sits on the surface of the sand

Size
Shell: 5–8 cm, Weight: 30–60 g
Lifespan
20–30 years
Diet
Phytoplankton and organic particles. Filters food from the water using its gills. Draws water in through its siphon and extracts microscopic algae. Feeds continuously when submerged.
Habitat
Sandy bottoms in sheltered bays, harbours and estuaries from the low tide mark down to 20 metres depth. Lives on the surface of the sand rather than burrowing. Often found in large aggregations.
Range
Coastal waters of the North and South Islands from Northland to Otago. Most common in sandy bays and harbours. Also found in southern Australia and Tasmania.
Endemism
Native
Main Threats
Recreational harvesting in some areas. Habitat loss from coastal development and dredging. Climate change affecting estuarine habitats. Often collected by beachgoers for its attractive, strongly ribbed shell.
Population
Populations are considered stable across most of the species' range. The dog cockle is not commercially harvested in New Zealand but is sometimes collected by recreational gatherers for its meat. It is more commonly collected for its attractive shell.
Conservation Status
Not Threatened
Human Risk
harmless
Handling Note
common intertidal cockle, safe to handle
Conservation Note
Native mollusc; common on sandy beaches and not subject to conservation assessment.
Te Ao Māori
In Māori tradition, Kuhakuha was a shellfish of the sandy bays. Its strong, ribbed shell was used as a scraper and as a tool for working wood. The meat was eaten but was considered less tasty than the common cockle. The name refers to the puffing sound the shellfish makes when it expels water. It was a familiar resident of the intertidal zone, gathered by families during low tide excursions.
It does not burrow. Named for its large size and its strong, dog-like teeth along the hinge of its shell. A cockle that lives in the open. Its shell is covered in strong, radiating ribs that make it stand out from the smooth-shelled pipi and tuatua. Unlike the common cockle (tuangi), the dog cockle does not burrow into the sand. It lives on the surface, often in large beds visible at low tide. This surface-dwelling habit makes it more vulnerable to predators and to human harvesters. The dog cockle's ribs are not just decorative. They strengthen the shell, allowing it to resist the crushing attacks of crabs and starfish. The shell is thick and heavy for its size, a sturdy fortress against the dangers of the intertidal zone. When the tide goes out, the dog cockle closes its shell tightly, trapping a small amount of water inside to keep its gills moist until the tide returns. The Māori name Kuhakuha means to cough or puff, possibly referring to the way the shell opens and closes. When a dog cockle is exposed at low tide, it will sometimes snap its shell shut, expelling a jet of water. That puffing sound, repeated across a bed of thousands of cockles, creates a soft chorus on the quiet beach. Its strong, ribbed shell has been used as a tool and as a decoration. The radiating ribs make it easy to grip, and the shell is strong enough to use as a scraper for working wood or cleaning fish. Today, it is more commonly collected by beachcombers who admire its architectural beauty. The low tide beach is quiet. The dog cockle lies on the sand, ribbed shell thick and heavy. A crab approaches. The cockle snaps shut. The crab gives up. The cockle does not know it is a fortress. It does not know its ribs are weapons. It just wants to filter water. A clean dog cockle shell, bleached white by the sun, is a prize find on any sandy beach. The ribs catch the light, casting shadows that emphasise the shell's elegant geometry. The dog cockle is proof.