The tuatara is a reptile native exclusively to New Zealand, representing the sole surviving member of the ancient order Rhynchocephalia. Its lineage diverged from lizards and snakes roughly 240 million years ago, earning it the nickname “living fossil.” The tuatara is a slow-moving, opportunistic carnivore whose diet is broadly classified as faunivorous, meaning it consumes animal matter. Its extremely slow metabolism directly influences its feeding habits and consumption rate.
Primary Invertebrate Prey
The staple diet of the adult tuatara consists predominantly of terrestrial invertebrates, which they hunt primarily under the cover of night. Their nocturnal activity coincides with the emergence of many prey species, allowing the tuatara to ambush victims. Their slow metabolism enables them to remain active at temperatures as low as 45 degrees Fahrenheit, resulting in infrequent feeding compared to other cold-blooded animals.
The primary food sources include a wide variety of arthropods with tough exoskeletons, such as beetles, spiders, earthworms, and native wētā. A unique dental arrangement facilitates the consumption of rigid prey: a single row of teeth on the lower jaw slots between two rows on the upper jaw. This specialized dentition allows the tuatara to shear and crush the hard casings of insects effectively before swallowing.
Opportunistic and Vertebrate Consumption
The tuatara is a versatile and opportunistic predator that consumes larger vertebrate prey when available. This behavior is most pronounced on the offshore islands it inhabits, many of which host large colonies of burrowing seabirds like petrels and prions. Tuatara often cohabitate in the burrows dug by these birds, which provides both shelter and a seasonal, high-protein food source.
During the summer breeding season, tuatara consume seabird eggs and newly hatched chicks, such as those of the fairy prion. This seasonal shift provides a substantial boost of calories when the reptile’s metabolic demands are highest. They also prey upon smaller reptiles, including geckos and skinks, cementing their role as an apex predator in their restricted island ecosystem. Adult tuatara have also been known to engage in cannibalism, occasionally preying upon smaller members of their own species.
Dietary Shifts Based on Age and Environment
The tuatara’s diet changes significantly throughout its life. Juvenile tuatara, particularly post-hatchlings, focus on smaller, softer-bodied invertebrates compared to adults. These young reptiles are also more active during the day, a behavioral adaptation that serves as a defense mechanism against the cannibalistic tendencies of nocturnal adults.
Environmental factors strongly dictate the availability and composition of the tuatara diet. The rich soil fertility provided by seabird guano supports a higher density of invertebrates, which sustains the tuatara population. The presence of seabirds is a seasonal factor that allows for the consumption of larger prey like chicks and eggs, which would otherwise be scarce. This ability to exploit both invertebrate and seasonal vertebrate opportunities showcases the tuatara’s adaptability within its isolated ecological niche.