Zonation on a shore by Pádraig McCann

Because the distance that the tide comes up the shore varies from day to day, this provides different environmental conditions, and therefore different habitats supporting sea creatures and plants, together with the animals that will be present when the conditions and availability of food suit them.

Splash Zone
The very highest zone on the shore is called the splash zone.
Here you will find a few species of lichen which are fed on by two very small species of winkle.
 
Upper Shore Zone
This zone is only immersed by the spring tides, and then only for a short time. The brown seaweeds, Spiral Wrack has adaptations to prevent drying out and can survive when the tide is out. Acorn Barnacles settle in this zone.
 
Middle Shore Zone
For half the day the tide will be in, even during the period of neap tides.  The common brown wrack of this zone is the Bladder Wrack,. Mussel beds will form and both limpets and periwinkles will graze the rocks. Beadlet Anemones are resident.
 
Lower Shore
For most of the day the sea will cover this part of the shore, so that the beachcomber will need to consult his tide tables to ascertain when the shore is accessible.
This will be longest during the spring tide period. The important brown seaweed is the Serrated Wrack which straddles large areas where there are suitable attachments.
The range of crabs, molluscs, small fish and prawns is much greater in this zone.

For more information see http://en.wikipedia.org/wiki/Intertidal_zone




Shore Zonation