Sphenodon, commonly known as tuatara, is a genus of reptiles belonging to the family Sphenodontidae. This genus comprises two species, Sphenodon punctatus and Sphenodon guntheri, and is endemic to New Zealand. Tuatara are considered a living fossil, as they are the only extant members of the order Rhynchocephalia and have remained relatively unchanged for over 200 million years.
The term "sphenodon" is derived from the Greek words "sphen," meaning "wedge," and "odon," meaning "tooth." This refers to the distinctive dental arrangement present in tuatara, where the upper jaw features two rows of teeth fitting neatly between the single row of teeth in the lower jaw.
The tuatara is characterized by a unique combination of reptilian and lizard-like features. It has a spiny crest along its back, prominent vertical pupils, and a third, "parietal," eye located on the top of its head. The parietal eye, although structurally similar to the other two eyes, lacks a lens and is involved in regulating circadian rhythms.
These creatures have a slow rate of growth and extended lifespan, with some individuals living up to 100 years or even more. They are primarily nocturnal and feed on various invertebrates, small vertebrates, and bird eggs. Tuatara also possess a specialized cloacal gland that secretes a unique scent, used for communication and territorial marking.
Due to habitat loss and the introduction of predators, tuatara populations have declined significantly, and both species are now classified as threatened. Conservation efforts aim to protect their unique evolutionary lineage and ensure their survival for future generations.
