Red algae (Rhodophyta) are a large group of mostly marine organisms ranging from tiny filaments to substantial leafy seaweeds. The group includes thousands of species, several of which are commercially important as food or as sources of gelling and thickening agents.
Edible red algae include nori (Pyropia/Porphyra species, used to wrap sushi), dulse (Palmaria palmata), and Irish moss (Chondrus crispus). Industrial red algae species are the source of agar and carrageenan — hydrocolloids used extensively in food manufacturing as gelling agents, stabilisers, and thickeners.
In Australia, various native red algae species grow along the southern coastline. While direct consumption of red algae is less common in Australian food culture than in East Asian traditions, agar and carrageenan derived from red algae are found in a wide range of processed foods.
How it's produced
Red algae are both wild-harvested and farmed. Wild harvesting involves collecting seaweed from coastal rocks and shallow waters by hand or with simple raking tools, typically at low tide. This remains common for species like dulse and Irish moss in Atlantic coastal communities.
Aquaculture of red algae — particularly nori and carrageenan-producing species — is a major global industry. Nori farming, centred in Japan, China, and South Korea, uses nets or lines suspended in sheltered coastal waters where spores are seeded, grown, and harvested over several months. Carrageenan-producing species like Eucheuma and Kappaphycus are farmed extensively in Southeast Asia, grown on lines in shallow tropical waters and harvested by hand.
What it costs the planet (per kilo)
≈ Estimated from its category — typical for vegetables, not measured for this item yet. Sources & methods →
What comes from this
Your household's take
One thumb per person, shared with your household — it steers what the wider-web shelf and the swap chips offer you. Tap again to take it back.
✎ Spotted something wrong? Suggest a correction
Checking who you are...