The dogwhelk feeds primarily on mussels and barnacles. When presented with the strong shell of the mussel the dogwhelk uses its radula to bore a hole in the shell. Shell drilling is a two-stage process. First a the snail softens the shell by secreting a fluid onto the shell. This fluid is produced by the snail's accessory boring gland. The radula is then used to scrape away the softened shell. Once a hole is formed the whelk inserts its proboscis (pro-boss-kiss) which contains its mouth and applies the radula to the flesh, scraping it into its mouth. Remember the holes you saw in the previous slide? The diagram to the right above illustrates how the radula works. Click on the image to see a larger view.