What the Shell? Identifying Seashells

By Sarah Rosenbaum

When I first joined the shelling world, like many others, I had just found myself in search of a new career path due to the pandemic. I came across a post online seeking part time help as a shell guide for Treasure Seekers Shell Tours in Marco Island, Florida.

Being a natural born Floridian, many people find it odd that I rarely went to the beach as a child. My parents didn’t care for the messy sand and they weren’t fans of seafood either so boating was not one of our pastimes. To be honest, I didn’t know shelling was something people pointedly did with their time.

So when I came to The Ten Thousand Islands National Wildlife Refuge on a shelling tour for the first time, I was blown away to find out just how many varieties and details there are in the shells found on the barrier islands.

As I mentioned, I knew next to nothing about shells when I started, so I had to learn fast. The great thing about learning is the more interesting the subject, the easier it is to absorb. The more I learned about creation and all the intricate details in it, the more I wanted to learn. I soaked in as much as I could so I could share with all of our guests and anyone who would listen about the wonders in the ocean.

Later on, I went back to school and became a Florida Master Naturalist through the University of Florida. The courses proved very helpful for shelling in that, the more you know about the coastal environment systems, the more you’ll know where to look for certain species. 

The first thing to learn when identifying shells are the basic anatomy terms. Anyone can describe a pattern and maybe even a texture. But how would you search online for a shell in a shape you can’t describe? Let’s talk about some terms that might help you.

Bivalve or Gastropod

First of all, you’ll want to determine if the shell is a bivalve or a gastropod.

Webster defines bivalve as “Any of a class (Bivalvia synonym Pelecypoda) of typically marine mollusks (such as clams, oysters, or scallops) that have a two-valved hinged shell, are usually filter feeders, and lack a distinct head.” 

Bivalves are often broken apart at the hinge before they wash ashore, so you may only find one half. When whole, they will have two matching sides (valves) attached on one end.

Gastropod is defined as “Any of a large class (Gastropoda) of mollusks (such as snails and slugs) usually with a univalve shell or none and a distinct head bearing sensory organs.” 

In simple terms, a gastropod is a univalve (one part) shell that usually spirals on one end with an open “tail” on the other, for example, conchs, and whelks. In some cases, such as cowries and limpets, gastropods are singular domed shells with a large opening where the head and foot of the mollusk may emerge.

Seashell Terms

The following are some other definitions to help you describe shells you may be trying to identify:

Whorl: One of the turns of a univalve shell.

Spire: The inner or upper part of a spiral gastropod shell consisting of all the whorls except the whorl in contact with the body.

Sculpture: Impressed or raised markings or a pattern of such, especially on a plant or animal part.

Aperture: An opening or open space.

Radial: Developing uniformly around a central axis.

Mantle: Soft, fleshy body wall that creates the calcified shell and surrounds the internal organs. Connected to the mantle is the foot of the mollusk used for locomotion.

Columella: The central column or axis of a spiral univalve shell.

Unique Characteristics

Some shells have very distinctive spikes, color patterns, or shapes that make identification simpler. Think also to look at whether the shell coils to the left or right. There are far fewer shells that spiral to the left (for example the lightning whelk) in the world than to the right so this may help narrow it down for you.

National Shell Museum App

When trying to identify a shell, the Internet is an obvious resource. The best website I’ve found is the Bailey-Matthews National Shell Museum and mobile phone app. The museum has an extensive electronic library with detailed descriptions of species found all around the world, especially in Florida where it is located. The descriptions include the length of the shell, whether it’s dense and heavy versus thin and fragile, how many whorls the spire features, how many ribs are on each whorl, the shape of the aperture and any other pertinent details to describe the shell in question. Photos of each shell are also included.

Online Resources

I have also found posting clear photos on social media helpful if you’re unsure of a shell’s identification. When I took on a job as a shell guide, I joined beachcombing and shelling Facebook groups to see what other people were sharing and asking questions about. Reading through comments where other ocean lovers could discuss, compare, and contrast shells was extremely educational.

Books and More 

Books with photos are also very helpful. At Treasures Seekers Shell Tours, we use Florida’s Living Beaches by Blair and Dawn Witherington as a training guide for our shell guides. This book can be found in nearly all the shell shops in Southwest Florida. This book is particularly helpful because of the brief yet rich descriptions of each shell, along with a clear and detailed photo of the shell in question. Books, websites, blogs, hobby groups, and social media platforms are all excellent resources and can almost always be applicable to your local shores.

The more I’ve learned, the more I’ve come to realize there is an endless amount of information out there and though I can’t learn it all, I can try! I encourage you to keep learning, no matter how old you are or what stage of life you’re in. Keep asking questions and keep discovering.

All photos courtesy of Sarah Rosenbaum.

This article appeared in the Beachcombing Magazine January/February 2023 issue.

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