Aquascope Facts
Cliff and rocky beach ecology
Shellfish, mussels and barnacles are examples of organisms that use rigid and hard material in their shells. They use perianth that is hard and rigid, but is also heavy and brittle, therefore the perianth is usually mixed with different organic compounds, for example proteins and polysackarides. These compounds make the shell lighter and tough.
    Flexible material, can be composed of a mixture of different organic compounds and is used by many algae, hydroids and anemones. Even small waves can make these organisms bend and change shape, but their flexibility prevents them from being injured. Because they can change their form, there is less risk of them being torn lose from the rocks. This is because the currents give the organism such a form that has so little resistance against the water as possible.
    To not be washed away, many organisms are permanently attached to the rocks since they were very young. Examples of such organisms are seaweed, Pomatoceros triqueter and Clavelina lepadiformis. Other organisms make sure they have a strong anchor that they can release when they want to move.

Littorina littorea foot 7,8 kB
Blue mussels for example can cut their byssus threads when they want to crawl away with the aid of their food. When they arrive at their new site, they can build a new and safe anchor. Most shellfish have the ability to crawl around, even if somewhat slow. The organ they use to move is known as a foot and is very large in relation to their body size and enables them to attach to the bottom very well. In spite of this ability, they often look for sheltered micro-environments such as cracks and crevices to inhabit.
    Shore crabs move much quicker than shellfish, but their ability to attach to rocks and cliffs is poor. The only way they can prevent themselves from being washed away is to take cover in different nooks and crannies.

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Cliffs and rocks are fantastic!
Zoning and flecked occurrence
Animals that are attached
Modular construction
Variation and change
Variations in water level
Wave exposure
Both cliffs and rocks
Freshwater and saltwater
Geography, climate and history
Organisms life cycles
Organisms effect on each other
Energy and the flow of material

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Bo Johannesson | Martin Larsvik | Lars-Ove Loo | Helena Samuelsson