Carrageen/Irish moss (Chondrus crispus)

Carrageen (Chondrus crispus) ©Devon WT


Carrageen ©Kirsten Smith


Scientific name: Chondrus crispus
This small reddish-purple seaweed grows in small branching fans on rocky shores. It is widely used in the food industry - and might have been used to produce your ice cream, beer or even jelly!

Species information


Length: up to 20cm

Conservation status


When to see

January to December


Carrageen is a common seaweed found on rocky shores and in estuaries. It is small and branching and is also known as Irish Moss. It is usually reddish-purple in colour, though is can be a greenish-yellow. The fronds can appear iridescent blue when underwater - beautiful!

How to identify

Carrageen is a thin, reddish-purple seaweed, with branching fronds. The fronds may appear iridescent when submerged and can turn green if exposed to bright sunlight for prolonged periods. It does not have air bladders.


Common on rocky shores all around our coasts.

Did you know?

Carrageen is harvested commercially for its carrageenan - a polysaccharide molecule that is used in the food industry for gelling and thickening. So, it might be in your ice cream or have been used for fining your beer or wine! It has been used since the 15th Century and is a vegan alternative to gelatin.

How people can help

Seaweeds provide a vital link in the food chain for many of our rarer species. Our seas and coastline are in need of protection if we are to keep our marine wildlife healthy. The Wildlife Trusts are working with fishermen, researchers, politicians and local people towards a vision of 'Living Seas', where marine wildlife thrives. Do your bit for our Living Seas by supporting your local Wildlife Trust.