tubes up in the shaded reef crevices

Size
Height: 5–15 cm
Lifespan
2–5 years
Diet
Photosynthetic. Draws energy from sunlight and nutrients from surrounding water. Requires clean water and good flow.
Habitat
Grows on rocky reefs in low intertidal and shallow subtidal zones, often in shaded crevices and under overhangs. Forms soft, inflated, branching red tubes that look like sponge or coral.
Range
Found throughout the North and South Islands on rocky reefs in low intertidal and shallow subtidal zones. Most common in clear, sheltered waters with good water flow. Also found in temperate regions worldwide.
Endemism
Endemic
Main Threats
None significant. This species is common and widespread. Localised threats include coastal development, pollution, and climate change affecting water temperature.
Population
Not Threatened. Red sponge algae is common on rocky reefs throughout New Zealand, particularly in shaded, sheltered locations. It 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
Endemic 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 sponge algae from other red seaweeds. It was likely grouped with other red seaweeds called karengo. The soft, red tubes would have been noticed. They looked like the guts of a fish. Like the tentacles of a sea creature. Like something that should not be touched. They were a reminder that the sea is full of strange things. Things that do not fit into easy categories. The red sponge algae was sometimes used as a poultice. The soft, gelatinous tubes were applied to wounds and skin infections. To soothe and heal.
Touch it. It feels wrong. Champia novae-zelandiae does not look like seaweed. It has fronds that are soft, inflated, branching tubes. Hollow and gelatinous. Like small red sausages or fingers of sponge. They are bright red to pinkish-red. Sometimes with a translucent quality. They look like they belong in the animal kingdom. Not the plant kingdom. They look like sponge or coral. Or something you would find in a tide pool that you would not want to touch. It is the alga of the strange shape. The one that blurs the line between plant and animal. What makes it special is the texture. The red sponge algae is soft and gelatinous. Filled with a jelly-like substance. It is not crunchy like the sea moss. Or leathery like the ribbon kelp. It is squishy. You can press it between your fingers. Feel it give. Then watch it slowly spring back. It is the jelly of the seaweed world. The one that is soft and yielding. The one that feels like it should be alive. The red sponge algae is a red alga. A member of the Champiaceae family. It is one of the few seaweeds that is truly hollow. Its branches are tubes filled with a gelatinous fluid. This fluid helps the plant stay upright in the water. Providing buoyancy without the need for air bladders. Under a hand lens, the tubes are beautiful. Translucent and filled with a pinkish gel. Biologically, the red sponge algae reproduces by releasing spores from specialised structures on its fronds. The spores are produced in small bumps on the surface of the tubes. To find red sponge algae is to find a cluster of soft, red tubes in the shadows. They look like sponge. Like coral. Like something from a different world. You can touch them. Feel their squishy texture. Watch them spring back. It is the jelly one. The sponge-like one. The one that looks like it belongs in a different kingdom. The one that proves that the sea is full of things that defy easy categories. Not Threatened. Red sponge algae is common on rocky reefs throughout New Zealand. Particularly in shaded, sheltered locations. It often grows on vertical rock faces and under overhangs.