Energy Flow in Ecosystems 3 4 Energy Flow

Energy Flow in Ecosystems 3. 4

Energy Flow �When an animal eats a plant, energy is transferred from plant to animal �The same thing happens when an animal eats another animal �The transfer of energy through an ecosystem can be traced �This helps scientists see how organisms are connected and how much energy is transferred

Food Chains �Show organisms in an ecosystem get their food �Each organism is a link in the chain and provides food for the next link �Always starts with a producer �Always ends with a consumer �Example:

Grasslands of Africa pg. 96 �Acacia trees producer �As producers, the trees make their own food using sunlight �Giraffes primary consumer �They eat the leaves and get some of the energy stored in them �Lions secondary consumer �Lions feed on giraffes and get the energy stored in their cells

Food Webs �Most organisms are a part of more than one food chain �This network of feeding relationships is called a food web �Eating many different foods can help a consumer make sure it can find enough food �Pg. 97

Trophic Levels �Feeding level in a food chain or web �Producers make up the first trophic level �Green plants in a grassland ecosystem �Algae in an ocean ecosystem �In few ecosystems, bacteria form the first level

Primary, Secondary, and Tertiary �The second trophic level is made up of herbivores (primary consumers) �The third trophic level is made up of carnivores (secondary consumers) �These feed on primary consumers �In some food chains, there is a fourth or fifth level of consumers (tertiary consumers) �These consumers eat other consumers

Energy Pyramids �Which are there more of: producers or consumers? _________ �Trophic levels form a pyramid because there are many more producers than primary consumers �Producers form the bottom of the pyramid �There are more primary consumers than secondary consumers

Think about it this way… �A field of grass can only support a certain number of rabbits �The number of rabbits can only support a smaller number of bobcats �The bobcats can only support an even smaller number of cougars

Energy Transfer �An pg. 99 energy pyramid shows the amount of energy available at each trophic level �Each time energy is transferred, about 90% is lost �Some is lost to heat and escapes into the atmosphere �Only 10% gets stored in the consumer �As you move up the pyramid, less food energy is available

The pyramid break down �The first trophic level is the largest and has the most energy �Each level above it has less energy and fewer species �The top level (tertiary) has the smallest amount of energy �This is why there are more small animals than large animals in an ecosystem �Food chains only have 4 -5 links

Vocabulary �Food Chain �Food Web �Trophic Level �Primary Consumer �Secondary Consumer �Tertiary Consumer