Aquascope|Facts|Cliff and rocky beach ecology 6

Animals that are attached

This creature is both attached and a colony builder. It is a hydroid known as Kirchenpaueria pinnata and can be up
20 cm tall.

Many cliff and rock living creatures are quite different compared to the animals we commonly see such as horses, fish, crabs and possibly sea urchins . Because in the sea and especially on cliifs, the different creatures are often attached to the substrate and sometimes several individuals sit together and build colonies. This results in that many of these creatures have a very different appearance compared to land based creatures that may for example run around.
The ability to survive without being able to move is dependent on the fact the sea water takes care of all the transport. Many creatures do not need to move to a partner to be able to reproduce as they can release large quantities of eggs and sperms directly into the water. Water currents carry these products together to enable fertilization. The same water currents also carry food to the different animals.

Food has to arrive

It can be a great advantage for organisms to live attached to the substrate and rely on the water currents to transport food to them as they do not have to spend energy on hunting or finding food. Another reason that makes it advantageous to live attached to the rocks is that there is less risk of them being washed away and thrown up onto the beach by the waves. Because the food these organisms eat hovers in the water, they are known as suspensions feeders. Examples of attached suspension feeders are: dead men´s fngers, northern rock barnacles, polychaetes and sea squirts .

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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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© Aquascope 2000 Tjärnö Marine Biological Laboratory, Strömstad, Sweden
Bo Johannesson | Martin Larsvik | Lars-Ove Loo | Helena Samuelsson