Growth rate
Value given is the maximum rate of increase in shell length observed in the first year of growth by Blackmore (1969). From the findings of many workers however, it is clear that growth fluctuates from year to year and from place to place to such an extent it is difficult to make general statements. Growth depends on temperature and is greatest in summer, least in winter. Growth also varies between microhabitats being greater under fucoids (17.1 mm per year) than on barnacles (14.7 mm per year) where locomotion and grazing are difficult. Growth rates and longevity are inversely related. Animals under fucoids grow rapidly and may live only 2-3 years whereas those on bare rock, with little food, grow slowly but may live 15-16 years. Limpets move about when the tide is in and the sea is not too rough. Animals are more active when submerged due to the lower energetic cost of moving on mucus when under water. Under thick fucoid covering or when conditions are damp, individuals may be found on the move after the tide has fallen.