those that modify the behavioural of an organism. Those species that are best
adapted to take advantage of a set of conditions will do far better than those
that are not adapted will. This survival of the fittest leads to wide diversity
of species found on the seashore. The main factor affecting the species found in
the splash zone is that although it lies above the EHWS mark, and is therefore
never covered by the sea, it is regularly covered in salt spray from waves and
the wind. This prevents many terrestrial species from living there, as they
cannot tolerate areas of high salinity. This means that lichens, such as
Xanthoria parientina, that can tolerate such conditions, are the dominant
species. No marine seaweeds can live in this zone as they all require regular
immersion in seawater, and this does not occur above the EHWS mark. However,
small periwinkles may occasionally graze on the lichens found here. The main
factors affecting the upper shore are the highly variable temperature, and the
amount of desiccation that organisms have to endure as a result of their
infrequent immersion in the sea. However, wave action and the light that reaches
seaweeds are not major factors are waves do not cover this area regularly, and
even when it is submerged, it is not submerged deeply, so the light is not
affected. Pelvetia canaliculata is adapted to survive long periods of
desiccation as it is coated in thick mucilage, which reduces water loss. The
thick mucilage layer also helps to regulate the temperature of the seaweed. It
has channelled fronds, which helps reduce the surface area of the fronds that
are exposed to the air. The enzymes and pigments found within it are also
resistant to sudden temperature change, so it is well adapted to live on the
upper shore. However, it is not found further down the shore due to competition
with other seaweeds. Littorina saxatalis can cope with low temperatures far
better than it can with high temperatures, so it has a ridged shell surface to
increase its surface are and therefore the amount of heat that it radiates. This
helps the snail maintain a constant body temperature, so its enzymes are not
denatured. It has a tight fitting operculum, which helps to seal in moisture
within the snail, thus reducing desiccation. All of the main abiotic factors
affect the Middle Shore. Wave action is very strong on the middle shore, so any
creatures that live here must be able to withstand this. Desiccation and
temperature change are also important factors as the middle shore is regularly
exposed to the air. The main seaweed found in the middle shore is Fucus
vesiculosus, which has thick mucilage to conserve water. The enzymes and
pigments within are also able to withstand a certain amount of temperature
shock, though not as much as those found in Pelvetia canaliculata. It is very
firmly attached to the substrate material, and so is able to withstand the wave
action. Grazing by limpets and periwinkles is not a major problem on this shore,
so the seaweed cover is very abundant. It is not found in the upper shore, as it
cannot cope with the extremes of temperature and the lack of water in that zone.
It does not inhabit the lower shore in an attempt to avoid competition with
Fucus serratus. Littorina obtusata can withstand the moderate amounts of
desiccation and temperature change on the middle shore by closing its operculum
to seal in moisture and by resting under seaweeds to insulate it. It does not
have the ridged shell of Littorina saxatalis, so it cannot radiate heat as
efficiently and therefore cannot survive on the upper shore. By remaining on the
middle shore, Littorina obtusata can avoid predators such as dog whelks that
live further down the shore. However, 12 Littorina obtusata were recorded in
12th station, just above the ELWS mark, which is very unusual, as they are
normally out competed by lower shore snails such as Gibbula cineraria in that
region. The conditions on the lower shore are most like those in the sea. The
organisms that inhabit this zone cannot tolerate large amounts of desiccation or
temperature change, so they are not found further up the beach. As they are
submerged for long periods, the amount of light reaching the seaweeds is an
important factor and only those with the appropriate accessory pigments can
survive here. Predation is far more of a problem for the animals that live here.
Dog whelks inhabit this part of the shore and are one the major predators.
Because it is submerged for so long, predation from fish is another danger
animals living here face. Fucus serratus is very efficient at using the
resources that are in short supply, so it out competes other species, such as
Fucus vesiculosus and Pelvetia canaliculata. However, rapid temperature changes
destroy the photosynthetic pigments in its cells, so it is not found further up
the shore. It is brown in colour and so is very well adapted for taking
advantage of all the available wavelengths of light that reach it. Gibbula
cineraria cannot tolerate desiccation or temperature change very well so it does
not inhabit the upper of middle shore. However, it is very good at maximising
the resources around it, so it out competes other species of snails, such as
Littorina saxatalis. It has a thicker shell than many other snails, and so is
more difficult for predators to eat. Limitations The method that was followed
had a number of limitations that lead to anomalous results (such as finding
Littorina obtusata in the twelfth station). The limitations affecting the
results were: ? The misidentification of species. Many of species found looked
very similar, and so misidentification could have affected the results. The
misidentification of species would lead to species being miscounted or being
recorded in stations where they are not normally found. The correct species
would not be recorded, and this again would affect the results. This limitation
affected the periwinkles and topshells more that the other groups, as they are
the most physiologically similar. ? Species or specimens being miscounted or
missed altogether. Due to the thick seaweed cover on the shore, it is possible
that many of the periwinkles and topshells where either miscounted (as
individuals were covered up) or missed altogether. Quadrats containing many
cracks or crevices, or large rocks, which organisms could hide under, also made
it more difficult to be confident that every specimen had been recorded, leading
to inaccurate results. ? Quadrats being placed in the wrong location. It would
have been easy for errors to have been made while cross-staffing new locations
for quadrats, which would lead to species being recorded at the wrong heights
and in the wrong zones. This would make it harder to draw meaningful conclusions
from the results. ? Quadrats placed on uneven ground. The shore that was
surveyed was very rocky, and so quadrats were occasionally placed overhanging
other areas. This lead to larger areas being surveyed, as the slopes were
surveyed as well as the flat ground. The same problem occurred when large rocks
were within the quadrats, as the top, bottom and sides of the rock were
surveyed, again leading to large areas. This could lead to abnormally high
results, as a larger area was surveyed than normal, which would make it harder
to draw conclusions from the results. ? Animals moving around. The majority of
the animal species recorded are mobile, and so could move around while being
counted, leading to inaccurate results, or could have been found far from their
niche, distorting the results. The animals could move into a quadrat, leading to
higher results, or move out of a quadrat, leading to lower results than would be
expected. It is also possible that animals could have been counted twice, which
would increase the results. All of these limitations would affect the accuracy
of the results, making it harder to draw meaningful conclusions. Biological
Significance An organism can only survive in a particular habitat if it is well
adapted to that habitat. If a organism arrives in a habitat to which it is not
adapted, then it will be either killed outright by the conditions there (e.g.
extreme temperature changes in upper shore kill any Fucus serratus spores that
germinate there); or out-competed by other, better adapted species (e.g.
Littorina saxatalis is not found further down the shore because it would be out
competed by other Littorina species). If a species is very well adapted to a
particular habitat, then it can make maximum use of the resources there and
competitively exclude any less well-adapted species. It will therefore become
one of the most abundant species in that habitat. Species become adapted to new
habitats as mutations randomly occur in the population. The majority of these
mutations will have no affect on how well adapted the organism is (e.g. a human
being born with webbed toes), some will make it less well adapted (e.g. a bright
white lion is born and is unable to be camouflaged against its prey and so
starves), and others may make an organism better adapted to its habitat (e.g. a
giraffe is born with a longer neck and so can reach more food). Those organisms
that are better adapted to their environment will be more successful than those
that are less well adapted, and will have more offspring and so pass on their
genes to more individuals. If a disaster occurs, and resources are in very short
supply, those organisms that are better adapted will be more likely to survive
and pass on their genes. Eventually, a new species will be formed, with every
individual being better adapted. When this occurs, the original species may
become extinct (e.g. all the giraffes with short necks), or continue surviving
if the new species is adapted to take advantage of a different habitat (e.g. a
new seaweed evolves that can survive higher up the shore). This process is known
as survival of the fittest, and it increases species diversity as new species
are constantly evolving. This can be seen on a miniature scale on the rocky
shore, where many different species have evolved to take advantage of the many
different ecological niches available. My results show that each species is only
found on a small area of the shore, an area that it ha evolved to be adapted to,
and one where it is the most successful species. This process of evolution is
constantly occurring, producing better and better-adapted species, for many
different ecological niches. It occurs all over the globe in many different
habitats, forming many new species.