Tuatara

The tuatara (/tuːəˈtɑːrə/, Māori: [ˈtʉ.a.ta.ɾa]; Sphenodon punctatus) is a species of reptile endemic to New Zealand. Though it looks like a lizard, it is the only living member of a unique group called the order Rhynchocephalia. This special animal has a spiky crest along its back and teeth on the roof of its mouth.

Tuatara first appeared millions of years ago during the Mesozoic era and were once found all over the world. Today, they survive only in a few places, mainly on small islands off the coast of New Zealand. They are important for scientists who study how animals change over time.

Tuatara are protected by law because they face threats from losing their homes and from animals like the Polynesian rat (Rattus exulans). In 2005, tuatara were reintroduced to the mainland at the Karori Wildlife Sanctuary (now named "Zealandia"), marking an important step in helping this unique species recover.

Taxonomy and evolution

The tuatara belongs to a special group of reptiles called Rhynchocephalia. Although it looks like a lizard, it is actually the only living member of this group. Scientists first thought tuatara were lizards, but later discovered they have features similar to birds, turtles, and crocodiles. Because of this, they gave tuatara their own group name.

Tuatara have lived on Earth for millions of years. Their ancient relatives were small reptiles that lived long ago during the time of dinosaurs. Today, tuatara are found only in New Zealand. There is just one species of tuatara, but there are two different types based on where they live. One type has olive brown skin with yellowish patches, while the other can be olive green, grey, pink, or brick red with white spots.

Description

Tuatara are the largest reptiles in New Zealand. Adult males can be up to 80 cm long, while females are smaller. They have a spiny crest on their back, which is larger in males. Tuatara change color over their lifetime and shed their skin yearly.

Unlike most lizards, tuatara have a complete bar closing the lower part of the skull behind the eye. They also have unique teeth that are fused to their jawbone and do not grow replaced. Tuatara can see well in both day and night and have a special third eye on top of their head that helps them sense light changes.

Tuatara break off their tails when threatened and can regrow them, though it takes a long time. They are active at lower temperatures than most reptiles and can stay active in chilly weather.

Ecology

Tuatara share their island homes with burrowing seabirds like petrels, prions, and shearwaters. These birds create burrows that tuatara use for shelter, and their guano helps keep many insects alive, which tuatara eat. Tuatara mainly eat beetles, crickets, spiders, wētās, earthworms, and snails, but they also eat frogs, lizards, and sometimes bird eggs and chicks.

Both male and female tuatara defend their areas and will bite intruders if they get too close. They do not let go easily when they bite. Female tuatara sometimes stay close to their nests to protect them. Tuatara can also be affected by a special kind of tick called the tuatara tick.

Reproduction

Tuatara reproduce very slowly, taking 10 to 20 years to reach sexual maturity. During courtship, a male makes his skin darker and parades toward the female. The female may allow the male to mount her or retreat to her burrow. Adult males do not have a penis; instead, they transfer sperm by placing their vent over the female's in a process called a "cloacal kiss".

Tuatara eggs have a soft shell and take between 12 and 15 months to hatch after copulation. The sex of a hatchling depends on the temperature of the egg, with warmer temperatures producing more males and cooler temperatures producing more females. Tuatara can live for over 100 years, possibly due to genes that protect against damage from oxygen.

Genomic characteristics

The tuatara has a very large genome, the second largest known among reptiles. Researchers have found many types of genetic elements in its DNA, including over 8,000 non-coding RNA-related elements and around 7,500 LTRs. The tuatara also has 56 genes related to the major histocompatibility complex, which help with disease resistance and recognizing relatives.

The mitochondrial genome of the tuatara is about 18,000 base pairs long and contains genes for proteins, ribosomal RNA, and transfer RNA. Studies show that a high percentage of CpG sites in the tuatara genome are methylated, similar to patterns seen in zebrafish but higher than in humans. These findings suggest that the tuatara’s genome has unique features compared to other animals.

Main article: major histocompatibility complex
Main articles: lepidosaur , Sauropsida

Conservation

Tuatara are protected by New Zealand's Wildlife Act 1953 and are listed under the Convention on International Trade in Endangered Species, which stops people from trading them freely.

Tuatara used to live all over New Zealand, but they disappeared from the main islands long ago. Today, they live on 32 islands without mammals, where they are safe. Scientists are working hard to help tuatara live on the mainland again. There are between 60,000 and 100,000 tuatara left.

Scientists are also worried about climate change because the temperature when tuatara eggs hatch decides if the baby will be male or female. Warmer temperatures might mean fewer female tuatara, so scientists are finding ways to keep the balance.

In many places, people have removed rats and other animals that eat tuatara eggs. This has helped tuatara populations grow again. Some tuatara have even been moved to new islands or zoos to help them survive.

Cultural significance

Tuatara have an important place in Māori legends and traditions. They are seen as messengers of Whiro, the god of death and disaster, and are considered sacred. Because of this, Māori women were not allowed to eat them. Tuatara are also viewed as guardians of knowledge and special treasures.

In the past, the tuatara appeared on one side of the New Zealand five-cent coin before it was phased out in 2006. The name "Tuatara" was also used for a journal published by Victoria University of Wellington from 1947 until 1993.