Paua shells are the iridescent shells of a marine snail found predominantly in New Zealand waters. Valued for their unique visual properties, these captivating shells have become a symbol of New Zealand’s natural heritage and a sought-after material for artistic and decorative applications.
The Paua and Its Origin
Paua is the Māori name for several species of large, edible sea snails, a type of abalone. Haliotis iris, also known as blackfoot paua or rainbow abalone, is the most well-known and commercially harvested species, endemic to New Zealand’s coastal waters.
Paua inhabit shallow, cool coastal areas along rocky shorelines, typically at depths of 1 to 15 meters. They use a large, muscular foot to cling firmly to rocks, allowing them to withstand strong tidal surges. Their diet primarily consists of seaweed and algae, which they graze from rock surfaces or capture as drift seaweed.
Distinctive Features of the Shell
The paua shell is distinctive for its brilliant iridescence, displaying a spectrum of colors including deep blues, greens, purples, and pinks, with occasional yellow or golden reflections. This vibrant appearance is due to the inner layer of the shell, known as nacre or mother-of-pearl. Nacre is an organic-inorganic composite material primarily composed of microscopic, hexagonal platelets of aragonite, a form of calcium carbonate.
These aragonite platelets are arranged in continuous parallel layers, separated by thin sheets of organic matrix. The iridescence arises because the thickness of these aragonite platelets is similar to the wavelength of visible light. Light interacts with these layered structures through a phenomenon called Bragg diffraction, causing different wavelengths to constructively and destructively interfere at various viewing angles, thereby creating the shifting colors. The shell’s exterior is typically rough, dull, and often encrusted with marine organisms, which provides camouflage, contrasting sharply with its smooth, vibrant interior.
Cultural Significance and Applications
Paua shells hold profound cultural importance for the Māori people of New Zealand, who consider them a “taonga” or treasure. They are traditionally used in various art forms, including as the iridescent eye inlays for carved wooden figures and as decorative elements on traditional garments and jewelry. The shells are also valued for their spiritual significance, sometimes associated with the stars or ancestral eyes.
In modern times, paua shells continue to be popular for contemporary jewelry, decorative crafts, and souvenirs. New Zealand has implemented regulations to ensure the sustainable harvesting of paua populations. These measures include strict quotas, minimum legal sizes for harvested shells, and requirements for divers to free-dive without the use of underwater breathing apparatus.