|On variation in Nucella lapillus (L.): shell shape in populations towards the southern limit of its European range|
Crothers, J.H. (1977). On variation in Nucella lapillus (L.): shell shape in populations towards the southern limit of its European range. J. Moll. Stud. 43(2): 181-188
In: Journal of Molluscan Studies. Oxford University Press: Reading. ISSN 0260-1230, more
Gastropoda [WoRMS]; Muricidae Rafinesque, 1815 [WoRMS]; Nucella lapillus (Linnaeus, 1758) [WoRMS]; Marine
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The common Dog-Whelk of North Atlantic rocky shores, Nucella lapillus (Gastropoda: Muricidae), is a slow-moving carnivorous snail feeding mainly on barnacles and mussels. There is no planktonic dispersal phase in the life cycle and as the species is usually restricted to the intertidal zone and does not crawl over sand or mud it has formed innumerable discrete, breeding units around coasts. These populations have had time to diversify and to evolve particular characteristics. Even a casual observer may notice surprising differences between adjacent populations. Variation in shell colour (discussed by Berry & Crothers, 1974) is probably the most striking but it has long been known (Cooke, 1895) that there is also variation in shell shape according to the exposure of the shore to wave action: animals from exposed headlands tend to have short squat shells in comparison with those from sheltered inlets which have relatively long spires.