But what sustains life? Energy sustains life, and it is the flow of this energy through the ecosystem that we are studying here. Each organism in the ecosystem has a certain role related to how it acquires and releases energy. Some organisms produce energy - the producers, and some organisms consume energy - the consumers. Only plants are producers.

There are several main sources of energy: the sun, plants, and other animals for example. Organisms that get their energy from a common source are, together, called a trophic level. For example, plants comprise a trophic level.

Plants get their energy from the sun through a process called photosynthesis. The herbivores, which eat the plants, get their energy from the energy stored in the plants. Similarly, carnivores, which eat animals, get their energy from the energy stored in the animals' bodies. This transfer of energy is known as an energy pyramid. The plants form the base of the pyramid. Above the plants are the herbivores, and on the top of the pyramid are the carnivores. Each time you move up a level in the energy pyramid, a large amount of energy is lost to the environment. This happens because, when energy changes forms, some of the energy has to be used to make the change, thus it is lost to the environment. For example, this could occur in the form of heat. So, the most energy efficient organisms are those that get their energy directly from the sun. The least energy efficient are the carnivores who get their energy filtered through the plants and the herbivores.

Of course, there are other factors that are also involved in the ecosystem. There are environmental factors such as weather, and there are diseases, and finally there are humans. Humans have the capacity to make a very large impact on an ecosystem very quickly.

The food chain is not actually a straight chain. It is often described as a food web. Energy does flow in one direction, from plants up to carnivores, on a large scale. On a smaller scale, however, there is plenty of energy transferred within a trophic level. If you drew a diagram of a food chain, it would end up looking very much like a spider's web, with many interconnected lines. Below is an example of a food web. The arrows point in the direction that the energy flows.

In the Survival Game, the food web is created by dividing the players into the various animal categories such as herbivores, omnivores, and carnivores. Each category is given a certain number of lives (say 9 lives for a herbivore, 6 lives for an omnivore, and 3 lives for a carnivore). Now everybody goes to a big field and the wild is set up. The carnivores chase and eat a life from either an omnivore or a herbivore, the omnivores can eat a herbivore but must also find food (a part of the game not yet introduced), and a herbivore is constantly running for its life and having to find food for survival. Each player runs around until his lives are exhausted and he has to retire to a restful, peaceful haven. Lives are simply represented by tags that the players carry around with them; to lose a life the animal must be touched by a higher ranking animal on the web (the predator takes and keeps the acquired tags).

• At least 30 people.
• A big field to play in.
• Something to denote each player's number of lives. The herbivores each get 9 lives. Omnivores get 6 lives, and carnivores get 3 lives. The "lives" can be made from coloured construction paper to match the animal's colour.
• To denote the player's role, you need enough material to make green, blue, red, and white headbands. There should be at least twice as many herbivores as omnivores. There should be 2/3 as many carnivores as omnivores, and there should be only one of each element.
• One survival card for each player - they can be made out of bristol board.
• Ink pads and stamps for vegetation, water, and shelter.
• Socks.
• Rings of some sort, for each player, with coloured material tied on to represent which colours they're allowed to chase.

Basically, the premise of the game is that the carnivores chase and eat a life from either an omnivore or a herbivore, the omnivores can eat a herbivore but must also find food. This food, as well as shelter, and water are hidden around the field. Finally, the herbivores are constantly running from their predators, the omnivores and carnivores, and they are searching for food for survival.

A player, representing an animal, moves through the game until his lives are exhausted. Lives are simply represented by tags that the animals carry with them. To lose a life, the animal must be touched by a player who represents a higher ranking animal on the web (the predator takes and keeps the acquired tags).

This was a simple introduction; the details are as follows:

There are 3 types of hidden stations: vegetation (food), shelter, and water. All the animals need to find the shelter and water stations to survive but the herbivores and omnivores need to find vegetation as well. These stations will consist of an ink pad and a stamp and will be hidden on the playing field. The animals must stamp their survival card at these stations.

To make the ecosystem more complete, disease, natural disaster, and humans are introduced. Disease is able to victimize any of the animals by throwing a sock at them and hitting them - this takes ONE life. A natural disaster can also victimize the animals by hitting them with a thrown sock - this takes TWO lives. The human has only to point at any player in the game (including disease and natural disaster) to do with him what she will. For example, the human could terminate the player's existence, or domesticate her in a zoo which would leave her completely unable to prey on another animal, or the human could replenish an animal's lives; the possibilities are endless.

To distinguish between each member of the food chain, the players will be given a specific coloured headband. The herbivores will wear green headbands, the omnivores white, the carnivores red, the elements blue, and the human should have a costume of some sort.

When a player has been caught by its predator, he must surrender the required number of lives. The predator must then wait 30 seconds before he may catch the same or another victim.

To begin the game every player is given a headband, markers for the appropriate number of lives, and a survival card (for the elements, instead of the survival cards, they're given a card stating how to capture other players). Then the herbivores are let to roam first, then the omnivores, followed by the carnivores, and finally the elements and the human.

Even the smallest change a human effects on an ecosystem can have a very large ripple effect. It's like dropping a pebble in still pond. When you drop the pebble into the water, it only touches a small area of the water, but the ripples that it creates disturb a much larger area of the water's surface. Similarly, when a change occurs in the environment, it may kill a certain species of plants. A certain species of herbivore may depend on that particular species of plant for survival, and if it disappears, so might that animal. And thus the ecosystem is interconnected.

In studying ecology, and how ecosystems work, humans have a reasonable understanding of how our actions have an effect on our world. It is now up to us to decide how to limit our impact on the environment so that we play a positive role in the ecosystem, not a negative one. Just like in the game, we have the power to support the ecosystem and its inhabitants, or to destroy them. It is our choice.