For many humans seeking enlightenment, or a higher form of self-being, the third eye serves as a representation of the internal chamber, or pineal gland, that bridges a gap between the plane we inhabit and other unknown planes existing among us (McGovern, 2007). In the case of a certain reptile, however, interpretations about the role of the third eye rely purely on anatomical physiology. The tuatara (Sphenodon punctatus) is a member of the order Rhynchocephalia, and the last of its evolutionary line. Sometimes these animals are referred to as lizards, though this is not quite a correct assessment. These organisms are more pseudo-lizards, as phyletically (or organizationally to other organisms) tuatara comprise of their own independent clade and traditional lizards are within a separate order, Squamata; see Figure 1.
In addition to being the last living representatives of Rhynchocephalia, tuatara are the oldest known living reptiles–even predating the emergence of dinosaurs (Helicon, 2018; Gemmell et al., 2020). These reptiles are thought to have been first named by the Māori tribe, an indigenous group of peoples whom inhabited regions of New Zealand around 700 years ago. To local tribes, tuatara were thought to be embodiments of guardians that would protect sacred locations (Gemmell et al., 2020).
Tuatara can be found on 30 small islands in New Zealand (Helicon, 2018), however population trends as of recent are unknown and more research into organism abundance and habitat quality assessments are needed. These reptiles can live up to 60 years under proper conditions, 20 years more than the longest-known living lizard the Komodo dragon (Smithsonian’s NZCBI). Perhaps having direct access for the world through the pineal gland or ‘third eye’ has a role to play in maintaining such an elongated lifespan.
Environmental access to the pineal gland is on top of the tuatara’s head medial to the eyes, but placement is closer toward the spine than the nostril region (see the photo on the right). Researchers deemed this access point to the gland ‘the third eye’, as this small opening in fact contains a functioning and innervated retina! The third eye plays such a crucial role in organismal function that it has remained evolutionarily (genetically) unchanged for roughly 220 million years (Helicon, 2018). As for the specific purpose, this access point to the pineal gland is believed to serve as a regulator for sun exposure. As an ectotherm, tuatara rely primarily on environmental temperatures to alter internal body temperatures. The third eye contributes to behavioral regulation for optimal sun exposure, helping to maintain the body at an ideal level of heat (Stebbins, 1958).
Though not spiritual in nature, the fundamental understandings we have on the third eye of the tuatara has fueled evolutionary research–specifically in regard to amniote divergence on the geologic time scale (Gemmell et al., 2020).
If you are interested in learning more about this species, Discovery UK has a wonderful educational video on the subject, accessible below.
Gemmell, N. J., K. Rutherford, S. Prost, et al.. 2020. “The tuatara genome reveals ancient features of amniote evolution.” Nature, 584: 403-409.
Helicon. 2018. “Tuatara.” The Hutchinson unabridged encyclopedia with atlas and weather guide.
McGovern, U.. 2007. “Third eye.” Chambers Dictionary of the unexplained. ISBN: 978-0-550-10215-7
Stebbins, R. C.. 1958. “An experimental study of the ‘third eye’ of the tuatara.” Copeia, 3: 183-190. DOI: 10.2307/1440585