Seminar Unit 4

Food Chain – The sequence in which living things depend on other living things for food.

What is a Food Chain? All living things need food to give them the energy to grow and move. – A food chain shows how each living thing gets its food. – A food chain shows who is eating who. – The arrow means "is eaten by". Grass  Grasshopper  Toad  Snake >Hawk

Food Chain A food chain always starts with a green plant (All plants are PRODUCERS.) Plants are eaten by an animal. ( All the animals in a food chain are CONSUMERS) A food chain ends with a predator. (The predator is at the top of the food chain)

A Food Web consists of many food chains.

What is the difference between a Food Web and a Food Chain? A food chain only follows just one path as animals find food. A hawk eats a snake, which has eaten a frog, which has eaten a grasshopper, which has eaten grass.

What is the difference between a Food Web and a Food Chain? A food web shows the many different paths plants and animals are connected. A hawk might also eat a mouse, a squirrel, a frog or some other animal. The snake may eat a beetle, a caterpillar, or some other animal. And so on for all the other animals in the food chain. A food web is several food chains connected together.

Food Web

Do you live on a food chain or a food web? Why do you think it is better to live as part of a food web than on a food chain?

In the Lake Michigan food web, what might happen to the population of blue-green algae if the amphipods started dying?

What would happen to the population of Lake whitefish if the amphipods started dying?

What might happen to the mollusks if the amphipods started dying - even though the mollusks aren’t directly connected to the amphipods?

The Law of Unintended Consequences It is virtually impossible to change one aspect of a complex system without affecting other parts of the system, – Often in as-yet unpredictable ways

In food chains and food webs, only about 10% of the energy expressed as calories from eating a creature get transferred up into the next level of the food chain. What happens to the other 90% of the calories?

Energy Flows Through Ecosystems Trophic levels are all organisms that get their energy fro the same source – 1 st trophic level: plants use sun’s energy to provide energy for herbivores in the 2 nd trophic level – and so on….. – In each energy transfer from one trophic level to another, most of the available energy cannot be recovered in a useful form It eventually radiates into space as waste heat As energy flows through an ecosystem, it must be replaced continuously

References junior.kent.sch.uk/Homework/fooodchains.ht m