๐Ÿ“˜ CodingMarble Learn

Project: Sealed Ecosphere Bottle

A sealed ecosphere bottle is a tiny closed ecosystem. Plants use light to make food and oxygen. Animals use oxygen and food and give out carbon dioxide. Microbes in the soil recycle waste. Only light enters. If plants, animals and light are in balance, the bottle can stay alive for weeks or months.

๐ŸŽฌ Step-by-step story

  1. Here is an empty clear bottle. We will build a small world inside it. It must have everything its living things need, because we will close it.
  2. First, layers. A layer of gravel lets extra water drain. Soil on top holds roots and tiny microbes that recycle waste.
  3. Add water and plants. Plants make food and oxygen when light falls on them. They are the producers.
  4. Add a few small animals, like pond snails. Animals eat plants, use oxygen and give out carbon dioxide. Count them: few is safer than many.
  5. Close the lid and put the bottle in bright, but not hot, light. Blue oxygen rises from plants, grey carbon dioxide returns from animals. Only light comes in. Everything else goes round and round.
  6. Free play: change the light and the number of animals. Find the balance, and see what breaks when there is too little light or too many animals.

Tip: drag the 3D scene to turn it. Use two fingers to zoom.

๐Ÿค” Common doubts, cleared

Where does the oxygen come from if the bottle is closed?

From the plants. They make oxygen when light falls on them.

Why is gravel at the bottom?

It lets extra water drain so the soil does not turn sour and roots can breathe.

Why only a few animals?

Animals use oxygen. With many animals, oxygen runs out faster than the plants can make it.

Why is direct hot sun bad?

It heats the water, which holds less oxygen, and stresses the animals.

What do microbes in the soil do?

They break waste into nutrients that plants can use again.

What if there is no light?

Plants cannot make food or oxygen, so the whole cycle slows and stops.

Choosing organisms and materials

You need a clear bottle or jar with a lid, gravel or pebbles, soil (not fertiliser-rich), clean water that has stood for a day (so chlorine can escape), a few water plants (like Hydrilla or Vallisneria), and 2 or 3 small pond snails or tiny fish. Pick organisms from the same kind of place, and use few animals compared with plants. Avoid dangerous or protected species, and return organisms to their natural place when the project ends.

Building a balanced bottle

  1. Wash the bottle without soap.
  2. Add a 2 cm layer of gravel, then 3โ€“4 cm of soil.
  3. Pour in water slowly until the bottle is about three-quarters full.
  4. Plant water plants firmly in the soil.
  5. Add the animals last, gently.
  6. Close the lid and place the bottle in bright, indirect light, away from direct hot sun.

Why it works: plants make food and oxygen by photosynthesis; animals breathe in oxygen and breathe out carbon dioxide, which plants use again. Microbes in the soil break down waste into nutrients. The only thing coming in is light energy, so the bottle is a closed system for matter but open for energy.

Observing and recording stability

Make a record table: date, water colour (clear or green or murky), plant condition (green, yellow, dead), animals alive, notes. Check every 2โ€“3 days for 4โ€“8 weeks. Do not open the bottle. Take photos from the same spot.

Signs of balance: clear water, green plants, active animals. Signs of trouble: murky or green water (too many nutrients or animals), yellow plants (too little light), fogged, hot glass (too much sun), dead animals. Ask: what changed, and how do we fix it in the next bottle?

What can go wrong (and why)

Key formulas and definitions

Worked examples

1. A bottle has 2 plants and 8 snails. The water is murky and snails die. Why?

Too many animals: they used up oxygen and made too much waste. Fix: fewer snails (2 or 3) and more plants.

2. A bottle is kept in a dark cupboard. After a week plants are yellow. Why?

Without light, plants cannot do photosynthesis, so they make little food and oxygen. Keep the bottle in bright, indirect light.

3. Why do we keep the lid closed once the bottle is sealed?

Opening would let gases and organisms in or out and break the closed cycle you are studying.

4. A student keeps the bottle on a sunny window and the glass is hot. What happens?

Heat stress: warm water holds less oxygen and animals suffer. Move to bright, indirect light.

5. Name the producer, consumer and decomposer in the bottle.

Producer: water plants. Consumer: snails. Decomposers: microbes in soil.

Common mistakes

Practice quiz

1. Which makes oxygen in the bottle?
2. What enters a sealed ecosphere from outside?
3. Too many animals will:
4. Decomposers in the soil:
5. Best place for the bottle:

Practice: answer these yourself

Type or choose your answer, then press Check. Use a hint if you are stuck; the full solution appears after you answer.

Frequently asked questions

What is a sealed ecosphere bottle?

A closed bottle with plants, animals and soil that recycle air and nutrients using light energy.

How long can an ecosphere bottle last?

If balanced, many weeks or even months. Many fail early if there are too many animals or too much heat.

Can I open it to check?

Better not to. Opening breaks the closed cycle. Observe through the glass and record.

Learn first

Learn next

Related lessons

All Biology lessons