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various seashells

A Brief Guide to the Classification of Conches and Sea Shells


How do we decode the enchanting things we find while strolling the beach...

No matter where you are in the world, every beach offers visitors rewards. The fact is that sea shells, conches, and the remains of other marine animals, though shipwrecked on the seashore, retain a very special magic. Once part of the living beings inadvertently inhabiting the oceans, as corpses, few can resist collecting them. This is perhaps because of their worn and polished qualities, or for their strange shapes and faint colors. But these skeletons can’t help but fascinate us and invite us to know a little more about them, about their classifications and their former owners. It’s an encounter with the life that blooms beneath the sea.

There are many types of graphic guides (like this one) to give you more information about the shells found on the beaches of the world. This short guide, courtesy of Atlas Obscura, offers expert advice on invertebrate sea animals and on finding, recognizing and classifying them…

Identify the Habitat
Are you facing a body of fresh or salt water? Are there strong currents or is the water still? The answers to these questions will give you clues as to the origins and types of animals you can find there. Sandy beaches, for example, are often home to bivalves, animals of the Mollusca phylum, and who have two lateral valves. They normally live buried beneath the sand. Rocky beaches, on the other hand, are home to chitons (or “sea cradles”), snails, and limpets —all of them capable of adhering themselves to the surface of rocks.

Count the Valves
The number of any marine animal’s valves gives us many clues about the species, so it’s important to count them. Among the most common, gastropods have a single shell and bivalves have two. For their part, the shells of chitons, or sea cradles, have eight linked parts.

Note the Color
In general, tropical shells will have brighter colors than those of animals from colder waters. In particular, those from intertidal zones in regions like Alaska, Siberia, Canada, and Greenland, all have dark and sometimes black shells in order to conserve heat. The tone of a shell can also give information about the depth of the waters and the region from which it came.

Shells can also vary in coloration despite being from the same species. There are some which change their appearance over time and lose their color with age, as is the case with the Icelandic clam (Arctica islandica), which, in its youth, has brown and white patterns; these disappear as the clam ages. Usually, the older a shell is, the less striking is its appearance.

Sea shells on the beach


Observe Ornamentation
Some shells are simply unmistakable for their beauty. The queen conch (Lobatus gigas) with its pearly lip and wavy edges, and the shell of the spider conch (Lambis lambis) with its pointed protuberances, are but two examples of how a striking style can be an indicator of age. The queen conch, for instance, stops being rolled by the waves when it reaches sexual maturity, after which its outer lip will thicken.

The size of the shell, though, does not necessarily denote age. For example, the giant clam (Tridacna gigas) reaches an enormous size from a young age, and its shells can weigh more than 200 kilograms. Some smaller clams may even grow up to one centimeter a month under the right conditions. On the other hand, an Icelandic clam specimen found recently, and named “Ming,” measures five centimeters and is estimated to have lived for between 400 and 500 years.

Sea Conchas


Some recommendations for finding sea shells

  1. 1. Choose a good time. There will always be opportunities for finding conches and shells when the tide is low. A low tide allows for better visibility of what’s recently been expelled by the sea and it’s much easier to find shells than when they’re under the waves. Before setting out on your search, it’s also good to check a map of sea currents, as these will indicate in which regions of a beach you’re more likely to find shells. Storms can also send many marine animals to the beaches, especially during the winter.
  2. Bring the right tools. Many enthusiastic collectors use them when searching. Tools can include a magnifying glass and knee pads to be able to kneel more comfortably, especially if you’re looking for small shells. If not, a bucket, or bag, a small metal shovel and a sieve will suffice.
  3. Check out the area. You can divide it into a grid before you start searching.
  4. Take some with you. After all, they’re some of the most beautiful things in the world.



Images: 1) Creative Commons 2) Leonardo Aguiar – Flickr 3) H. Zell – Creative Commons

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