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Pāua
Exploring Haliotis iris, New Zealand's iconic marine gastropod
What is Pāua?
Pāua (Haliotis iris) are a species of large marine gastropod endemic to Aotearoa New Zealand. They typically grow up to 150 millimetres in shell length, though individuals in favourable conditions can exceed 180 millimetres. Their shells are thick, oval, and heavily ridged, with a distinctive row of respiratory holes along one side. The exterior is usually dark and rough, blending into rocky reefs, while the interior is famous for its iridescent blue-green pāua shell used widely in jewellery and carving.
Summary of video
  • Abalone are marine snails (gastropods), not bivalves; they have one flat shell with small holes for water flow.
  • They move using a large muscular foot that sticks strongly to surfaces and is the main edible part.
  • On the head they have eyes, antennae, and a mouth, which contains a radula—a toothed, scraping tongue used to eat algae.
  • Inside, abalone have gills for breathing, a shell muscle that attaches them to the shell, and an anus located near the head.
  • The gonads (green in females, beige in males) sit around the liver, and the heart is transparent and visibly beating during dissection.
  • The video shows how to remove the shell, identify organs, and explains how the shell holes help with respiration, waste removal, and releasing eggs/sperm.
Habitat and Distribution
Pāua inhabit cold, temperate coastal waters around New Zealand, especially along exposed rocky shorelines. They are most abundant in shallow subtidal zones, from just below the low-tide mark down to about 10 metres deep, where wave action brings a steady supply of nutrients. Pāua prefer hard substrates—rock outcrops, boulder fields, and kelp-covered reefs—where they can cling tightly using a powerful muscular foot.
Life Cycle
The life cycle of Haliotis iris begins when adults release eggs and sperm directly into the water column during spawning events, typically in autumn and early winter. Fertilised eggs hatch into free-swimming larvae that drift as plankton for about one to two weeks. When ready to settle, larvae attach to hard surfaces covered in coralline algae, then transform into juvenile pāua. These juveniles graze on microscopic algae until they grow large enough to feed on larger seaweeds such as kelp.
Morphology and Adaptations
Shell Structure
Their flattened, sturdy shells help them withstand strong waves, and their muscular foot allows them to anchor firmly to rocks.
Iridescent Nacre
The iridescent inner shell is produced by layers of nacre, giving pāua one of the most striking natural colourations of any marine species.
Feeding Behaviour
Their diet consists mainly of brown and red macroalgae, making them important grazers that help regulate algal growth on rocky reefs.
Morphologically, pāua are well adapted to life on exposed coasts.
Ecological Importance
Ecologically, pāua play a significant role in New Zealand's coastal ecosystems. By grazing on kelp and seaweed, they help maintain balanced reef communities and support biodiversity. They also serve as prey for species such as crayfish, octopus, and fish. Their presence is often an indicator of healthy, well-oxygenated, unpolluted coastal waters with intact kelp forests.
Threats to Pāua Populations
Despite this, pāua populations face a number of threats.
Overfishing
Both legal and illegal fishing has placed pressure on many local stocks, particularly in areas easily accessible from shore.
Habitat Degradation
Sedimentation, pollution, and coastal development can reduce the availability of suitable rocky habitat.
Climate Change
Storm events and marine heatwaves, exacerbated by climate change, threaten kelp forests that pāua depend on for food.
Predator Imbalance
Predators such as kina (sea urchins) can reshape reef environments when their numbers increase due to declining predator species.
Conclusion
In conclusion, Haliotis iris is an iconic and ecologically important species in New Zealand's coastal ecosystems. Their unique biology, striking shell, and cultural significance highlight the need for careful management, sustainable harvesting, and protection of the rocky reef habitats that support pāua populations throughout Aotearoa.