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The
shore
crab is an example of an organism that is found along cliffs, but is
even more common on beaches composed of rocks and boulders. This is probably
because it is easier for them to find a haven where they will not be washed
away, taken by birds and that there is probably more food to be found.
On peeble beaches, the wave energy is so great that even large
rocks and boulders are sat in motion, so much so, that they are heard hitting
and rubbing against each other. It cannot be so easy staying alive in a
pestal and mortel. Therefore, peeble beaches are rather poor in fauna within
the surge zone. Micro-organisms
are however found here, thanks to their small size and quick rate of growth.
These micro-organisms are difficult to see, but their presence is felt because
the rocks can feel slimy and slippery. Occasionally the peebles can be coated
with a fast growing alga that is larger.
The waves damaging effect on beach living fauna is greatest
when the waves are strong enough to move rocks and boulders. Organisms can
get disorientated, especially when the topside of the rock has became the
underside. On some beaches, especially those that have a low gradient, not
so much damage is caused by the waves as they break on irregularities further
out. Alot of the waves energy is also absorbed by small movements of the
rocks.
| The rocks in the left-hand picture have been thrown
up by storm waves, which is seen by the white patches of dead encrusting
algae. The rocks on the right are more protected from the waves.
On and around them there are many living organisms. - The white
patches are living barnacles. |
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