Some limpets spend much of their life in the splash zone, above water
level while others live below the low tide line.  In Hawaii, one Patella
species lives higher on rocks than a similar species.  Their placement
seems a characteristic of the species [my conjecture: this  may be
determined by the gill characteristics].  See Kay, 1979: Hawaiian Marine
Shells, pages 43 to 46.
--
                     Aloha from Wesley M. Thorsson
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