Shape and growth in European Atlantic <i>Patella limpets</i> (Gastropoda, Mollusca). Ecological implications for survival

Abstract

Specimens of <i>Patella intermedia</i>, <i>Patella rustica</i>, <i>Patella ulyssiponensis</i>, and <i>Patella vulgata</i> were analyzed for shell and radula characteristics. Shell growth in <i>P. rustica</i> and <i>P. ulyssiponensis</i> was basically isometric, indicating that shell shape was constant during growth. On the contrary, shell growth in <i>P. intermedia</i> and <i>P. vulgata</i> 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 <i>P. ulyssiponensis</i>, <i>P. vulgata</i>, <i>P. intermedia</i> and <i>P. rustica</i>, 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 <i>Patella</i> 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, <i>P. rustica</i> shells displayed the lowest ratios, and <i>P. ulyssiponensis</i> 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

Holocene coastal change and intertidal mollusc exploitation in the central mediterranean: variations in shell size and morphology at Grotta d’Oriente (Sicily)

“…Shell length (SL), width (SW), height (SH; only for P. caerulea/ulyssiponensis) were measured using a digital calliper accurate to 0.01mm (see Figure 1C for morphometric parameters). Shell shape was investigated using SL/SW ratio (Menzie et al, 1992) for O. turbinatus and SH/SL ratio (Cabral & da Silva, 2003;Cabral, 2007) for P. caerulea/ulyssiponensis. A conspicuous number of shells were considerably broken or partially fragmented.…”

Quantifying the Geometric Shell Shape between Populations of True Limpets Lottia Mesoleuca (Mollusca: Lottidae) in Colombia

“…The ventral view is perhaps the most variable in shape, which may be caused by differences in the type of rock that each population predominantly lives upon. Variation in rock type may be associated with ontogenetic variation [49][50][51], showing, therefore, that similarities are in the individuals from Morro Chiquito and Palma Island, followed by those from Gorgona Island and the least similar ones in Los Negritos. Once the Euclidian distance matrices for similarity have been completed, the analysis for grouping by the Ward method was conducted, which is more discriminatory, in order to determine the grouping levels.…”

Acumulações de conchas mortas de moluscos na ilha da Ínsua (Caminha, Portugal)

“…A ausência de parte mole, a erosão da concha e a degradação dos pigmentos não permitiu uma identificação específica segura destas conchas. No entanto, pela morfologia e morfometria, podemos dizer com grande margem de segurança que seriam representantes das três espécies dominantes nesta região: Patella intermedia, Patella vulgata e Patella ulyssiponensis (Cabral, 2003(Cabral, , 2007Cabral & Simões, 2007).…”