Slippery hard surfaces and constant waves crashing onto the rocks make this marine environment not only one of the most hazardous to marine and human life, but also one of the most rewarding.

Any creature or plant living in this environment must adapt to the risk of damage from the waves and the effects of the sun. As there is little or no shelter from the desiccation effects (risk of drying out) and the changes in the salinity of the water within rock pools caused by evaporation or precipitation (rain).

The first is living on the rock itself either on the surface or within the crevices caused by water freezing and cracking the solid rock. Animals that live attached to the rocks fall into two categories:

Those that are mobile Limpets, crabs etc...and those that are immobile Barnacles, Mussels etc.. .In both cases they have to have a mechanism by which they remain 'stuck' to the rock preventing them from being washed into the ocean by the waves.

Fish, shrimps and other aquatic animals can also be found in these pools, as they need to be constantly covered in seawater in order to survive, these animals are usually trapped in these rock pools until the tide returns to release them. Other creatures are trapped at each low tide only to be released again when the tide flows back in.

The environmental factors that any organism living in this environment need to overcome are Desiccation, Salinity and Temperature changes, Wave damage as well as Predatory Factors.

This becomes a problem to overcome if the organism lives on the surface of the rocks and increases the greater the distance from the low water mark. Due to the nature of the system the rock face is usually steep or spread out, meaning the water does not cover the rock surfaces 24hrs a day exposing the organisms to the drying effects of the sun and wind. There are many ways the animals overcome this problem;

One way is to move into the crevices of the rock when exposed, this gives some protection from the sun (in the shade) and protection from the wind. The crevices also retain a higher humidity level than the surrounding environment and therefore lesser the effects of moisture evaporation. This option is only open to mobile organisms.

Sessile organisms such as the Mussel close their shell and form a water-tight seal trapping the moisture within the shell until the next high tide. Other organisms such as the Anemone reduce their surface area by folding in on themselves and therefore reduce their total surface area and reduce evaporation.

Animals either seal there delicate tissues away from the external environment by forming an air and water tight seal (Mussels, Barnacles etc..) or have developed a high tolerance of salinity increase or decreases by regulating there salt content within their body, by various biological methods. In essence controlling the amount of salt which enters or leaves their bodies.

Some methods are simple, like moving from the sun into the shade in crevices etc... much like a human would move from the sun into the shade to cool down (lower temperature environment).

By having strong external shells or soft flexible bodies combined with a strong attachment mechanism the effects of wave damage, or being washed into the ocean can be reduced. Animals may also use the terrain for protection like sheltering in cervices for protection. Algae have strong leathery skins to prevent tearing and drying out but still retain the flexibility so they can move with the waves.

These Common mussels have placed themselves in the crevice of the rock to gain shelter from wave action. This particular group also has the added protection of being directly above a rock pool, which provides protection fron the effects of desiccation due to the increased humidity directly above the water surface.

Animals and algae have developed numerous anti-predatory devices such as hard exoskeletons, mobility and other defences (Claws on crabs, Nematocysts (Stinging cells) on sea anemones etc..) These mechanism are to numerous to mention here as they relate to each individual species.

Limpets live on the surface of the rocks and consist of one shell. They are mobile organism although they move at such a slow pace is difficult to spot by the naked eye, Only the groove trail which they leave in the surface of the rock as they graze the algae gives any indication that they move at all. They can be found attached to rocks (see above) or to the underside of large stones in the lower regions of the shore. Some species can be found as far as 20m below the surface. Limpets are a member of the mollusc family and feed by the use of a radular, a row of hard teeth used to scrap the unicellular algae off the rock surface. These teeth are continually replaced throughout the life of the limpet and are so strong that they ware away the surface of the rock leaving a visible trail on the surface.

A large number of Macro-algae can be found in this Environment. The majority of which have tough leathery outer coating, to protect the plant from the effects of the waves and desiccation.

The most common species to be found in the British waters in this environment is Fucus vesiculosus ( Bladder wrack ) found mainly in the middle shore zone. Bladder Wrack photograph

This seaweed is found attached to rocks, stones, pier piles and so on. Olive brown in colour when dry this changes to greenish black. Can grow up to 3 feet in length and has a short, thick stalk.

The fronds are flat with contain Gas filled bladders (often in pairs) which lift the seaweed towards the light, However where the wave action is high the size of these bladders is reduced and in some cases the bladders my not develop. In older, larger specimens the bladders are smaller but more numerous.

From the shallow water up to the low tide mark Laminaria hyperborea can be found. Brown in colour with a large flat frond. This macro algae can grow up to 2 metres long and 90 cm wide. The frond is situated at the top of a long stalk which at the base is a sturdy holdfast. The holdfast is a cluster of strong, short, thick, intertwining root like processes. The stalk is rough, hard and round in cross-section.

Another seaweed found in the Rocky shore environment is Chondrus crispus (Carrageen). This seaweed is found in Europe, North America (Atlantic coast). The habitat of this species is the Middle shore zone and can be found in Rock pools or fixed to rocks and large mollusc shells. Usually dull dark red or reddish brown in colour but can be red, purplish red or purplish green. The fronds grow up to 6 inches long and up to 1 inch wide. The stalk is short and flat. The morphology of this seaweed depends on the conditions where it is found, The frond is membranous and tough and narrow, almost circular with few branches in exposed areas. In sheltered areas such as rock pools it may be thin and have numerous divisions on its ends. At the base of the stalk is a flat disk holdfast

This change in morphology depending on conditions is evident to some extent in all varieties of seaweed. The more branches and delicate the fronds a species has tends to indicate a sheltered environment, leading up to thick leathery stems with few branches for the more exposed areas. This is due to increased surface area = increased photosynthetic area. However the increased surface area also increases the likelihood of wave damage. Delicate thin fronds also allow more light penetration for the photosynthetic cell beneath the outer layer, but again increase the risk of frond damage. A tough leathery skin protects the cells beneath but reduces light penetration and therefore photosynthesis.

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Bert's Safety Tips An area of my site designed for the young who want to go and find the Marine organisms mentioned on this page. This area contains safety tips whilst visiting this environment.