T'idal Zone 



105 



The upper part of the Littorina Zone extends into the spray zone, or 

 supralittoral zone, where the salt-resistant outposts of the land fauna 

 and flora are to be found as well as those marine organisms most 

 capable of enduring desiccation (Boyce, 1954). The Laminarian 

 Zone extends for varying distances below low-tide mark. 



Barnacles 



Slfplunson and Slcphcnson, I'H'J, copyiiglit Cambridge University Press 



Fig. 4.5. Diagram to illustrate the three fundamental zones of life between tide 

 marks on a rocky shore, showing subdivisions typically encountered on British 



coasts. 



Frequently various subdivisions are superimposed on the main 

 zonation of rocky shores ( Fig. 4.5 ) , The vertical limits of the various 

 subzones of fucoid algae and of associated invertebrates are deter- 

 mined not only by relative tolerance in respect to the water factor 

 but also by type of rock, wave action, and relative success in invasion, 

 competition, and resistance to predation. 



