Fun with Sea Shells / Sea Shells and Other Treasures
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I love to walk along the beach and collect shells. There are thousands of different sizes and shapes and colors. If I find a kind I've never seen before, I look it up in a book about shells to learn the name. Sometimes I find sand dollars, sea stars, or a sea urchin, which is pretty exciting, too. Click on the following picture buttons to see photographs of my favorites.

Urchins, Stars, and Sand Dollars Page Shells Page

It's fun to watch the creatures that live along the seashore. Pelicans are great fliers and sometimes dive right into the ocean to catch fish. Crabs walk sideways and try to hide a lot. You might see a dolphin, a sea turtle, or a ray. Keep watching. There's a lot going on.

Crabs Page Birds Page

The shells you see on the beach are what's left over when a mollusk dies or gets eaten by another creature. If you are really lucky, you might see some living mollusks. If there happens to be a tidal pool at the beach, or a rocky shoreline, or you can visit a mangrove forest, or you know how to snorkle, you just might see some mollusks in their natural habitat.
Mollusks come in many sizes and shapes and colors. There are five kinds of mollusks that live in the ocean: gastropods, bivalves, tusk shells, chitons, and cephalopods. These are described below. The ones whose shells you are most likely to see are gastropods and bivalves.
These animals are a lot like the snails that you might see in a garden, except these live in water. As they grow, a shell forms around their body. As they get bigger, the shell gets bigger. The shell is part of the animal.

Gastropods can scrunch up inside their shells when they feel threatened. A hard pad on their foot covers the opening of the shell to keep predators out. This pad is called an operculum. Look for this clue that the gastropod is still in his shell. When a gastropod wants to emerge from his shell, part of his body slides out, but he remains attached to his shell. Most gastropods have eyes and a mouth and one big "foot" that they use to move along. Some have a probiscis which looks something like the trunk of an elephant. It comes out of the mouth to grasp prey.

Gastropods have one shell. Usually, that shell grows in a spiral. The shell may look like a cap, a human ear, a toy top, a pear, a corkscrew, a spindle, a club, a barrel, an egg, or an irregular shape. Some eat bits of plant matter. Some eat other animals. View a page full of mollusk shells and links to information about each.

Bivalves have a shell in two parts that can open and close. They may be shaped like a discus, a fan, a triangle, a boat, a paddle, a heart, or have an irregular shape. They are also called filter feeders because they catch and eat tiny bits of food in the water. Clams and oysters are filter feeders. Some, like this scallop, may have lots of tiny eyes and sensory tentacles.

Scaphopods or tusk shells are small and look something like the tusk of an elephant or a walrus. They live in the sand or mud out from the shore. You are not likely to see them or find their shells on the beach.

Chitons are unusual because their shell is made in connected parts that allow it to roll up into a ball for protection. It can also curve its body to hold onto rounded surfaces.

Cephalopods don't look like other mollusks. This group includes the nautilus, which does have an external shell, and the cuttlefish, squid, and octopus, which do not. These mollusks eat other creatures. Instead of a single "foot", these creatures have long arms or tentacles.

Creatures like sea stars, sea urchins, and sand dollars (which are also urchins) are all part of a family called echinoderms.

Sand dollars are brownish in color and have tiny spines on them to help them get around. Sea urchins have spines, too. They also have little tube feet with suckers on the end mixed in among the spines. The tube feet are used to move around and to hold onto food. Instead of thin spines, some urchins have very thick spines.

When urchins die, the spines usually fall off and the remaining "shell" is called a test. A sea urchin test looks like a colorful pin cushion. The familiar white sand dollar tests found on the beach have been bleached by the sun.

Sea stars, commonly called starfish, may also have spines on their bodies, but they rely more on their arms to move around and capture prey. When a sea star dies, it's body is likely to retain its appearance.

2014, Jerry Jindrich. All rights reserved. Revised 1/25/2016.