A Horse Conch Tale
By Carolyn Petrikin


Our 30 gallon home aquarium has been home to a specimen of the Florida State Shell, Triplofusus giganteus, a brownish Horse Conch, since July, 2005.  We found this mollusc with the gorgeous bright orange animal near Dunedin, Florida one evening on a very low summer tide among some exposed grass.  At the time I wondered if it might be a bit too large for our tank!  Over the past fourteen months, he’s become so fascinating to watch we’ve not returned it back to the bay. 

How I wish we had measured the shell!  My guess is that a little over a year ago it was approximately 5 1/2 inches long and 6 1/2 inches around at the largest part. 

"Horse Conch Looking For His Dinner!"
a Melongena corona is riding on the back of the shell that was to devour it someday after the photo was taken!!
January, 2006

Now, fifteen months later, it’s a whopper in comparison at 7 1/2 inches long, and 9 3/8 inches around!  But what impresses me more than anything about this shell is how heavy it has become!  I picked it up for the first time just recently since placing it in our tank and was immediately shocked to realize this was no longer a “little” shell!

Why is this shell so heavy?  Well, this Horse Conch really has an appetite! 


We can keep very little else in the aquarium, as other molluscs eventually become part of his diet.  There was a True Tulip, Fasciolaria tulipa, already living in the aquarium when the Horse Conch arrived.  The True Tulip is about 4 inches long, and for some unknown reason, has never been approached by the Horse Conch!  But not so for other residents in the aquarium!


I wish I had kept a log from the very beginning, but only began noticing the huge number and variety of molluscs consumed by this fellow earlier this year.  Our Horse Conch has devoured approximately:
  • twenty-five King’s Crowns—Melongena corona
  • five or six Florida Fighting Conchs—Strombus alatus
  • several Banded Tulips—Fasciolaria lilium hunteria
  • two Say’s Pear Whelks—Busycon spiratum pyruloides
  • five small Lightning Whelks—Busycon contrarium
  • numerous Eastern Nassas—Nassarius vibex
  • tiny Oyster Drills—Urosalpinx tampaensis
  • Marsh Periwinkles—Littorina irrorata
  • several Common American Augers---Terebra dislocata
  • Cross-barred Venus Clams—Chione cancellata
  • many Lettered Olives—Oliva sayana
  • Moon Snails—Neverita duplicata
Oh yes, there have been many other tasty treats for this guy as well. 


Then there were the half dozen Spruce Creek Melongenas—
Melongena sprucecreekensis gathered south of Daytona Beach at Spruce Creek in July.  By the middle of September, all six shells were empty!  Believe me—this is really a nifty way to clean your shells!!  To show that this ravenous mollusc is not a terribly picky eater, three of the invasive species of Asian Green Mussels---Perna viridis have also gone his way.

These are the molluscs on Horse Conch’s menu I’m able to recall.  There’s really no telling what might become the next part of his diet!  I’m wondering-----you don’t suppose that it just might be that True Tulip??

the Horse Conch just beginning to eat the last of my 6 Spruce Creek Melongenas, Melongena sprucecreekensis. A portion of the Melongena animal still shows in the picture. - September , 2006

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