement and function is different from the tuatara's. The jaws, joined by ligament
, chew with backwards and forwards movements combined with a shearing up and down action. The force of the bite is suitable for shearing chitin
and bone. The tuatara's teeth are not replaced, since they are not separate structures like real teeth, but sharp projections of the jaw bone. As their teeth wear down, older tuatara have to switch to softer prey such as earthworm
s, larva
e, and slug
s, and eventually have to chew their food between smooth jaw bones. The brain of Sphenodon fills only half of the volume of its endocranium
. This proportion has been used by paleontologists trying to estimate the volume of dinosaur brains based on fossils. The use of tuataras as a model animal for dinosaur brain volume has been criticized because since bird brains occupy a greater portion of their skulls, and dinosaurs are the ancestors of birds, at least some dinosaurs must have had volumes intermediate between the two.
independently, and are specialized with a duplex retina
that contains two types of visual cells for both day and night vision, and a tapetum lucidum
which reflects on to the retina to enhance vision in the dark. There is also a third eyelid on each eye, the nictitating membrane
.
The tuatara has a third eye on the top of its head called the parietal eye
. It has its own lens, cornea, retina
with rod-like structures, and degenerated nerve connection to the brain, suggesting it evolved from a real eye. The parietal eye is only visible in hatchlings, which have a translucent patch at the top centre of the skull. After four to six months it becomes covered with opaque scales and pigment. Its purpose is unknown, but it may be useful in absorbing ultraviolet
rays to manufacture vitamin D
, as well as to determine light/dark cycles, and help with thermoregulation
. Of all extant tetrapods, the parietal eye is most pronounced in the tuatara. The parietal eye is part of the pineal complex, another part of which is the pineal gland
, which in tuatara secretes melatonin at night. It has been shown that some salamanders use their pineal body to perceive polarised light, and thus determine the position of the sun, even under cloud cover, aiding navigation.
Together with turtle
s, the tuatara has the most primitive hearing organs among the amniotes. There is no eardrum
and no earhole, and the middle ear
cavity is filled with loose tissue, mostly adipose (fatty) tissue
. The stapes comes into contact with the quadrate
(which is immovable) as well as the hyoid
and squamosal
. The hair cell
s are unspecialized, innervated by both afferent
and efferent nerve
fibres, and respond only to low frequencies. Even though the hearing organs are poorly developed and primitive with no visible external ears, they can still show a frequency response from 100–800 Hz
, with peak sensitivity of 40 dB
at 200 Hz.
is made up of hourglass-shaped amphicoelous vertebrae, concave both before and behind. This is the usual condition of fish vertebrae and some amphibians, but is unique to tuatara within the amniotes.
The tuatara has gastralia
, rib-like bones also called gastric or abdominal ribs, the presumed ancestral trait of diapsids. They are found in some lizard
s, where they are mostly made of cartilage, as well as crocodiles and the tuatara, and are not attached to the spine or thoracic ribs. The true ribs are small projections, with small, hooked bones, called uncinate processes, found on the rear of each rib. This feature is also present in birds. The tuatara is the only living tetrapod
with well-developed gastralia and uncinate processes.
In the early tetrapods, the gastralia and ribs with uncinate processes, together with bony elements such as bony plates in the skin (osteoderms) and clavicle
s (collar bone), would have formed a sort of exo-skeleton around the body, protecting the belly and helped to hold in the guts and inner organs. These anatomical details most likely evolved from structures involved in locomotion even before the vertebrates ventured onto land. The gastralia may have been involved in the breathing process in early amphibians and reptiles. The pelvis and shoulder girdles are arranged differently to those of lizards, as is the case with other parts of the internal anatomy and its scales.
and nocturnal reptiles, though they will often bask in the sun to warm their bodies. Hatchlings hide under logs and stones, and are diurnal, likely because adults are cannibalistic. Tuatara thrive in temperatures much lower than those tolerated by most reptiles, and hibernate
during winter. They remain active at temperatures as low as 5 °C (41 °F), while temperatures over 28 °C (82 °F) are generally fatal. The optimal body temperature for the tuatara is from 16 to 21 °C (60.8 to 69.8 F), the lowest of any reptile. The body temperature of tuatara is lower than that of other reptiles ranging from 5.2–11.2 °C (41.4–52.2 F) over a day, whereas most reptiles have body temperatures around 20 °C (68 °F). The low body temperature results in a slower metabolism
.
Burrowing seabirds such as petrel
s, prions
, and shearwater
s share the tuatara's island habitat during the bird's nesting season. The tuatara use the bird
's burrows for shelter when available, or dig their own. The seabirds' guano
helps to maintain invertebrate populations that tuatara predominantly prey on; including beetle
s, cricket
s, and spider
s. Their diet also consists of frog
s, lizard
s, and bird's eggs and chicks. The eggs and young of seabirds that are seasonally available as food for tuatara may provide beneficial fatty acids
. Tuatara of both sexes defend territories, and will threaten and eventually bite intruders. The bite can cause serious injury. Tuatara will bite when approached, and will not let go easily.
Tuatara reproduce very slowly, taking ten to twenty years to reach sexual maturity. Mating occurs in midsummer; females mate and lay egg
s once every four years. During courtship, a male makes his skin darker, raises his crests, and parades toward the female. He slowly walks in circles around the female with stiffened legs. The female will either submit, and allow the male to mount her, or retreat to her burrow. Males do not have a penis
; they reproduce by the male lifting the tail of the female and placing his vent
over hers. The sperm
is then transferred into the female, much like the mating process in birds.
Tuatara eggs have a soft, parchment-like shell. It takes the females between one and three years to provide eggs with yolk, and up to seven months to form the shell. It then takes between 12 and 15 months from copulation to hatching. This means reproduction occurs at two- to five-year intervals, the slowest in any reptile. Wild tuatara are known to be still reproducing at about 60 years of age—"Henry", a 111-year-old tuatara at Southland Museum in Invercargill
, New Zealand, became a father (possibly for the first time) on 23 January 2009.
The sex of a hatchling depends on the temperature
of the egg, with warmer eggs tending to produce male tuatara, and cooler eggs producing females. Eggs incubated at 21 °C (70 °F) have an equal chance of being male or female. However, at 22 °C (72 °F), 80% are likely to be males, and at 20 °C (68 °F), 80% are likely to be females; at 18 °C (64 °F) all hatchlings will be females. There is some evidence that sex determination in tuatara is determined by both genetic and environmental factors.
Tuatara probably have the slowest growth rates of any reptile, continuing to grow larger for the first 35 years of their lives. The average lifespan is about 60 years, but they can live to be well over 100 years old. Some experts believe that captive tuatara could live as long as 200 years.
s) had recently established on several of the islands, and tuatara were persisting, but not breeding, on these islands. Additionally, tuatara were much rarer on the rat-inhabited islands.
The recent discovery of a tuatara hatchling on the New Zealand mainland indicates that attempts to reestablish a breeding population on the mainland have had some success. The total population of tuatara of all species and subspecies is estimated to be greater than 60,000, but less than 100,000.
s in 1990 and 1991, and maintained in captivity to allow Polynesian rats to be eradicated on those islands. All three populations bred in captivity, and after successful eradication of the rats, all individuals including the new juveniles were returned to their islands of origin. In the 1991–92 season, Little Barrier Island was found to hold only eight tuatara, which were taken into in situ captivity, where females produced 42 eggs, which were incubated at Victoria University. The resulting offspring were subsequently held in an enclosure on the island, then released into the wild in 2006 after rats were eradicated there.
In the Hen and Chicken Islands
, Pacific rats were eradicated on Whatupuke in 1993, Lady Alice Island in 1994, and Coppermine Island in 1997. Following this program, juveniles have once again been seen on the latter three islands. In contrast, rats persist on Hen Island of the same group, and no juvenile tuatara had been seen there as of 2001. In the Alderman Islands
, Middle Chain Island holds no tuatara, but it is considered possible for rats to swim between Middle Chain and other islands that do hold tuatara, and the rats were eradicated in 1992 to prevent this. Another rodent eradication was carried out on the Rangitoto Islands east of D’Urville Island, to prepare for the release of 432 Cook Strait tuatara juveniles in 2004, which were being raised at Victoria University as of 2001.
, a more publicly accessible location within Wellington Harbour. The captive juveniles were from induced layings from wild females.
In late October 2007, it was announced that 50 tuatara collected as eggs from North Brother Island and hatched at Victoria University were being released onto Long Island in the outer Marlborough Sounds
. The animals had been cared for at Wellington Zoo for the last five years and have been kept in secret in a specially built enclosure at the zoo, off display.
from Middle Island in the Mercury group
. They are occasionally seen sunbathing by visitors to the island.
A mainland release of S. punctatus occurred in 2005 in the heavily fenced and monitored Karori Sanctuary
. The second mainland release took place in October 2007, when a further 130 were transferred from Stephens Island
to the Karori Sanctuary. In early 2009 the first recorded wild-born offspring were observed.
in Invercargill
, was the first to have a tuatara breeding programme; they breed Sphenodon punctatus. Hamilton Zoo
, Auckland Zoo
and Wellington Zoo
also breed tuatara for release into the wild. The Victoria University of Wellington
maintains a research programme into the captive breeding of tuatara, and the Pukaha Mount Bruce Wildlife Centre
keeps a pair and a juvenile. The WildNZ Trust has a tuatara breeding enclosure at Ruawai
. On 28 January 2009, the 11th of 11 eggs belonging to tuataras Henry and Mildred hatched. This rare occurrence came after Henry had surgery to remove a cancerous tumor that was inhibiting both his ability and desire to breed.
, the god
of death and disaster, and Māori women are forbidden to eat them. Tuatara also indicate tapu (the borders of what is sacred and restricted), beyond which there is mana, meaning there could be serious consequences if that boundary is crossed. Māori women would sometimes tattoo images of lizards, some of which may represent tuatara, near their genitals. Today, tuatara are regarded as a taonga
(special treasure).
The tuatara was featured on one side of the New Zealand 5 cent coin, which was phased out in October 2006. Tuatara was also the name of the Journal of the Biological Society of Victoria University College and subsequently Victoria University of Wellington
, published from 1947 until 1993. It has now been digitised by the New Zealand Electronic Text Centre
, also at Victoria.
Australia
Europe
United States
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
endemic to New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
which, though it resembles most lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s, is actually part of a distinct lineage, order Sphenodontia
Sphenodontia
Sphenodontia is an order of lizard-like reptiles that includes only one living genus, the tuatara , and only two living species...
. The two species of tuatara are the only surviving members of its order, which flourished around 200 million years ago. Their most recent common ancestor with any other extant group is with the squamates
Squamata
Squamata, or the scaled reptiles, is the largest recent order of reptiles, including lizards and snakes. Members of the order are distinguished by their skins, which bear horny scales or shields. They also possess movable quadrate bones, making it possible to move the upper jaw relative to the...
(lizards and snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...
s). For this reason, tuatara are of great interest in the study of the evolution of lizards and snakes, and for the reconstruction of the appearance and habits of the earliest diapsid
Diapsid
Diapsids are a group of reptiles that developed two holes in each side of their skulls, about 300 million years ago during the late Carboniferous period. Living diapsids are extremely diverse, and include all crocodiles, lizards, snakes, and tuatara...
s (the group that also includes bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s, dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s, and crocodile
Crocodile
A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...
s).
Tuatara are greenish brown, and measure up to 80 cm (31.5 in) from head to tail-tip and weigh up to 1.3 kilograms (2.9 lb) with a spiny crest along the back, especially pronounced in males. Their dentition, in which two rows of teeth in the upper jaw overlap one row on the lower jaw, is unique among living species. They are further unusual in having a pronounced photo-receptive eye dubbed the "third eye", whose current function is a subject of ongoing research but is thought to be involved in setting circadian and seasonal cycles. They are able to hear although no external ear is present, and have a number of unique features in their skeleton, some of them apparently evolutionarily retained from fish. Although tuatara are sometimes called "living fossil
Living fossil
Living fossil is an informal term for any living species which appears similar to a species otherwise only known from fossils and which has no close living relatives, or a group of organisms which have long fossil records...
s", recent taxonomic and molecular work has shown that they have changed significantly since the Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
era.
The name "tuatara" derives from the Māori language
Maori language
Māori or te reo Māori , commonly te reo , is the language of the indigenous population of New Zealand, the Māori. It has the status of an official language in New Zealand...
, and means "peaks on the back". As with many other Māori loanwords, the plural form is now generally the same as the singular in formal New Zealand English usage. "Tuataras" remains common in less formal speech, particularly among older speakers. The tuatara has been protected by law since 1895 (the second species, S. guntheri, was not recognised until 1989). Tuatara, like many of New Zealand's native animals, are threatened by habitat loss and introduced predators like the Polynesian Rat
Polynesian Rat
The Polynesian Rat, or Pacific Rat , known to the Māori as kiore, is the third most widespread species of rat in the world behind the Brown Rat and Black Rat. The Polynesian Rat originates in Southeast Asia but, like its cousins, has become well travelled – infiltrating Fiji and most Polynesian...
(Rattus exulans). They were extinct on the mainland, with the remaining populations confined to 32 offshore islands, until the first mainland release into the heavily fenced and monitored Karori Sanctuary
Karori Wildlife Sanctuary
Zealandia, formerly known as the Karori Wildlife Sanctuary, is a protected natural area in Wellington, New Zealand, where the biodiversity of 225 ha of forest is being restored...
in 2005.
During routine maintenance work at Karori Sanctuary in late 2008, a tuatara nest was uncovered, with a hatchling found the following autumn. This is thought to be the first case of tuatara successfully breeding on the New Zealand mainland in over 200 years, outside of captive rearing facilities.
Taxonomy and evolution
Tuatara, and their sister group SquamataSquamata
Squamata, or the scaled reptiles, is the largest recent order of reptiles, including lizards and snakes. Members of the order are distinguished by their skins, which bear horny scales or shields. They also possess movable quadrate bones, making it possible to move the upper jaw relative to the...
(which includes lizards, snakes and amphisbaenia
Amphisbaenia
The Amphisbaenia are a usually legless suborder of squamates closely related to lizards and snakes. As many species possess a pink body coloration and scales arranged in rings, they have a superficial resemblance to earthworms. They are very poorly understood, due to their burrowing lifestyle...
ns), belong to the superorder Lepidosauria
Lepidosauria
The Lepidosauria are reptiles with overlapping scales. This subclass includes Squamata and Sphenodontidae. It is a monophyletic group and therefore contains all descendents of a common ancestor. The squamata includes snakes, lizards, tuataras, and amphisbaenia. Lepidosauria is the sister taxon...
, the only surviving taxon within Lepidosauromorpha
Lepidosauromorpha
Lepidosauromorpha is a group of reptiles comprising all diapsids closer to lizards than to archosaurs . The only living sub-group is the Lepidosauria: extant lizards, snakes, and tuatara...
. Squamates and tuatara both show caudal autotomy (loss of the tail-tip when threatened), and have a transverse cloacal slit. The origin of the tuatara probably lies close to the split between the Lepidosauromorpha and the Archosauromorpha
Archosauromorpha
Archosauromorpha is an infraclass of diapsid reptiles that first appeared during the late Permian and became more common during the Triassic. Included in this infraclass are the groups Rhynchosauria, Trilophosauridae, Prolacertiformes, Archosauriformes, and, tentatively, Choristodera...
. Though tuatara resemble lizards, the similarity is superficial, because the family has several characteristics unique among reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
s. The typical lizard shape is very common for the early amniotes; the oldest known fossil of a reptile, the Hylonomus
Hylonomus
Hylonomus was a very early reptile. It lived 312 million years ago during the Late Carboniferous period.It is the earliest unquestionable reptile ....
, resembles a modern lizard.
British Museum
The British Museum is a museum of human history and culture in London. Its collections, which number more than seven million objects, are amongst the largest and most comprehensive in the world and originate from all continents, illustrating and documenting the story of human culture from its...
received a skull. The genus remained misclassified until 1867, when Albert Günther
Albert C. L. G. Günther
Albert Karl Ludwig Gotthilf Günther FRS, also Albert Charles Lewis Gotthilf Günther , was a German-born British zoologist, ichthyologist, and herpetologist....
of the British Museum noted features similar to birds, turtles, and crocodiles. He proposed the order Rhynchocephalia (meaning "beak head") for the tuatara and its fossil relatives. Now, most authors prefer to use the more exclusive order name of Sphenodontia for the tuatara and its closest living relatives.
Many disparately related species were subsequently added to the Rhynchocephalia, resulting in what taxonomists call a "wastebasket taxon". Williston
Samuel Wendell Williston
Samuel Wendell Williston was an American educator and paleontologist who was the first to propose that birds developed flight cursorially , rather than arboreally . He was also an entomologist, specialising in Diptera.-Early life:Williston was born in Boston, Massachusetts to Samuel Williston and...
proposed the Sphenodontia to include only tuatara and their closest fossil relatives in 1925. Sphenodon is derived from the Greek for "wedge" (σφηνος/sphenos) and "tooth" (δόντι/odon(t)).
Tuatara have been referred to as living fossil
Living fossil
Living fossil is an informal term for any living species which appears similar to a species otherwise only known from fossils and which has no close living relatives, or a group of organisms which have long fossil records...
s, which means their group retains many basal characteristics from around the time of the squamate – rhynchocephalian split (220 MYA). However, taxonomic
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
work on Sphenodontia has shown that this group has undergone a variety of changes throughout the Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
, and a recent molecular study showed that their rate of molecular evolution is faster than of any other animal so far examined. Many of the niches occupied by lizards today were then held by sphenodontians. There was even a successful group of aquatic sphenodontians known as pleurosaurs
Pleurosaurus
Pleurosaurus is an extinct genus of diapsid reptile belonging to the order Sphenodontia, and therefore related to the modern tuatara. Pleurosaurus fossils were discovered in the Solnhofen limestone formation of Bavaria, Germany....
, which differed markedly from living tuatara. Tuatara show cold weather adaptations that allow them to thrive on the islands of New Zealand; these adaptations may be unique to tuatara since their sphenodontian ancestors lived in the much warmer climates of the Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
.
Species
There are two extant species: Sphenodon punctatus and the much rarer Sphenodon guntheri, or Brothers Island tuatara, which is confined to North Brother IslandThe Brothers, New Zealand
The Brothers is a group of tiny islands in Cook Strait, New Zealand, off the east coast of Arapawa Island.North Brother island in this small chain is a sanctuary for the rare reptile species, the Brothers Island tuatara while the largest of the islands is the site of the Brothers Island...
in Cook Strait
Cook Strait
Cook Strait is the strait between the North and South Islands of New Zealand. It connects the Tasman Sea on the west with the South Pacific Ocean on the east....
. The species name punctatus is Latin for "spotted", and guntheri refers to Albert Günther. S. punctatus was named when only one species was known, and its name is misleading, since both species can have spots. The Brother's Island tuatara (S. guntheri) has olive brown skin with yellowish patches, while the colour of the other species, (S. punctatus), ranges from olive green through grey to dark pink or brick red, often mottled, and always with white spots. In addition, S. guntheri is considerably smaller. A third, extinct species of Sphenodon was identified in November 1885 by William Colenso, who was sent an incomplete sub-fossil specimen from a local coal mine. Colenso named the new species S. diversum. Sphenodon punctatus is further divided into two subspecies: the Cook Strait tuatara (unnamed subspecies), which lives on other islands in and near Cook Strait, and the northern tuatara (Sphenodon punctatus punctatus), which lives on the Bay of Plenty
Bay of Plenty
The Bay of Plenty , often abbreviated to BOP, is a region in the North Island of New Zealand situated around the body of water of the same name...
, and some islands further north. A 2009 paper reexamined the genetic bases used to distinguish the two species of tuatara, and concluded that they only represent geographic variants, and only one species should be recognized.
Description
Amniote
The amniotes are a group of tetrapods that have a terrestrially adapted egg. They include synapsids and sauropsids , as well as their fossil ancestors. Amniote embryos, whether laid as eggs or carried by the female, are protected and aided by several extensive membranes...
; the brain and mode of locomotion resemble that of amphibians and the heart is more primitive than that of any other reptile. Their lungs have a single chamber and lack bronchi.
Both species are sexually dimorphic
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
, males being larger. Adult S. punctatus males measure 61 cm (24 in) in length and females 45 cm (17.7 in). The San Diego Zoo even cites a length of up to 80 cm (31.5 in). Males weigh up to 1 kg (2.2 lb), and females up to 0.5 kg (1.1 lb). Brother's Island tuatara are slightly smaller, weighing up to 660 g (1.3 lb).
The tuatara's greenish brown colour matches its environment, and can change over its lifetime. Tuatara shed their skin at least once per year as adults, and three or four times a year as juveniles. Tuatara sexes differ in more than size. The spiny crest on a tuatara's back, made of triangular soft folds of skin, is larger in males, and can be stiffened for display. The male abdomen is narrower than the female's.
Skull
In the course of evolution, the skull has been modified in most diapsids from the original version evident in the fossil record. However, all the original features are preserved in that of the tuatara; it has two openings (temporal fenestra) on each side of the skull, with complete arches. In addition, the upper jaw is firmly attached to the skull. This makes for a very rigid, inflexible construction. Testudines (turtleTurtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
and tortoise
Tortoise
Tortoises are a family of land-dwelling reptiles of the order of turtles . Like their marine cousins, the sea turtles, tortoises are shielded from predators by a shell. The top part of the shell is the carapace, the underside is the plastron, and the two are connected by the bridge. The tortoise...
) skulls, which lack any temporal fenestra (anapsid condition), are sometimes considered to be the most primitive among amniotes, though there is strong evidence they may have lost the temporal holes rather than never having had them.
The tip of the upper jaw is beak-like and separated from the remainder of the jaw by a notch. There is a single row of teeth in the lower jaw and a double row in the upper, with the bottom row fitting perfectly between the two upper rows when the mouth is closed. This specific tooth arrangement is not seen in any other reptile; although most snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...
s have a double row of teeth in their upper jaw, their arrangement and function is different from the tuatara's. The jaws, joined by ligament
Ligament
In anatomy, the term ligament is used to denote any of three types of structures. Most commonly, it refers to fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.Ligament can also refer to:* Peritoneal...
, chew with backwards and forwards movements combined with a shearing up and down action. The force of the bite is suitable for shearing chitin
Chitin
Chitin n is a long-chain polymer of a N-acetylglucosamine, a derivative of glucose, and is found in many places throughout the natural world...
and bone. The tuatara's teeth are not replaced, since they are not separate structures like real teeth, but sharp projections of the jaw bone. As their teeth wear down, older tuatara have to switch to softer prey such as earthworm
Earthworm
Earthworm is the common name for the largest members of Oligochaeta in the phylum Annelida. In classical systems they were placed in the order Opisthopora, on the basis of the male pores opening posterior to the female pores, even though the internal male segments are anterior to the female...
s, larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e, and slug
Slug
Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...
s, and eventually have to chew their food between smooth jaw bones. The brain of Sphenodon fills only half of the volume of its endocranium
Endocranium
For internal cast of the cranium, see Endocast.The endocranium in comparative anatomy is a part of the skull base in vertebrates and represent the basal, inner part of the cranium. The term is also applied to the outer layer of the dura mater in human anatomy.-Basic structure:Structurally, the...
. This proportion has been used by paleontologists trying to estimate the volume of dinosaur brains based on fossils. The use of tuataras as a model animal for dinosaur brain volume has been criticized because since bird brains occupy a greater portion of their skulls, and dinosaurs are the ancestors of birds, at least some dinosaurs must have had volumes intermediate between the two.
Sensory organs
The eyes can focusAccommodation (eye)
Accommodation is the process by which the vertebrate eye changes optical power to maintain a clear image on an object as its distance changes....
independently, and are specialized with a duplex retina
Duplex retina
A duplex retina is a retina consisting of both rod cells and cone cells. In contrast to duplex retinas, pure rod and pure cone retinas have only rods or cones, respectively....
that contains two types of visual cells for both day and night vision, and a tapetum lucidum
Tapetum lucidum
The tapetum lucidum is a layer of tissue in the eye of many vertebrate animals....
which reflects on to the retina to enhance vision in the dark. There is also a third eyelid on each eye, the nictitating membrane
Nictitating membrane
The nictitating membrane is a transparent or translucent third eyelid present in some animals that can be drawn across the eye for protection and to moisten it while maintaining visibility. Some reptiles, birds, and sharks have a full nictitating membrane; in many mammals, there is a small...
.
The tuatara has a third eye on the top of its head called the parietal eye
Parietal eye
A parietal eye, also known as a parietal organ or third-eye or pineal eye, is a part of the epithalamus present in some animal species...
. It has its own lens, cornea, retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
with rod-like structures, and degenerated nerve connection to the brain, suggesting it evolved from a real eye. The parietal eye is only visible in hatchlings, which have a translucent patch at the top centre of the skull. After four to six months it becomes covered with opaque scales and pigment. Its purpose is unknown, but it may be useful in absorbing ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
rays to manufacture vitamin D
Vitamin D
Vitamin D is a group of fat-soluble secosteroids. In humans, vitamin D is unique both because it functions as a prohormone and because the body can synthesize it when sun exposure is adequate ....
, as well as to determine light/dark cycles, and help with thermoregulation
Thermoregulation
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different...
. Of all extant tetrapods, the parietal eye is most pronounced in the tuatara. The parietal eye is part of the pineal complex, another part of which is the pineal gland
Pineal gland
The pineal gland is a small endocrine gland in the vertebrate brain. It produces the serotonin derivative melatonin, a hormone that affects the modulation of wake/sleep patterns and seasonal functions...
, which in tuatara secretes melatonin at night. It has been shown that some salamanders use their pineal body to perceive polarised light, and thus determine the position of the sun, even under cloud cover, aiding navigation.
Together with turtle
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
s, the tuatara has the most primitive hearing organs among the amniotes. There is no eardrum
Eardrum
The eardrum, or tympanic membrane, is a thin membrane that separates the external ear from the middle ear in humans and other tetrapods. Its function is to transmit sound from the air to the ossicles inside the middle ear. The malleus bone bridges the gap between the eardrum and the other ossicles...
and no earhole, and the middle ear
Middle ear
The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. The mammalian middle ear contains three ossicles, which couple vibration of the eardrum into waves in the fluid and membranes of the inner ear. The hollow space of the middle ear has...
cavity is filled with loose tissue, mostly adipose (fatty) tissue
Adipose tissue
In histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...
. The stapes comes into contact with the quadrate
Quadrate bone
The quadrate bone is part of a skull in most tetrapods, including amphibians, sauropsids , and early synapsids. In these animals it connects to the quadratojugal and squamosal in the skull, and forms part of the jaw joint .- Evolutionary variation :In snakes, the quadrate bone has become elongated...
(which is immovable) as well as the hyoid
Hyoid bone
The hyoid bone is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies at the level of the base of the mandible in the front and the third cervical vertebra behind.Unlike other bones, the hyoid is only distantly...
and squamosal
Squamosal
The squamosal is a bone of the head of higher vertebrates. It is the principal component of the cheek region in the skull, lying below the temporal series and otic notch and bounded anteriorly by postorbital. Posteriorly, the squamosal articulates with the posterior elements of the palatal complex,...
. The hair cell
Hair cell
Hair cells are the sensory receptors of both the auditory system and the vestibular system in all vertebrates. In mammals, the auditory hair cells are located within the organ of Corti on a thin basilar membrane in the cochlea of the inner ear...
s are unspecialized, innervated by both afferent
Afferent nerve
In the nervous system, afferent neurons , carry nerve impulses from receptors or sense organs towards the central nervous system. This term can also be used to describe relative connections between structures. Afferent neurons communicate with specialized interneurons...
and efferent nerve
Efferent nerve
In the nervous system, efferent nerves, otherwise known as motor or effector neurons, carry nerve impulses away from the central nervous system to effectors such as muscles or glands...
fibres, and respond only to low frequencies. Even though the hearing organs are poorly developed and primitive with no visible external ears, they can still show a frequency response from 100–800 Hz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
, with peak sensitivity of 40 dB
Decibel
The decibel is a logarithmic unit that indicates the ratio of a physical quantity relative to a specified or implied reference level. A ratio in decibels is ten times the logarithm to base 10 of the ratio of two power quantities...
at 200 Hz.
Spine and ribs
The tuatara spineVertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
is made up of hourglass-shaped amphicoelous vertebrae, concave both before and behind. This is the usual condition of fish vertebrae and some amphibians, but is unique to tuatara within the amniotes.
The tuatara has gastralia
Gastralium
Gastralia are dermal bones found in the ventral body wall of crocodilian and Sphenodon species. They are found between the sternum and pelvis, and do not articulate with the vertebrae...
, rib-like bones also called gastric or abdominal ribs, the presumed ancestral trait of diapsids. They are found in some lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s, where they are mostly made of cartilage, as well as crocodiles and the tuatara, and are not attached to the spine or thoracic ribs. The true ribs are small projections, with small, hooked bones, called uncinate processes, found on the rear of each rib. This feature is also present in birds. The tuatara is the only living tetrapod
Tetrapod
Tetrapods are vertebrate animals having four limbs. Amphibians, reptiles, birds and mammals are all tetrapods; even snakes and other limbless reptiles and amphibians are tetrapods by descent. The earliest tetrapods evolved from the lobe-finned fishes in the Devonian...
with well-developed gastralia and uncinate processes.
In the early tetrapods, the gastralia and ribs with uncinate processes, together with bony elements such as bony plates in the skin (osteoderms) and clavicle
Clavicle
In human anatomy, the clavicle or collar bone is a long bone of short length that serves as a strut between the scapula and the sternum. It is the only long bone in body that lies horizontally...
s (collar bone), would have formed a sort of exo-skeleton around the body, protecting the belly and helped to hold in the guts and inner organs. These anatomical details most likely evolved from structures involved in locomotion even before the vertebrates ventured onto land. The gastralia may have been involved in the breathing process in early amphibians and reptiles. The pelvis and shoulder girdles are arranged differently to those of lizards, as is the case with other parts of the internal anatomy and its scales.
Tail and back
The spiny plates on the back and tail of the tuatara resemble those of a crocodile more than a lizard, but has the latter reptile's ability to break off its tail when caught by a predator, and then regenerate it. The tail and back are covered with spiny plates that, too, resemble modern crocodiles more than they do those of a lizard.Behaviour
Adult tuatara are terrestrialLandform
A landform or physical feature in the earth sciences and geology sub-fields, comprises a geomorphological unit, and is largely defined by its surface form and location in the landscape, as part of the terrain, and as such, is typically an element of topography...
and nocturnal reptiles, though they will often bask in the sun to warm their bodies. Hatchlings hide under logs and stones, and are diurnal, likely because adults are cannibalistic. Tuatara thrive in temperatures much lower than those tolerated by most reptiles, and hibernate
Hibernation
Hibernation is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and lower metabolic rate. Hibernating animals conserve food, especially during winter when food supplies are limited, tapping energy reserves, body fat, at a slow rate...
during winter. They remain active at temperatures as low as 5 °C (41 °F), while temperatures over 28 °C (82 °F) are generally fatal. The optimal body temperature for the tuatara is from 16 to 21 °C (60.8 to 69.8 F), the lowest of any reptile. The body temperature of tuatara is lower than that of other reptiles ranging from 5.2–11.2 °C (41.4–52.2 F) over a day, whereas most reptiles have body temperatures around 20 °C (68 °F). The low body temperature results in a slower metabolism
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
.
Burrowing seabirds such as petrel
Petrel
Petrels are tube-nosed seabirds in the bird order Procellariiformes. The common name does not indicate relationship beyond that point, as "petrels" occur in three of the four families within that group...
s, prions
Prion (bird)
The Prions are small petrels in the genera Pachyptila and Halobaena. They form one of the four groups within the Procellariidae , along with the gadfly petrels, shearwaters and fulmarine petrels....
, and shearwater
Shearwater
Shearwaters are medium-sized long-winged seabirds. There are more than 30 species of shearwaters, a few larger ones in the genus Calonectris and many smaller species in the genus Puffinus...
s share the tuatara's island habitat during the bird's nesting season. The tuatara use the bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
's burrows for shelter when available, or dig their own. The seabirds' guano
Guano
Guano is the excrement of seabirds, cave dwelling bats, and seals. Guano manure is an effective fertilizer due to its high levels of phosphorus and nitrogen and also its lack of odor. It was an important source of nitrates for gunpowder...
helps to maintain invertebrate populations that tuatara predominantly prey on; including beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s, cricket
Cricket
Cricket is a bat-and-ball game played between two teams of 11 players on an oval-shaped field, at the centre of which is a rectangular 22-yard long pitch. One team bats, trying to score as many runs as possible while the other team bowls and fields, trying to dismiss the batsmen and thus limit the...
s, and spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
s. Their diet also consists of frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
s, lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s, and bird's eggs and chicks. The eggs and young of seabirds that are seasonally available as food for tuatara may provide beneficial fatty acids
Essential fatty acid
Essential fatty acids, or EFAs, are fatty acids that humans and other animals must ingest because the body requires them for good health but cannot synthesize them...
. Tuatara of both sexes defend territories, and will threaten and eventually bite intruders. The bite can cause serious injury. Tuatara will bite when approached, and will not let go easily.
Reproduction
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
s once every four years. During courtship, a male makes his skin darker, raises his crests, and parades toward the female. He slowly walks in circles around the female with stiffened legs. The female will either submit, and allow the male to mount her, or retreat to her burrow. Males do not have a penis
Penis
The penis is a biological feature of male animals including both vertebrates and invertebrates...
; they reproduce by the male lifting the tail of the female and placing his vent
Cloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...
over hers. The sperm
Sperm
The term sperm is derived from the Greek word sperma and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell...
is then transferred into the female, much like the mating process in birds.
Invercargill
Invercargill is the southernmost and westernmost city in New Zealand, and one of the southernmost cities in the world. It is the commercial centre of the Southland region. It lies in the heart of the wide expanse of the Southland Plains on the Oreti or New River some 18 km north of Bluff,...
, New Zealand, became a father (possibly for the first time) on 23 January 2009.
The sex of a hatchling depends on the temperature
Temperature-dependent sex determination
Temperature-dependent sex determination is type of environmental sex determination in which the temperatures experienced during embryonic development determine the sex of the offspring. It is most prevalent and common among amniote vertebrates that are classified under the reptile class, but is...
of the egg, with warmer eggs tending to produce male tuatara, and cooler eggs producing females. Eggs incubated at 21 °C (70 °F) have an equal chance of being male or female. However, at 22 °C (72 °F), 80% are likely to be males, and at 20 °C (68 °F), 80% are likely to be females; at 18 °C (64 °F) all hatchlings will be females. There is some evidence that sex determination in tuatara is determined by both genetic and environmental factors.
Tuatara probably have the slowest growth rates of any reptile, continuing to grow larger for the first 35 years of their lives. The average lifespan is about 60 years, but they can live to be well over 100 years old. Some experts believe that captive tuatara could live as long as 200 years.
Conservation
Distribution and threats
Tuatara were long confined to 32 offshore islands free of mammals. The islands are difficult to get to, and are colonised by few animal species, indicating that some animals absent from these islands may have caused tuatara to disappear from the mainland. However, kiore (Polynesian ratPolynesian Rat
The Polynesian Rat, or Pacific Rat , known to the Māori as kiore, is the third most widespread species of rat in the world behind the Brown Rat and Black Rat. The Polynesian Rat originates in Southeast Asia but, like its cousins, has become well travelled – infiltrating Fiji and most Polynesian...
s) had recently established on several of the islands, and tuatara were persisting, but not breeding, on these islands. Additionally, tuatara were much rarer on the rat-inhabited islands.
The recent discovery of a tuatara hatchling on the New Zealand mainland indicates that attempts to reestablish a breeding population on the mainland have had some success. The total population of tuatara of all species and subspecies is estimated to be greater than 60,000, but less than 100,000.
Eradication of rats
Tuatara were removed from Stanley, Red Mercury and Cuvier IslandCuvier Island
Cuvier Island is a small island off the east coast of the North Island of New Zealand. It lies on the seaward end of the Colville Channel, north of the Mercury Islands and approximately south-east of Great Barrier Island...
s in 1990 and 1991, and maintained in captivity to allow Polynesian rats to be eradicated on those islands. All three populations bred in captivity, and after successful eradication of the rats, all individuals including the new juveniles were returned to their islands of origin. In the 1991–92 season, Little Barrier Island was found to hold only eight tuatara, which were taken into in situ captivity, where females produced 42 eggs, which were incubated at Victoria University. The resulting offspring were subsequently held in an enclosure on the island, then released into the wild in 2006 after rats were eradicated there.
In the Hen and Chicken Islands
Hen and Chicken Islands
The Hen and Chickens Islands lie to the east of the North Auckland Peninsula off the coast of northern New Zealand. They are located to the east of Bream Head and southeast of Whangarei....
, Pacific rats were eradicated on Whatupuke in 1993, Lady Alice Island in 1994, and Coppermine Island in 1997. Following this program, juveniles have once again been seen on the latter three islands. In contrast, rats persist on Hen Island of the same group, and no juvenile tuatara had been seen there as of 2001. In the Alderman Islands
Alderman Islands
The Aldermen Islands are a small group of rocky islets to the southeast of Mercury Bay in the North Island of New Zealand. They are located off the coast of the Coromandel Peninsula, east of the mouth of the Tairua River....
, Middle Chain Island holds no tuatara, but it is considered possible for rats to swim between Middle Chain and other islands that do hold tuatara, and the rats were eradicated in 1992 to prevent this. Another rodent eradication was carried out on the Rangitoto Islands east of D’Urville Island, to prepare for the release of 432 Cook Strait tuatara juveniles in 2004, which were being raised at Victoria University as of 2001.
Brothers Island tuatara
Sphenodon guntheri is present naturally on one small island with a population of approximately 400. In 1995, 50 juvenile and 18 adult Brothers Island tuatara were moved to Titi Island in Cook Strait, and their establishment monitored. Two years later, more than half of the animals had been re-sighted and all but one had gained weight. In 1998, 34 juveniles from captive breeding and 20 wild caught adults were similarly transferred to Matiu/Somes IslandMatiu/Somes Island
Matiu/Somes Island, at , is the largest of three islands in the northern half of Wellington Harbour, New Zealand. It lies south of the suburb of Petone and the mouth of the Hutt River, and about northwest of the much smaller Makaro/Ward Island....
, a more publicly accessible location within Wellington Harbour. The captive juveniles were from induced layings from wild females.
In late October 2007, it was announced that 50 tuatara collected as eggs from North Brother Island and hatched at Victoria University were being released onto Long Island in the outer Marlborough Sounds
Marlborough Sounds
The Marlborough Sounds are an extensive network of sea-drowned valleys created by a combination of land subsidence and rising sea levels at the north of the South Island of New Zealand...
. The animals had been cared for at Wellington Zoo for the last five years and have been kept in secret in a specially built enclosure at the zoo, off display.
Northern tuatara
Sphenodon punctatus naturally occurs on 29 islands and its population is estimated to be over 60,000 individuals. In 1996, 32 adult northern tuatara were moved from Moutoki Island to Moutohora. The carrying capacity of Moutohora is estimated at 8500 individuals, and the island could allow public viewing of wild tuatara. In 2003, sixty northern tuatara were introduced to Tiritiri Matangi IslandTiritiri Matangi Island
Tiritiri Matangi Island lies in the Hauraki Gulf of New Zealand, east of the Whangaparaoa Peninsula in the North Island and north east of Auckland. The island is an open nature reserve managed under the supervision of the Department of Conservation and is noted for its bird life, including kiwi...
from Middle Island in the Mercury group
Mercury Islands
The Mercury Islands lie off the northeast coast of New Zealand's North Island. They are located off the coast of the Coromandel Peninsula, and northeast of the town of Whitianga....
. They are occasionally seen sunbathing by visitors to the island.
A mainland release of S. punctatus occurred in 2005 in the heavily fenced and monitored Karori Sanctuary
Karori Wildlife Sanctuary
Zealandia, formerly known as the Karori Wildlife Sanctuary, is a protected natural area in Wellington, New Zealand, where the biodiversity of 225 ha of forest is being restored...
. The second mainland release took place in October 2007, when a further 130 were transferred from Stephens Island
Stephens Island, New Zealand
Stephens Island is at the northern most tip of the Marlborough Sounds in the South Island of New Zealand. It lies two kilometres to the northeast of Cape Stephens, the northernmost point of D'Urville Island. The Māori call the island Takapourewa but Stephens Island is the commonly used name...
to the Karori Sanctuary. In early 2009 the first recorded wild-born offspring were observed.
Captive breeding
There are several tuatara breeding programmes within New Zealand. Southland Museum and Art GallerySouthland museum and art gallery
The Southland Museum and Art Gallery is located in Gala Street, Invercargill, New Zealand. It is Southland's largest cultural and heritage institution, and contains a wide variety of the region's art, history and natural history collections.-Observatory:...
in Invercargill
Invercargill
Invercargill is the southernmost and westernmost city in New Zealand, and one of the southernmost cities in the world. It is the commercial centre of the Southland region. It lies in the heart of the wide expanse of the Southland Plains on the Oreti or New River some 18 km north of Bluff,...
, was the first to have a tuatara breeding programme; they breed Sphenodon punctatus. Hamilton Zoo
Hamilton Zoo
Hamilton Zoo is the main zoological garden of Hamilton, New Zealand. It is situated on Brymer Road in the Hamilton suburb of Rotokauri, on the outskirts of the metropolitan area towards the northwest...
, Auckland Zoo
Auckland Zoo
Auckland Zoo is a zoological garden in Auckland, New Zealand, situated next to Western Springs park not far from Auckland's central business district. It is run by the Auckland City Council with the Auckland Zoological Society as a supporting organisation....
and Wellington Zoo
Wellington Zoo
Wellington Zoo is nestled in the green belt of Wellington, New Zealand. Now over 100 years old, it was the country’s first Zoo and has dedicated to over 100 different species of fauna from across the globe...
also breed tuatara for release into the wild. The Victoria University of Wellington
Victoria University of Wellington
Victoria University of Wellington was established in 1897 by Act of Parliament, and was a former constituent college of the University of New Zealand. It is particularly well known for its programmes in law, the humanities, and some scientific disciplines, but offers a broad range of other courses...
maintains a research programme into the captive breeding of tuatara, and the Pukaha Mount Bruce Wildlife Centre
Mt Bruce Wildlife Centre
Pukaha Mount Bruce Wildlife Centre is a wildlife restoration organisation based around a protected forest area in New Zealand's Wairarapa district.-History:...
keeps a pair and a juvenile. The WildNZ Trust has a tuatara breeding enclosure at Ruawai
Ruawai
Ruawai is a small township located 30 km south of Dargaville in Northland, New Zealand. The population was 426 in the 2006 Census, a decrease of 30 from 2001....
. On 28 January 2009, the 11th of 11 eggs belonging to tuataras Henry and Mildred hatched. This rare occurrence came after Henry had surgery to remove a cancerous tumor that was inhibiting both his ability and desire to breed.
Cultural significance
Tuatara feature in a number of indigenous legends, and are held as ariki (God forms). Tuatara are regarded as the messengers of WhiroWhiro
In Māori mythology, Whiro is the lord of darkness, or the embodiment of all evil. He inhabits the underworld and is responsible for the ills of all persons....
, the god
Deity
A deity is a recognized preternatural or supernatural immortal being, who may be thought of as holy, divine, or sacred, held in high regard, and respected by believers....
of death and disaster, and Māori women are forbidden to eat them. Tuatara also indicate tapu (the borders of what is sacred and restricted), beyond which there is mana, meaning there could be serious consequences if that boundary is crossed. Māori women would sometimes tattoo images of lizards, some of which may represent tuatara, near their genitals. Today, tuatara are regarded as a taonga
Taonga
A taonga in Māori culture is a treasured thing, whether tangible or intangible. Tangible examples are all sorts of heirlooms and artefacts, land, fisheries, natural resources such as geothermal springs and access to natural resources, such as riparian water rights and access to the riparian zone of...
(special treasure).
The tuatara was featured on one side of the New Zealand 5 cent coin, which was phased out in October 2006. Tuatara was also the name of the Journal of the Biological Society of Victoria University College and subsequently Victoria University of Wellington
Victoria University of Wellington
Victoria University of Wellington was established in 1897 by Act of Parliament, and was a former constituent college of the University of New Zealand. It is particularly well known for its programmes in law, the humanities, and some scientific disciplines, but offers a broad range of other courses...
, published from 1947 until 1993. It has now been digitised by the New Zealand Electronic Text Centre
New Zealand Electronic Text Centre
The New Zealand Electronic Text Centre is a unit of the library at the Victoria University of Wellington which provides a free online archive of New Zealand and Pacific Islands texts and heritage materials. The NZETC has an ongoing programme of digitisation and feature additions to the current...
, also at Victoria.
External links
- Tuatara in Te Ara – the Encyclopedia of New Zealand
- Specimens of Tuatara in the collection of the Museum of New Zealand Te Papa Tongarewa
Institutions that keep live tuatara
New Zealand- Auckland Zoo
- Hamilton Zoo Tuatara breeding
- Natureland Zoo, Nelson, NZ
- Pukaha Mount Bruce
- Kiwi Birdlife Park Queenstown
- Southland Museum and Art Gallery
- Victoria University of Wellington
- Wellington Zoo
- WildNZ Trust Projects at Ruawai
Australia
Europe
United States
- Dallas Zoo
- Saint Louis Zoo
- San Diego Zoo (S. guntheri)
- Toledo Zoo