Shell (zoology) facts for kids

A display of shells of marine molluscs, including abalone, scallop, and blue mussel

A shell is a tough, hard outer covering that protects many different animals. Think of it like a natural suit of armor! Over time, many animals have developed shells, including molluscs (like snails and clams), sea urchins, crustaceans (like crabs and lobsters), turtles, tortoises, and even armadillos.

Amazing Animal Shells

Seashells: Nature's Treasures

When you think of shells, you probably picture seashells! These are the most common type of shell you'll find, both in the ocean and in shops. Most seashells are made from a material called calcium carbonate. This is the same stuff that chalk and limestone are made of. It can be found in different forms, like nacre, which is also known as mother-of-pearl. This is the shiny, colorful layer you see inside some shells.

But not all shells are made of calcium carbonate. Some animals have shells made from other materials. For example, insects and crabs have shells made of chitin. Other animals, like turtles, have shells made of bone and cartilage. Some tiny sea creatures even have shells made of silica, which is like glass!

How Animals Use Shells

Shells are super important for the animals that have them. They offer protection from predators, like a shield. They also help animals survive in harsh environments, protecting them from drying out or from strong currents. For example, a snail can pull itself completely inside its shell when it feels threatened.

Shells and People

For a long time, people have loved shells! They are beautiful and come in so many shapes and colors. People have used shells for all sorts of decorations. They turn them into beads, buttons, brooches, rings, and even hair combs.

Tiny pieces of colorful or shiny shell are often used to make amazing mosaics and inlay designs. These can decorate bigger items like boxes or furniture. You might also see many whole seashells arranged to create patterns in special decorated caves called grottoes.

When you walk along a beach, you might find many different kinds of shells. These are often the exoskeletons (outer skeletons) of sea animals that have died. People who enjoy walking on beaches and collecting things are called beachcombers. They often look for these natural treasures. However, usually only the shells from molluscs are called "seashells."

Main Kinds of Shell-Forming Molluscs

Most molluscs that form shells belong to two main groups:

• Gastropoda: These are often called univalves, meaning they have one shell. Snails, both land snails and sea snails, are gastropods.
• Bivalvia: These are called bivalves, meaning they have two shells that are hinged together. Clams, oysters, and scallops are all bivalves.

Gallery

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  The marine gastropod Cypraea chinensis, also known as the Chinese Cowry, showing its mantle (a soft body part) partly out of its shell.

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  The giant clam (Tridacna gigas) is the largest bivalve in the world.

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  Tonicella lineata, the "Lined chiton", found in the eastern Pacific Ocean. Chitons are another type of mollusc with several shell plates.

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  The white-lipped snail (Cepaea hortensis) is a common land snail.