With the introduction of the Carcinus maenas, the L. littorea with the thickest shell is strongly selective as an anti-predation technique against C. maenas (Hughes et al, 1979). The shell is the thinnest has lower survival against C. maenas predation, whereas, the thicker L. littorea shell is the bigger their survival rate is.
L. littorea collection was performed at Fitzgerald J V Marine Reserve, Half Moon Bay California. About 120 snails were collected from the rocky intertidal zone, 60 from exposed (waves) shore and 60 from shelter (rocks) shores. Crabs traps baited with raw fish were used to catch male C. maenas between 6-7 mm width also from Fitzgerald J V Marine Reserve. Snails and crabs were kept in aerated tanks filled with water collected from 1km of the reserves. The crabs were acclimated and starved for 24-48 hours to increase their motivation to feed.
Before the trials snail shells were scrubbed clean of algae and measured for shell height (maximum height measured from the apex of the basal inflection of the aperture), shell width (maximum width measured perpendicular to …show more content…
littorea. Sheltered L. littorea were attacked less successfully than exposed snails. The data suggest that thicker shell of L. littorea has a higher survival rate against C. maenas predation compare to the thinner shell of L. littorea. Our results indicate that L. littorea were most likely to be killed in the thinnest shell classes (0.0-1.0 mm), damaged in the middle classes (1.0-1.5 mm), and resistant to shell crushing in the largest class (1.5-2.0 mm). As the thinnest shell L. littorea are killed off, their allele becomes extinct, as they cannot reproduce. Snail shell with the thickest shell survive contribute greatly to the population, eventually increasing their shell thickness because it is beneficial to their survival to increase the cost benefits that comes with
L. littorea collection was performed at Fitzgerald J V Marine Reserve, Half Moon Bay California. About 120 snails were collected from the rocky intertidal zone, 60 from exposed (waves) shore and 60 from shelter (rocks) shores. Crabs traps baited with raw fish were used to catch male C. maenas between 6-7 mm width also from Fitzgerald J V Marine Reserve. Snails and crabs were kept in aerated tanks filled with water collected from 1km of the reserves. The crabs were acclimated and starved for 24-48 hours to increase their motivation to feed.
Before the trials snail shells were scrubbed clean of algae and measured for shell height (maximum height measured from the apex of the basal inflection of the aperture), shell width (maximum width measured perpendicular to …show more content…
littorea. Sheltered L. littorea were attacked less successfully than exposed snails. The data suggest that thicker shell of L. littorea has a higher survival rate against C. maenas predation compare to the thinner shell of L. littorea. Our results indicate that L. littorea were most likely to be killed in the thinnest shell classes (0.0-1.0 mm), damaged in the middle classes (1.0-1.5 mm), and resistant to shell crushing in the largest class (1.5-2.0 mm). As the thinnest shell L. littorea are killed off, their allele becomes extinct, as they cannot reproduce. Snail shell with the thickest shell survive contribute greatly to the population, eventually increasing their shell thickness because it is beneficial to their survival to increase the cost benefits that comes with