nassarius

What is the difference between a whelk and a Nassarius snail?  In the picture below, the creature on the left is a Nassarius snail, the one on the right is a whelk. Whelks get much larger, while Nassarius don't. At least Nassarius vibex, that is.  And all the images at the top of this article are Whelks, an unwanted snail in a reef system. Read on...