THE BALANCE OF LIFE

Life on Earth is a vast jigsaw of plant and animal activity. The world can be split into vegetation regions according to the kind of plants that thrive there. Scientists often break down the vegetation regions into smaller units, such as tropical rainforests or freshwater lakes. They might go further to identify individual trees or a pond. Each unit, where the creatures living there interact with each other, is called an ecosystem.

An ecosystem is a community of living things, or organisms, that all depend on each other. An aquarium like the one in the project is a miniature freshwater ecosystem. All plants need particular conditions of soil and climate to survive. Animals also survive by adapting to, and interacting with, their surroundings and the local climate.

If a particular species from an ecosystem is removed, the existence of other living things is threatened. If the plants on which a certain caterpillar feeds are destroyed, the caterpillars die. Eventually, the birds that feed on the caterpillars, and the foxes that feed on the birds would starve.

Make your own aquarium ecosystem

YOU WILL NEED

Gravel, net, plastic bowl, pitcher, water, aquarium tank, rocks and pieces of wood, water plants, pond water, water animals.

STEP 1
Put the gravel in a net. Rinse it in a plastic bowl of water, or run it under the cold water tap in the sink. This will discourage the formation of green algae.

STEP 2
Spread the gravel unevenly over base of the tank to a depth of about 1¼in. Add rocks and pieces of wood. These give surfaces for snails to feed on.

STEP 3
Fill the tank to about the halfway mark with tap water. Pour the water gently from a pitcher to avoid disturbing the landscape and churning up the gravel.

STEP 4
Add some water plants from an aquarium store. Keep some of them in their pots, but remove the others gently. Then root them in the gravel.

STEP 5
Now add a pitcherful of pond water. This will contain organisms, such as daphnia (water fleas), which add to the life of your aquarium. You can buy pond water in a garden store.

STEP 6
Add a few of the water animals you have collected from local ponds, such as tadpoles in frog spawn, or water snails. Take care not to overcrowd the aquarium.

STEP 7
Place the tank in bright light, but not in direct sunlight. You can watch the plants in the tank grow. Keep the water clean by removing dead matter off the gravel every few weeks.

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