Frilled Dog Whelk (Nucella lamellosa)
This snail reaches great abundance in the intertidal zone of Pacific Northwest shores, where it can easily be found resting on rocks when the tide is out. Beginning beachcombers will be convinced they have found numerous species, as this species seems to be one of the most variable gastropods known. The largest individuals produce shells up to 10 cm in length.
The fairly thick shells vary from smooth to longitudinally wrinkled to very strongly ridged. The relative breadth of the shell varies greatly, from slender to more chunky. Some have obvious “teeth” along the outer edge of the aperture, while others lack them completely. Color variation is extreme, from pure white to golden to rich brown to almost black and with many variations in striping patterns around the shell. Some of the striped forms are quite handsomely patterned.
Some of the types are more common at certain sites, so a superficial survey will lead one to believe that the differently shaped shells are characteristic of different habitats or regions, but with increased scrutiny, more and more variation is found at a single place.
When submerged, this species cruises slowly along on rocks or other hard surfaces such as pilings. It is a carnivore, feeding on shelled invertebrates, including bivalves and barnacles, which it penetrates by scraping with its hard radula. It then releases digestive enzymes into the hole, quickly digesting prey tissue and sucking up the "soup." It may also feed just by inserting its proboscis, with mouth on the end, into a gap in a shell.
In turn it is food for all of the snail-eating vertebrates, including goldeneyes and other ducks, and Ochre Sea Stars, which seem to eat anything.
Frilled Dog Whelks congregate in groups to breed in spring, when they attach clusters of stalked egg capsules to their rocky substrate. Each capsule contains numerous eggs. Not only do the adult whelks eat the eggs of their own and other species, but the first-hatched young will eat the eggs of their unhatched siblings.