摘要：Specimens of Patella intermedia, Patella rustica, Patella ulyssiponensis, and Patella vulgata were analyzed for shell and radula characteristics. Shell growth in P. rustica and P. ulyssiponensis was basically isometric, indicating that shell shape was constant during
growth. On the contrary, shell growth in P. intermedia and P. vulgata was positively
allometric, indicating that as shells increased in size, the base became more circular and
the cone more centred and relatively higher. Radula relative size increased in the order P.
ulyssiponensis, P. vulgata, P. intermedia and P. rustica, and had negative allometric growth
in all species, indicating that radula grew less as shell increased in size. Data reported in
the literature estimated that the lowest risk of dislodgment for a limpet is associated with
a centred apex, and a (shell height)/(shell length) or (shell height)/(shell width) ratio of
ca. 0.53. However, as reported for other limpets, in all four studied Patella species, shells
were more eccentric and flat than this theoretical optimum. Data reported in the literature
indicated that, in limpets, decreasing the (shell base perimeter)/(shell volume) or
(shell surface area)/(shell volume) ratios by increasing size results in lower soft body
temperature and desiccation. In the present study, P. rustica shells displayed the lowest
ratios, and P. ulyssiponensis shells, the highest. Considering that the former species lives
at high shore levels, and the latter species at low levels, it appeared that shell shape in
European Atlantic limpets can be directly related to resistance to desiccation and high
temperature stresses. Radula relative size (in relation to shell height) also increased with
increasing level in the shore, suggesting that this might be due to a decreasing abundance
of algae with increasing shore level.
