How Are Seashells Created? A Marine Biologist Explains 7 Key Facts

Some sea animals, like snails, clams, and oysters, are mollusks. They have soft bodies and use a special part called the mantle to take minerals from the ocean water. This part builds a hard shell around their body, using a mineral called calcium carbonate. The mantle releases these minerals in layers:

• First, it makes a thin, tough outer layer for protection.
• Then, it adds middle layers that are hard and strong.
• Finally, it creates a smooth, shiny inner layer (sometimes called “mother-of-pearl”).

As the mollusk grows, more shell material is added by the mantle at the edges. This is how seashells are made bigger and thicker over time. In this blog, it will be explained how are seashells created? In nature, and many other fun facts too. Just keep reading….

What Are Seashells Made Of?

Seashells are mostly made from a mineral called calcium carbonate. This is the same material that is found in chalk and some types of rocks. A special part of the mollusk’s body, called the mantle, is used to collect calcium and other substances from the ocean water. Then, the shell is slowly built from these materials, layer by layer.

Lets know step by step…..

• The mantle releases proteins and calcium carbonate, which harden to form the shell like money cowrie shell.
• The ocean contains plenty of calcium (about 400 parts per million) that these animals can use.
• Most types of seashells are made with 2 or 3 layers. A thin outside layer is used for protection.
• A middle layer is made from calcium crystals. Sometimes, a shiny inside layer is added. This shiny layer is called mother-of-pearl.
• The shell grows bigger as the animal grows, making more space for its soft body inside.
• Most seashells are about 95-99% calcium carbonate with a small amount of protein.

Shells come in different thicknesses. Some, like angel wing shells, are very thin, while others, like giant clam shells, can be more than 8 inches thick. Some tropical shells can grow by 0.5mm every day in the right conditions. The shell is like a house or shield for the animal. It keeps the animal safe, stops it from drying out, and gives its muscles something to hold. When you are doing shell collecting on the beach, and find a beautiful shell, you chill, but a sea animal made this pretty shell from sea minerals.

Who Makes Seashells?

Seashells are made by sea animals like snails, clams, oysters, and scallops. These creatures have a special part called the mantle, which is responsible for building their shells. The mantle uses minerals from the ocean, especially calcium carbonate, to create the shell in multiple layers.

Over 85,000 types of mollusks are known to make shells. This process has been happening for about 540 million years, dating back to the Cambrian period. The oldest known shells are from this time. As the mollusk grows, its shell gets bigger, with new material added at the edges.

Each day, most mollusks add a new growth line to their shell, much like tree rings. These lines help scientists determine the age of the mollusk. Some clams can live over 100 years and keep adding to their shells as they age.

A seashell is made up of three main layers

1. The outer layer, called the periostracum, is made of protein. This layer can be rough or spiky to protect the shell. It also helps the shell resist breaking down in acidic water.
2. The middle layer is made up mostly of tiny crystals called calcite. These crystals form small prisms and can be up to 0.05mm thick, making the shell strong and durable.
3. The inside layer, known as nacre or mother-of-pearl, is smooth and shiny. This layer is made of tiny crystals called aragonite, arranged in thin sheets. It gives the shell its beautiful luster.

The mantle plays a key role in creating these layers. It produces special proteins that guide the crystals to grow in a specific pattern. Interestingly, just 5% of the proteins in the shell can make it 3,000 times stronger than pure calcium carbonate.

Making and maintaining the shell takes a lot of energy. Mollusks can use up to 30% of their total energy just to build and keep their shells strong and intact.

The patterns and colors of seashells are unique to each mollusk. The colors are created by special cells in the mantle that produce pigments. Some common pigments include melanin (which gives brown or black colors), porphyrins (which create red or pink hues), and carotenoids (responsible for yellow or orange colors).

These beautiful and strong shells can last for thousands of years, even after the mollusk has died, providing a glimpse into the fascinating world of sea creatures and their natural creations.

Suggested Read: What Are the Three Seashells? (Demolition Man’s Funniest Mystery Explained)

How Are Seashells Created Step by Step?

1. When a mollusk (like a snail or clam) is born, it already has a tiny, soft shell to protect its body. This first shell is called the protoconch or prodissoconch, and it forms when the mollusk is still a baby. The shell is usually only 0.1-0.5mm in size. In many species, the shell starts to form inside an egg, where the baby mollusk makes its first shell using special cells.

“Did you know that some seashells can grow by 0.5mm every day in warm waters?”

2. The mollusk’s mantle, a special part of its body, takes minerals from the seawater, mostly calcium carbonate, and uses them to build and grow the shell. They are also among the good macro decomposers of the ocean. The mantle has millions of special cells that bring in calcium and other chemicals from the water to help create the shell. For every gram of shell made, a mollusk has to process about 1-2 liters of seawater to get enough calcium.

3. The minerals form crystals that make the shell strong and protective the mollusk grows, the shell gets bigger by adding new layers at the edges. The shell has three main layers where this process happens.

• The outer layer, called the periostracum, is made of a protein that helps protect the shell from damage and provides a base for the minerals to stick to.
• The middle layer, called the prismatic layer, has calcite crystals arranged in columns. These crystals help make the shell strong and able to withstand pressure.
• The inner layer, called the nacreous layer, has aragonite crystals arranged like bricks and mortar. This makes the shell 3,000 times stronger against breaking than just pure calcium carbonate.

4. The mantle controls the shell’s shape, color, and pattern by making special proteins and minerals. These create the unique look of each shell. Special cells in the mantle add color, making patterns appear. The shell grows at different speeds, about 0.01-0.5mm per day. Mollusks grow shells faster in warm water (25°C) than in cold water (10°C).

5. When the mollusk dies, its hard shell stays behind and often washes up on beaches for us to find and admire. Shells can last for hundreds to thousands of years, depending on water and how they’re buried. Empty shells become homes for small creatures and slowly break down, sending calcium back into the ocean to start the cycle again.. The calcium in shells helps store about 1.8 billion tons of carbon in the ocean every year.

 How Do Seashells Get Their Colors and Patterns?

Seashells get their colors and patterns from pigments made by the mollusk’s mantle, the part of the animal that builds the shell. Special cells chromatophores in the mantle make the pigments and add them to the shell as it grows, like how a printer makes a design line by line.

Scientists have identified the main pigment families in seashells:

• Melanins: Create brown, black, and gray colors; the most common and stable shell pigments
• Porphyrins: Produce red, pink, and purple hues; found in many tropical species
• Carotenoids: Generate yellow, orange, and sometimes red colors; often derived from the mollusk’s diet
• Polyenes: Create vibrant blues and greens; relatively rare in shells (found in only about 10% of species)

The patterns on seashells, like stripes or dots, are made by pigments in the mollusk’s mantle. These patterns form because of special chemicals that work together in the mantle. Each mollusk creates its own unique pattern, so no two shells are exactly the same.

Factors influence shell colors and patterns of Seashells

• Genetics: The mollusk’s DNA determines the types of pigments and pattern styles it can produce. Studies show that about 30-50 genes control shell patterning in most species.
• Age: Patterns can change or become more complex as the mollusk grows. Young shells often show simpler patterns, while mature shells display more elaborate designs.
• The color and pattern of seashells can change depending on where they live. Shells from warm tropical waters are usually more colorful than those from cold waters. Some shells also change color with the seasons, which can help scientists tell how old they are.The colors and patterns can help the animal hide from enemies or blend into its home. For example, shells on sandy beaches are often light-colored with spots, while shells on rocky shores look different.After the animal dies, the shell’s color fades. Some colors last a long time, like browns, while others fade faster, like yellows and oranges. That’s why shells found on the beach might look lighter than ones still on the animal

Why Do Seashells Have Different Shapes?

Seashells come in different shapes, and each shape helps the animal live in its home. There are over 50,000 types of mollusks, and scientists have found 7 main shell shapes: coiled, spiral, cone, bivalve, tube, cap, and multivalve. Each shape helps the mollusk stay safe, find food, and live where it does.

For example, some seashells are flat because the mollusk digs into the sand. Others are spiral-shaped to make the shell strong and easy to carry as the animal grows. Here’s how these shapes help:different shapes help:

• Bivalves (like clams and oysters): These shells have two parts connected by a hinge. This helps them filter water for food while staying protected. Some burrowing bivalves have smooth, streamlined shells that reduce drag by up to 60%.

• Gastropods (like snails and conches): Their spiral shells are strong and light, saving energy. The spiral shape follows a special pattern called the Fibonacci sequence, which helps the shell grow in a balanced way. These snails only use 3-5% of their energy to carry their shells.

Cephalopods, like the nautilus, have spiral shells with chambers inside. These chambers help the nautilus control its position in the water. It can float up and down by changing the amount of gas and water in the chambers, without having to swim.

The shape of a seashell is also influenced by how the mollusk’s mantle grows. The mantle builds the shell by adding material in a specific way, and scientists have found that the shape of the shell follows certain patterns. For example, many coiled shells grow in a spiral, with each new layer getting a little bigger than the last one.

Sometimes, parts of the shell grow unevenly, creating spines or bumps. These features can help protect the mollusk or help it blend into its environment. Spines can increase a shell’s effective size by up to 300%, deterring predators with smaller mouthsRidges and ribs can strengthen a shell by 40-60% against crushing predators

Some species have very thick shells that can handle pressure up to 30 megapascals, which is like being 3,000 meters underwater. Where they live affects the shell’s shape too. Shells from places with strong waves are usually 30-50% thicker and more compact than those from calm waters.

The temperature of the water also matters. In cold waters, shells tend to be thinner and more fragile because calcium carbonate doesn’t dissolve as easily as in warm water. Seashells have changed over millions of years to help each animal live in its environment. This helps them stay safe from predators and survive in different ocean conditions.

Can Seashells Tell Us What the Mollusks Eat?

Yes, seashells can sometimes tell us what the mollusks ate. The diet of a mollusk affects how fast its shell grows and can even influence the shell’s color and pattern. Researchers have developed several methods to analyze shells for dietary information:

Scientists can learn about a mollusk’s diet by studying the chemical markers in its shell, like carbon-13 and nitrogen-15. These markers show what the mollusk has been eating over its life. For example, herbivores usually have different carbon isotope levels than carnivores. These chemical signals act as a record of the mollusk’s feeding history.

Shell growth bands also give clues about the mollusk’s diet. Mollusks that filter food from water, such as clams and oysters, have shells that grow in regular patterns with evenly spaced bands. On the other hand, carnivorous mollusks show irregular growth, with faster shell growth after feeding.

Specific shell features can indicate feeding strategies:

• Carnivorous cone snails have a notch in their shell for extending their venomous harpoon
• Oyster drills have a specialized boring organ that leaves a perfectly round hole in prey shells
• Filter-feeding scallops have lightweight, fan-shaped shells optimized for swimming to escape predators
• Herbivorous limpets develop thicker, more abrasion-resistant shells from constantly grazing on rocky surfaces

The color of a mollusk’s shell can show what it eats. For example, mollusks that eat algae with lots of carotenoids (the pigments that give algae their color) can have yellow, orange, or red shells. Some herbivores can even transfer up to 15% of the pigments they consume directly into their shells.

For older shells, like fossils, scientists can examine wear patterns on the opening of the shell to understand the mollusk’s diet. Fine scratches might show the animal scraped algae from rocks, while impact marks might indicate it crushed harder prey.

By studying seashells, scientists can learn about what the mollusk ate and how its diet changed over time. They can even tell if the animal went through times when it didn’t have enough food. Seashells can show if the mollusk was a filter feeder, herbivore, or predator. Modern tools can find small traces of food in the shell, helping scientists understand the ancient ocean food chains.

In simple terms, seashells can tell us a lot about the life and eating habits of the mollusk that made them.

How Do Living Creatures Use Shells?

Living creatures use shells in several important ways:

Shells help animals like clams, snails, and oysters stay safe from predators. They act like strong armor. Some shells, like the giant triton snail, can handle a lot of pressure, up to 3,000 pounds! Some deep-sea mollusks have even stronger shells made with special minerals. The shell also protects the mollusk’s soft body, keeping it safe from injury and harsh conditions. It’s like a little house for the animal.

Some shells have special layers that help them resist cracks and damage. The inside layer, called mother-of-pearl, is stronger than the outside. Shells help mollusks stay safe from things like big temperature changes or drying out when the tide goes down. Some animals, like hermit crabs, don’t make their own shells. They find and move into empty shells left by other mollusks. This keeps them safe while they grow.

Hermit crabs often “share” shells, so several crabs can live in the same shell over time. About 15-20% of empty shells in shallow waters are used by hermit crabs. Sometimes, many crabs will switch to a bigger shell when one becomes available.Some animals let algae or plants grow on their shells to help them blend in with their surroundings, making it harder for predators to spot them. Studies show this camouflage can reduce the chance of being eaten by 30-70%.

Sea turtles often carry over 100 species of algae and small creatures on their shells, creating little ecosystems. Other animals, like small octopuses, use shells as shelters or shields. The coconut octopus is known for carrying coconut shells as portable homes. It’s the first invertebrate to use tools.

Environmental adaptation

Shells help animals live in different places. Deep-sea scallops have lighter shells than those in shallow water. Mollusks living in acidic water, like around hydrothermal vents, make special shells that don’t dissolve in the acid.

Breeding & reproduction

Some mollusks, like the nautilus, use their shells to help them move up and down in the water to find mates. Female argonaut octopuses make thin shells to hold up to 200,000 eggs. The shells protect the eggs and give them the right amount of oxygen.

Bonus: How to Create Seashell Art

Collect and Clean Your Seashells

1. Gather seashells from the beaches you like or craft stores.
2. Clean seashells by rinsing with soapy water and letting them dry.
3. For extra cleaning, soak shells in a mix of water and hydrogen peroxide (3% solution) to remove dirt and odors. Research shows that a 24-hour soak can eliminate 99% of bacteria and organic matter.
4. For stubborn debris, a soft toothbrush can safely clean shell surfaces without causing damage. Marine biologists recommend avoiding bleach, as it can degrade the shell’s natural colors by up to 30-40%.

Choose Your Project

Seashell Wall Art

You can make cool shapes like hearts, stars, or waves by gluing shells onto a wooden board or canvas. Dark backgrounds make light shells stand out, while light backgrounds work better for dark or colorful shells. Artists say using shells at different heights looks better than making them all flat.

Seashell Picture Frames

You can decorate simple picture frames by gluing shells around the edges for a beachy look. Frames with shells held in place by glue and a groove last 3-4 times longer than those with glue alone.

Seashell Jewelry

You can make necklaces, bracelets, or earrings by drilling small holes in shells and adding string or wire. Use a diamond-tipped drill bit at low speeds to avoid cracking the shells. Keeping the shells wet while drilling helps prevent breakage. After making the jewelry, coat it with clear nail polish or sealant to make it last longer.

Seashell Resin Art

You can put shells in clear resin to make coasters, paperweights, or other decorations. Use epoxy resin with UV protection to keep it from turning yellow for 5-10 years. Pour the resin in layers, letting each layer set a little before adding more shells and resin.

4 Expert Tips for Success

1. First, plan your design by laying out the shells before gluing them down. Professional shell artists often take a photo of their layout to help them when they start gluing.
2. Use strong glue like E6000 or marine epoxy because it lasts 5-10 years and is waterproof. Hot glue, on the other hand, usually lasts only 1-2 years before the shells might start to come off.

3. Mix different sizes and shapes of shells to make the design look more natural. Studies show that using at least 3-5 different types of shells makes the art look 40% more appealing than using just one type.

4. You can also add paint, beads, or glitter for extra decoration. Acrylic paint with clear sealant makes bright colors without damaging the shells. In the Philippines, shell artists use natural dyes from berries and plants to color shells safely.

Kid-Friendly Projects

Simple shell crafts, like making collages or decorating jars and boxes, are great for kids.

Always watch them when using glue guns or sharp tools. Studies show that kids aged 5-10 who do shell art improve their fine motor skills by 15-20% in 3 months.

Making seashell art is a fun way to turn beach treasures into special decorations for your home! Shell art has been around for over 100,000 years, Archaeologists found shell beads in Morocco that are some of the oldest decorations ever made.

How Are Seashells Formed in Nature & the Ocean?

Seashells are made by a natural process called biomineralization, which can take weeks to years. Mollusks like snails, clams, and oysters create their shells using special cells in a part of their body called the mantle.

Mantle Secretion

The mantle, which is the tissue under the shell, releases proteins and minerals to form the shell. It’s like laying down steel (protein) and pouring concrete (minerals) over it.

Calcium Carbonate Formation

Mollusks get calcium and carbonate from seawater. They combine these to make calcium carbonate, which sticks to the protein frame, kind of like how cement sticks around steel bars.

Crystal Formation

The calcium carbonate can form two types of crystals: calcite and aragonite. The middle layer of the shell makes calcite crystals, which help make it tough. The innermost layer, called nacre or mother-of-pearl, is made of protein and calcium carbonate. It looks and feels different because the mantle uses different proteins to make a special crystal called aragonite.

Shell Growth

Seashells grow from the bottom up by adding material at the margins. As the animal grows, its shell must grow along with it, resulting in growth rings that allow us to measure a mollusk’s age. The shell grows as the mollusk grows, by excreting proteins and minerals from its mantle.

Ocean Minerals

Mollusks harvest calcium ions and carbonate ions from seawater to build their shells.

Ocean Acidity

When the ocean gets more carbon dioxide, it becomes more acidic. This makes it harder for animals like mollusks to get the materials they need to make their shells. When the animal dies, the shell is gradually pounded against the rocks and sand, breaking down over time and becoming part of the sand. White beaches have sand made almost entirely of tiny bits of shells.

FAQs

Conclusion

Now you know the answer to how are seashells created. These beautiful ocean treasures form through natural processes guided by marine life. Understanding their creation helps us appreciate the wonders of the sea and the delicate balance of marine ecosystems.