By Tom Baird
When the economy is bad and legislatures don’t have much money to spend, we often see a lot of Feel Good bills introduced. They don’t cost any money, but look like the legislators are doing something. One category of Feel Good bills is designations of state symbols like State Bird, State Mammal, State Fungus, etc. For instance, the State Gem of Florida is the Moonstone, which does not even occur in Florida. It was passed in the wake of the Apollo program and is symbolic of Florida’s role in the moon landings.
One designation that the legislators got right is the State Shell. The Horse Conch (Triplofusus giganteus, formally Pleuroploca gigantea) is the largest snail in North America and it is a resident of St. Joseph Bay. Individuals can attain a length of two feet, also making it one of the largest snails in the world. Horse Conchs are predators and are large enough to prey of other large gastropods in the bay like the Left-handed or Lightening Whelks. Horse Conchs prefer sandy bottoms and smaller specimens can be seen hunting in shallow water. The Horse Conch is found all around the Florida peninsula, but is most abundant on the southwest coast around Naples and Sanibel Island, and is rarely found in the Big Bend part of the coast with its abundance of grass flats.
There is evidence that Horse Conchs were much more numerous in our bay. The Indian middens on the shore and islands of the bay all have weathering Horse Conch shells. Some of these are truly gigantic. In other parts of Florida Indians utilized Horse Conch shells to fashion tools. Here, it appears that they mainly used the shells of Left-handed Whelks for tool making and harvested the Horse Conchs for food. Nevertheless, there are fewer Horse Conch shells in the Indian middens than the Whelks. This could either reflect the relative abundance of whelks to conchs, or possibly the Indians just preferred the meat of the Left-handed Whelk. We would also expect the prey species (Whelks) to be more numerous than the predators (Conchs).
Numerous factors account for the decline in the Horse Conch population, but one is shell collecting. Oral accounts tell of past collecting activities that took large numbers of live Horse Conch shells. If collecting, take only empty shells, and leave even small empty conch shells for the Hermit Crabs. Shell collecting hurts not only the conchs but other species as well. It is illegal to collect live shells without a license. Nevertheless, there remain some very large Horse Conch specimens in the bay, and their egg masses are occasionally seen. Unlike the coiled egg masses of the Lightening Whelks, Horse Conch egg masses are in a twisted clump with each egg looking somewhat like a flattened bugle.
You may also find the large operculum or “trap door” of a Horse Conch when snorkeling. This is the rich, dark brown, horn-like material that the conch uses to close the opening of its shell. If you have ever picked a live Horse Conch you know that the body is a bright reddish-orange color that retracts into a dark maroon shell. It is a truly handsome marine snail.
Far more numerous and easy to see are the Crown Conchs (Melongena corona). Crown conchs will reach a maximum size of five inches, but smaller specimens are more common. Unlike Horse Conchs, Crown Conchs are scavengers. After cleaning your scallops in shallow water, you’ll soon have fish, crabs, and a slow motion procession of Crown Conchs moving in to take advantage of the spoils. Crown Conchs also invade baited traps, and can sometimes be seen in mass feeding on a dead Horseshoe Crab. Crown Conch shells are also found in Indian middens and the dark meat is edible although a bit chewy.
Crown conchs get their name from the spires around the axial ribs. Turned point upward, the spikes look like a monarch’s crown. There is a lot of variability in Crown Conchs. Some have long, curved, hollow spikes; others have only short nubs. There is also a good amount of color variation in live specimens. Nevertheless, most have bands of brown, tan, and maroon circling the shell and are quite pretty. Others have very pale bands. These variations are the result of genetic differences in both individuals, as well as populations, and also diet. Crown conchs live around mangroves and salt marshes, but are always found in shallow, quiet bay waters or estuaries. Hermit crabs also prize empty Crown Conch shells, so it is best to collect the empty shells on the beach and not in the bay.
Despite the common names we use, Crown Conchs are actually Whelks, and Horse Conchs are actually Spindle Shells and are not true conchs. They are more closely related to Tulip shells. By whatever names we call them, the little Crown Conchs and the massive Horse Conchs are part of the rich diversity of life in St. Joseph Bay. The conditions that have made them flourish here in the past must be guarded so that their numbers continue.
Tom Baird has been a fisheries biologist, high school and community college teacher (oceanography and microbiology), director of a science and environmental center, teacher of science and principal in Pinellas County as well as an educational consultant. He retired from the Florida Department of Education and he and his wife divide their time between Tallahassee and Cape San Blas.