Rocky shore lichens guide
The FSC Rocky shore lichens guide features 62 common species of lichen found on rocky sea shores, from the low tide mark up to the limit of sea spray.
Colour photographs of all the rocky shore lichens illustrate the key features to spot. On the reverse side there is an easy-to-use visual lichen identification guide.
Generally the rocky shore is a very difficult environment for most living organisms. Below high tide mark, the sea submerges the shore for part of the day. Above high tide mark, breaking waves soak surfaces with salty spray. When this spray dries out it leaves a coating of salt. Overall lichens are some of the relatively few organisms that can survive these challenging conditions.
Often the seashore is divided into several zones.
- Lower shore – only uncovered at low spring tides. There are few lichens. Lichens do not occur below this level, as they need light for photosynthesis.
- Middle shore – covered and uncovered twice a day by the tide, so wave action is powerful. Thus the few species that survive grow inside shells or they are smooth and crustose.
- Upper shore – rarely submerged by the tide. Black tar lichen is often dominant. Indeed the upper shore is sometimes called the ‘black zone’.
- Splash zone – never submerged, only affected by spray. This zone contains many colourful Caloplaca species, and is sometimes called the ‘orange zone’. It merges into the ‘grey zone’, where mainly grey lichens grade into normal inland lichens.
Lichens are present throughout the year, so you can search for them at any time, even in the winter. You do not need to take any special equipment with you, although a hand lens or magnifying glass are useful, since some key features are small and difficult to recognise.