How to identify collected shells
You’ve enjoyed a VERY early morning walk on the beach at low tide, experienced the joy of watching the birth of a new day as the sun appeared on the horizon, and wandered the beach in relative solitude. Only the serious shell collectors or bird watchers give up coffee and donuts for this appointment with nature. Your next appointment was with a bleach bottle, brushes, dental tools and mineral oil. Now it’s time to become a “book worm.”
Your beach treasures are scattered across the kitchen table or hobby room table if you are lucky enough to own such a space. Your curiosity is peaked. What are the names of the shells you’ve collected?
By now you’ve learned that shells are the lifeless, hard, outer covering of the soft critters that once lived within them. For most mollusks, the shell provides both support and protection.
Scientific nomenclature is kind of like looking at your family tree. The binomial method of giving a species a name is similar to the way we name people. The generic name is like our last names of Jones or Smith. The species name is like our first names of Mary or Joe.
Mollusks and other animals have both common and scientific names. The common names get established by habit or repeated usage. However, common names lead to confusion or misinterpretation.
The practice of giving species a two-part name began with Carl von Linn. Scientific names, although complex, are universal. The first part of the name represents the genus and the second part of the name is a specific ending or epithet.
It is believed that well over 100,000 mollusks are in existence. Mollusks are divided into seven classes:
n Aplacophora more than 250 species of marine, shell-less, wormlike, bilaterally symmetrical animals.
n Monoplacophora about a dozen species first discovered in the 1950s have a capped-shaped, limpet-like shell and live in great depths.
n Poplyplacophora – chitons about 800 marine species that have a shell of eight, usually overlapping plates.
n Scaphopoda – tusk shells about 350 marine species bilaterally symmetrical and have elongate, tubular, tapering shells that are open on both ends.
n Cephalopoda – include squid, octopus, cuttlefish, and nautilus – 600-650 marine species that are predators or scavengers.
n Bivalvia two halves connected by a flexible ligament more than 10,000 living marine and freshwater species.
n Gastropoda single-valve shell which is usually spirally coiled – more than 60,000 species – marine, freshwater and terrestrial habitats.
Let’s look at a couple of examples. A gastropod frequently found on Sanibel beaches is the lightning whelk. It is generally found in shallow water. Lightning whelk is the common name. The class for this shell is Gastropoda. The genus is Busycon. Busycon have been endemic to the southeastern United States for over 60 million years. So, the genus for the lightning whelk is Busycon and the specific ending or epithet is sinistrum. Therefore, the scientific name for the lightning whelk is Busycon sinistrum.
A bivalve that dots the beaches of Sanibel is the calico scallop. Worldwide there are over 50 genera of scallops. The calico scallop is commonly found in 6-8 feet of water. The upper valve has colorful mixed shades and the lower valve is whitish with flecks of color. The class for this shell is bivalvia. The common name is calico scallop. The genus is Argopecten and the specific ending or epithet is gibbus, so the scientific name is Argopecten gibbus.
There are a few tools you might find helpful as you begin the process of identification. One of the best sources of information can be found on The Bailey-Matthews Shell Museum website, www.shellmuseum.org. Just select Southwest Florida Shells on the home page menu.
The Museum has produced a “water proof” guide for the shells of Southwest Florida. It is available in the Museum gift shop for $7.95 plus tax. This is great for taking to the beach with you. The three shell guides most often recommended are Peterson’s First Guide To Shells of North America, Seashells of North America by R. Tucker Abbott and the National Audubon Society Field Guide To Seashore Creatures. All of these resources are available in the Museum Store.