Oyster Demonstration

Use a demonstration to show how oysters filter dirty water:

Materials needed

Oyster reef
Calvert Marine Museum

1 Gallon size Motts bottle filled with tap water

1 Large clear bowl

Oregano (to represent algae)

Dried onion (to represent detritus)

Peppercorn (to represent sediment)

4 Coffee filters


Hold up the Motts bottle filled with clean water. Show children how clean and clear it is. Tell them it will represent water in the bay or river.

Making oysters

Ask students if they think sea animals would like living in the clean and clear water.

Next, hold up each spice bottle, take off the lid and add one spoonful to the Motts bottle, explaining each time that you are adding algae (tiny plants that live in the water), detritus (tiny bits of broken down plants and animal waste), and sediment (tiny bits of broken down rocks).

After each spoonful, hold the bottle up and show how dirty and mucky the water is getting.

Ask children if they think sea animals will be able to breathe well in the dirty water.

Filter Water Like the Oysters

Ask students if sunlight will be able to reach the sea animals and underwater plants. Most living things need sunlight and oxygen to survive.

Ahead of time, line the strainer with a coffee filter and add three “oysters” made out of the coffee filters. You can find the instructions for the Easy Oyster Craft here.

Place the strainer over the clear bowl.

Lift up the oysters made from coffee filters and explain that they will filter the water similar to real oysters in the bays and rivers.

Ask the children what they think will happen when you pour the dirty water over the “oysters”. Will the water be clean after it goes through? Why? How?

Oyster Demonstration

Pour the water slowly over the filters.

Note: If you would like some of the debris to get through, you can remove the filter that lines the strainer.

Once the bowl is halfway full, hold the bowl up in the air so all can see.

Ask the children if the water is cleaner after going through the filters. Why? How? Will sea animals be able to breathe better in water with oysters?

Oysters are featured in my book about sea animals cleaning the Chesapeake Bay, Olly the Oyster Cleans the Bay. Watch the book trailer below.

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