laces up the shaded vertical rock faces

Size
Height: 10–20 cm
Lifespan
2–5 years
Diet
Photosynthetic. Draws energy from sunlight and nutrients from surrounding water. Requires clean water and good flow.
Habitat
Clear, sheltered rocky reefs in low intertidal and shallow subtidal zones, often on vertical rock faces and under overhangs where light filters through.
Range
Found throughout the North and South Islands on rocky reefs in low intertidal and shallow subtidal zones of clear, sheltered waters. Also found in Australia and South America.
Endemism
Native
Main Threats
None significant. Localised threats include coastal development, pollution, sedimentation from land clearance, and climate change affecting water temperature and clarity.
Population
Not Threatened. Common on rocky reefs throughout New Zealand, particularly in clear, sheltered waters. Often grows on vertical rock faces and under overhangs.
Conservation Status
Not Threatened
Human Risk
harmless
Handling Note
marine algae, safe to handle
Conservation Note
Native red algae; not assessed by NZTCS as marine algae are outside the scope of current threat classifications.
Te Ao Māori
No recorded Māori name distinguishes the red lace algae from other red seaweeds. It was likely grouped with other red seaweeds called karengo. The delicate, lace-like fronds would have been noticed. They looked like the finest weaving. Like the work of a master craftsperson. They were a reminder that the sea has its own art. Its own patterns. Its own beauty. The red lace algae was sometimes used as a decoration. The delicate fronds were gathered and dried. Then used to adorn the hair or woven into garlands. Today the red lace algae still grows on the rocky reefs of New Zealand. A flash of pink in the shadows. Soft and flexible to the touch. The delicate one. The lacy one. The one that proves the sea has its own kind of lace.
The water is clear. The light filters through. Delisea pulchra grows. Red lace algae is the delicate one. A seaweed that looks like it belongs in a window. Not on a reef. It grows flattened, branching, finely divided fronds. With a lace-like or net-like appearance. The colour is a beautiful pinkish-red. Sometimes with purple highlights. Fronds are soft and flexible. Waving gently in the current. It looks like something that might be hung in a window. Not something that grows on a rock. A plant that belongs in a craft shop. What makes it special is the defence. Soft and delicate. A tempting meal for any hungry sea creature. But it has a secret weapon. It produces chemicals called furanones. These deter grazing by sea urchins, fish, and other herbivores. These chemicals interfere with the ability of bacteria to communicate with each other. The algae is not just defending itself. It is also preventing bacteria from settling on its surface. A plant that fights with chemistry. Reproduction happens by releasing spores from specialised structures on the fronds. Produced in small, raised bumps on the surface. Red lace algae provides habitat for small invertebrates. Tiny crustaceans hide among its fronds. Small snails graze on its surface. But they are careful. The chemical defences make it a less appealing meal. A plant that shelters others while protecting itself. To find red lace algae is to find a piece of living lace on the reef. Fronds are delicate. Beautiful. Almost fragile. But they are tough in their own way. Armed with chemical weapons that keep grazers at bay. The reef is quiet. The red lace waves in the current. Pinkish-red and delicate. A sea urchin approaches. Then turns away. The chemicals warn it off. The algae does not need to be tough. It just needs to be unappetising. And that is enough. Not Threatened. Common on rocky reefs throughout New Zealand. Particularly in clear, sheltered waters. Often grows on vertical rock faces and under overhangs.