Identify that Mollusk

Given the confusion over the Queen Conch photograph I recently pointed out, I was looking at gastropod pictures via Google Images. I ran across this page that supposedly pictures a Florida Fighting Conch (Strombus alatus), a common conch species. However, I think they’ve misidentified this gastropod. Given the picture, I think it is much more likely to be the Crown Conch (Melongena corona), an even more common gastropod of Florida’s bays and inshore waters.

Some clues are handy. There is the nearly-oval operculum seen in the photo. Melongena corona are commonly exposed during low tide, and the operculum makes a pretty good seal with the shell, preventing the snail from drying out too rapidly. By contrast, strombid opercula are usually sickle-shaped, and do a poor job of sealing the aperture when the snail retracts into the shell. The shell structure is overall lighter than in the strombids. There is a series of raised flutes near the anterior end of the shell, which are absent in Strombus alatus. There is no strombid notch, the gap in the line of the outer edge of the shell that a strombid uses to extend its stalked eye through when the whole shell rests on a sandy bottom.

The two species differ in more than shell morphology. The strombids feed on algae and detritus, but the Melongena corona are important predators of various species of bivalves. Melongena spp. have a very long proboscis with scraping radular teeth. Once they are able to weaken a bivalve and insert the proboscis, it is game over for the bivalve. Keeping a few of these snails in a tank meant that I could have cleaned-out bivalve shells any time I wanted, plus they don’t bore a hole in the bivalve shell like the moon snails do.

Of course, I’m reaching back about thirty-five years to when I was actively visiting the Gulf of Mexico or the Atlantic Ocean around Florida, and these mollusks were all good acquaintances of mine. I looked for an email address for the person credited with the page, but wasn’t able to find it.