The Costate Horn Snail, Cerithideopsis costata (E.M. da Costa, 1778) is the smaller "sister" to the larger Ladder Horn Snail, Cerithideopsis scalariformis (say, 1825), a species covered in this column on January 13, 2017. Costate Horn Snails may grow to be a little more than 0.5 inch in length. The two species are the only local members of the Horn Snail family Potamididae, a group of marine snails highly adapted to living in brackish waters. Accordingly, the Costate Horn Snail is most commonly found living in the muddy backwater of the local bays and estuaries, but shells may also be collected on the local Gulf-facing beaches.
The Costate Horn, Cerithideopsis costata, from Pine Island Sound, North Captiva Island. Photo by José H. Leal.