It is often quite tricky to ‘see’ all the relationships between the different plants and animals in an ecosystem and so scientists use the idea of a food web to show how different life on the reef is connected.

As you start to connect the different life on the reef with wool or string, you will start to see the web develop. A healthy reef requires a balance between the different living things. If any of the individual animals or plants is affected by human activity or natural events, then the whole reef is affected.

Activity steps

1. Cut out a ring of cardboard at least 20 cm in diameter, and the width of the ring at least 5 cm.
2. Punch 12 holes around the ring at evenly spaced intervals like a clock face.
3. Write the names of the following coral life next to the holes: coral, sea grass, phytoplankton, algae, crown-of-thorns starfish, green turtle, parrotfish, triton’s trumpet, tiger shark, manta ray, sea urchin, copepod.
4. Take a length of wool or string.
5. Tie the wool to a producer.
6. Link this producer to the next living thing along the food chain by passing the wool or string through each hole, e.g. link the algae to the sea urchin, and then to triton’s trumpet. Information about feeding habits of coral life is included in the Coral reef gallery.
7. When you have reached the top predator in that food chain, tie the wool around this hole to end the chain.
8. Repeat the process for all the food chains that you can identify on the reef. Once you have finished you will have completed a food web.

• Cardboard
• Glue
• Scissors
• Colored wool or string

Feeding relationships

When making the coral food web, it will be useful to understand some of the key words used to explain feeding relationships and the transfer of energy on the reef:

• Consumer: a living thing that relies on feeding on other living things for its energy, eg a shark is a consumer because it eats fish or a sea urchin is a consumer because it eats algae.
• Photosynthesis: the process by which producers create sugar (and therefore energy) from carbon dioxide and water using sunlight.
• Predator: an animal that eats other animals, eg a manta ray is a copepod predator.
• Prey: an animal that is eaten by another animal, eg a crown-of-thorns starfish is the prey of the triton’s trumpet.
• Producer: a living thing that produces energy via photosynthesis, eg algae is a producer because it creates energy from sunlight, carbon dioxide and water rather than eating something else.