This red seaweed grows as brownish-red crusts on small mobile stones and pebbles in shallow water. Very rarely, it also grows on loose fragments of hard, coral-like maerl.
The crusts are firmly stuck to the stone and on close inspection have small erect ‘warts’, randomly scattered over the surface. These are the seaweed’s reproductive bodies, which have a range of functions within the seaweed’s complex life cycle.
This extremely rare seaweed is very vulnerable to extinction as it occupies so few locations and the gravel on which it lives could be affected by aggregate extraction.
This red seaweed was previously known only from a few dredged specimens, collected from the French coast, mostly in the last century. It has now been recorded from western Scotland, south-west England, the Welsh coast and a small inlet of Kilkieran Bay, County Galway, Ireland.
UKBAP Priority Species
Species of principal importance for the purpose of conserving of biodiversity under the Natural Environment and Rural Communities Act 2006
Red seaweeds do contain chlorophyll, but also have additional pigments which mask the green colour. These pigments allow red seaweeds to absorb light at the blue end of the spectrum, and so they can be found in deeper water than green algae.