Food Chain, The (GMHDRNC)
The house of cards analogy will illustrate how animals are interdependent in the food chain. They will discuss the role of producers and consumers and the effects of different rates of reproduction. A live bird of prey or alligator may be examples of top predators.
K - 12
Indoor or outdoor classroom
Governor Mike Huckabee Delta Rivers Nature Center, Pine Bluff
Education Program Coordinator, 870-534-0011
45 minutes - 1 hour
Suggested Number of Participants:
10 - 30
- Appreciate the interconnectedness of animal species.
- Discuss the transfer of energy between organisms.
Transfer of energy
*See glossary for definations
A food chain is a diagram that shows how food (or energy) moves through an ecosystem. Plants provide the base for all food chains because they are producers. This means they can produce their own food via photosynthesis by converting water and carbon dioxide into sugar molecules and oxygen. All nonphotosynthesizing organisms are considered consumers. Consumers must get their energy from other organisms.
- Discuss the transfer of energy between organisms. Whether the consumer is an herbivore (eat only plants) or a carnivore (eat only meat), energy must be transferred from one organism to another. Transferring energy involves a substantial decrease in energy with each consumer involved. With each transfer, the energy obtained will be only 10 percent of the energy obtained by the previous consumer. For example, as a cow eats grass, the energy that the grass obtained from photosynthesis will be greatly diminished in transferring to the cow because most of the energy built molecules in the plant, and some is lost as heat. If the grass has 100 parts of energy available, only 10 will transfer to the cow. When a human or another carnivore eats the cow, the small amount of energy the cow received from the grass will be even smaller when transferred to the human. The human will have 10 percent of the 10 parts available, giving it a gain of only one part.
- The food chain shows how all living things are connected. Discuss the concept of ecology using the house of cards analogy.
- Much like removing a single card from the delicate tower of cards, if one part of the food chain is removed, the entire chain will be damaged.
- In a pond example, if you remove plants, the smaller fish and other organisms that rely on them will die because of a lack of resources. When the smaller fish die, the larger predatory fish will also be affected because they depend on the smaller fish for food. A similar problem occurs if the top of the food chain is removed. If large predatory fish are taken out, the number of small herbivorous fish will explode because of the lack of natural predators. If there are too many small fish, the plant population will be exploited, and eventually many of the smaller fish will die because the food source will run out. Therefore, it is important to maintain all pieces of a food chain.
- Present the educational animal to the class. This can also be done throughout the discussion as a visual aid.
- Answer any questions.
Consumer – in ecology, an organism, usually an animal, that feeds on other organisms and their remains; classified as primary consumers (herbivores), secondary consumers (carnivores) and microconsumers (decomposers)
Ecology – branch of biology dealing with the interactions between organisms and their environment
Producer – an organism that creates its own food from inorganic substances through photosynthesis (by green plants) or chemosynthesis (by anaerobic bacteria) and serves as a source of food in the food chain
Transfer of energy – the passing of energy from one level to another through predation and consumption