Life at the Edge of the Sea

A study carried out by Joanne Smissen in Victoria has shown that althoughCatomerus settle throughout the intertidal zone, the growth rate varies with height on the shore (ie. height above sea level). Catomerusis abundant in the spray zone, but is found in the spray, intertidal and subtidal zones.

Jo explains the experiment:

To determine whether growth rate varied with tidal height I measured the opercular diameter of 1-year-old surf barnacles at three different levels on the shore. Opercular diameter is a convenient measure of the size of a live barnacle, especially if you need it to be there again next time. I also got very wet!

Opercular diameter reached by barnacles in the first year of adult life was used to indicate growth rates of barnacles found at different sites on Phillip Island, Western Port Bay, Victoria.