The intertidal
rocky shore is an extreme habitat that is in a state of almost constant
change when compared to land or the sea.
Due to water
movements associated with tides, waves and spray, conditions affecting
different levels on the rocky shore vary continuously throughout
the day.
Coralline algae
and smooth limpets
Exposure
to air is stressful to marine organisms just as submersion in water
is stressful to terrestrial species. Most species on the rocky shore
gain oxygen through moist gills and require strategies to ensure gills
are kept moist.
Not surprisingly,
most of the physical stresses affecting marine organisms in
this environment are associated with exposure to air and potential
desiccation. An additional limiting factor can be exposure
to waves that create shear forces on the rocks and could potentially
dislodge organisms.
Other
physical factors influencing distribution could include changes
in salinity, dissolved oxygen levels, and substrate type and
availability of shelter.
