Tidepool Tim says,  "Ridged whelks are quite common in lobster traps as they are attracted to the fish bait.  We get them in our sampling dredges as well.  In the springtime, they seem to migrate above the low tide line and in March and April they are caught mid-way up the beach and eaten by seagulls.  The gulls carry them high in the air above a pile of rocks and then drop the snail down to its death to be shattered upon impact and allow them a tasty meal.  If the gull misses, he just repeats the airlift/drop until success.  Their egg masses are similar to the waved whelk.  These guys have the perfect little antenna and a proboscis they use to scavenge along the sea-floor looking for dead crabs, clams, fish, or even birds. They too are recycling scavengers that keep the benthic food chain cycling.”