The major part of the beach at Eype is made up from small size shingle and pebble with scattered large boulders that have rolled across the beach from landslips along the cliffs. However, if you walk westwards along the seashore, the number of boulders increases until the far point is entirely rocky shore from the base of the cliff down into the sea. It is on these rocks and boulders between the extremes of tide that the seaweeds grow.
Strangely, not all of the rocks in the intertidal zone are colonised by algae. Seaweed seems to have definite attachment preferences. The large flat rocky surfaces are the most likely habitat to be occupied – as are large boulders that are constantly splashed and frequently submerged at lower levels of the shore. The seaweeds of different types that cover the flat-topped rocks make interesting patchworks of diverse colour and varying textures.
The most common seaweed is the olive-green Toothed Wrack, Fucus serratus, which is actually a member of the brown seaweed group or Phaeophyceae. Bright splashes of colour are provided by shapeless masses of soft green seaweed, probably Gut Weed Enteromorpha intestinalis, which belongs to the Chlorophyceae group. Pepper Dulse, Laurencia pinnatifida, is easily recognised by its wonderful golden hue, although it is actually a red seaweed belonging to the Rhodophyceae. Soft filamentous red seaweeds that are difficult to individually identify are responsible for extensive areas of pink or purple-brown colour; these provide a counterpoint and contrast to the other types of basically green to yellow algae.
Revision of a post first published 7 February 2010
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Oh my goodness, gorgeous seaweed. Or algae. Who would have thought about seaweed preferences? Amazing.
It is amazing but all living creatures do have habitat preferences – in fact, not so much preferences as requirements. This accounts for their different distributions across the surface of the globe. On the seashore, where habitat preferences are very much influenced by changing level of the sea, this leads to vertical zonation of the invertebrates and seaweeds, regardless of substrate. Different species occupy different places on the beach from the lowest, permanently underwater, to the highest that is only splashed by the waves at high tide.