The slow-growing and long-lived sunset cup coral has a porous skeleton (1) about the size of a thimble (2). The polyps are similar in appearance to sea anemones and are bright yellow in colour, reaching up to three centimetres in diameter (2).
Little is known of the biology of this coral. Limited monitoring of populations at Lundy and the Isles of Scilly suggests that settlement of new corals does not occur every year. This is possibly determined by long-term cycles in factors such as water temperature; settlement only occurring in warmer years (4).
Recorded in the north-east Atlantic in the Channel Isles, Brittany and Portugal, it is also found in the Mediterranean. It was first recorded in Britain in 1969 from the island of Lundy, and is now known to occur in a few isolated sites in the south-west of England (1).
In U.K. waters the sunset cup coral reaches the northern limit of its range. This means it probably exists here at the limit of the environmental extremes it can tolerate. Consequently, it may be particularly susceptible to relatively small changes in its environment. For example, slight drops in water temperature may prevent successful reproduction. Populations at Lundy may fail to successfully recruit new corals as Lundy is a small island swept by strong currents. Thus larvae may be carried away before they are able to settle on suitable rock.
The sunset cup coral has been targeted as a priority species by UK Biodiversity Action Plan. The Species Action Plan that results from this process aims to improve current understanding of the life history, range and numbers of the species and to maintain the extent and numbers of all populations discovered by 2004 (1).
The UK Biodiversity Action Plan for this species is available at UK BAP.
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