wears its lunch as a coat
- Size
- Carapace: 5–8 cm, Leg span: 15–20 cm
- Lifespan
- 3–5 years
- Diet
- Herbivorous and detritivorous. Grazes on algae films and dead plant matter.
- Habitat
- Intertidal and shallow subtidal rocky shores. Needs pools and crevices.
- Range
- Throughout New Zealand. Common on rocky shores from north to south.
- Endemism
- Endemic
- Main Threats
- Predation by birds and fish. Low threat from pollution or disturbance.
- Population
- Abundant in coastal areas. Resilient generalist with wide tolerance.
- Conservation Status
- data_deficient
- Human Risk
- caution
- Handling Note
- dense setae and spines can irritate skin if handled
- Conservation Note
- Marine crustacean outside the scope of current NZTCS terrestrial and freshwater assessments.
- Te Ao Māori
- The Hairy seaweed crab is a familiar sight to beachcombers. Its ability to decorate itself with seaweed is a classic example of active camouflage. In Māori tradition, crabs were a food source, and this species would have been gathered alongside others.
It vanishes in summer. Not literally. But the heat dries the rock pools. The Hairy seaweed crab retreats to damp crevices. It waits for the tide. Its body is covered in dense setae. These hairs hold water and debris. It is a walking sponge.
Found throughout New Zealand. It is one of the most common crabs on rocky shores. From north to south, it is present. It tolerates wide temperature ranges. It is a generalist.
Threats are low. It is resilient to pollution and disturbance. Predation by birds and fish is high. The crab relies on camouflage. It holds seaweed in its claws. It blends in. It survives.
Habitat is rocky intertidal. It needs pools and crevices. Flat rock is exposed. The crab seeks complexity. It finds it in the surge zone. The water crashes. The crab holds on.
Diet is algae and detritus. It grazes on the film of green algae on rocks. It eats dead plant matter. It is a cleaner. It keeps the rocks tidy. It is essential.