Energy Flow in Ecosystems Section 1.2 Pgs. 31-32

Relationships Among Organisms All organisms need Energy to survive. Food contains nutrients, which are substances the organisms use to build and repair cells in their body. Food also contains energy which all organisms need to grow and maintain their bodies, and to reproduce.

Energy in Ecosystems The Sun provides light and heat energy and is the ultimate source of energy for life. Plants can make their own food through photosynthesis

Producers take energy from the sun and make it into chemical energy for living things (SUGAR). not all the energy is stored in the plant most is used by the plant to survive, grow and live!

How Energy flows Consumers eat other organisms, both plants and animals in order obtain energy. Cellular Respiration: Sugar in food (glucose) gets converted into cellular Energy (ATP)

Food Chains To understand the complex way that energy flows from producers to consumers in an ecosystem, we use visual diagrams called food chains A Food Chain shows how the energy that is stored in food is transferred from one living thing to another.

The food chain to the left is a very basic (3 trophic levels)representation of a food chain found in nature. The plant (producer) is eaten by the primary consumer (herbivore) which is then eaten by the secondary consumer (omnivore or carnivore).

Try this See p23 in text try activity A4

Not always so simple Food chains provide a very basic view of one set of predator-prey relationships. In an ecosystem with a lot of biodiversity, however, a food chain gives a very limited view. For this reason, we use food webs to describe the more complex interactions in an ecosystem.

Parts of a Food Chain Producers – use the sun’s light to create their own food. - plants Consumers – animals that can’t make their own food, and obtain food by eating other plants or animals. Herbivores – animals that eat ONLY PLANTS - called primary consumers

Carnivores – Animals that eat OTHER ANIMALS Secondary Consumers if they eat herbivores Tertiary (3rd Order) Consumer if they eat other carnivores.

Parts of a Food Chain Omnivores- Animals and People who eat both PLANTS AND ANIMALS Decomposers or Detrivores - such as bacteria, fungi, earthworms, and other insects. - Break down organic matter in dead plants and animals and release nutrients back to the environment. (will be used in the nutrient cycles)

Scavenger An animal, such as a bird or insect, that feeds on dead or decaying matter.

Trophic Levels Eagle – Top Carnivore - 3rd Order consumer Snakes – Carnivore - 2nd order consumer Rats – Herbivores /Omnivore First Order Consumer Plants - Producers

FOOD WEB In this basic food web, it is easy to see how complex the interactions can become in a system with high biodiversity

Tracking the energy Using food webs and chains,we can see what eats what, but to see how much energy is actually passing along, we need to use Energy pyramids. Energy pyramids show the amount of available energy that each level of a food chain gets. Each organism passes about 10% of the energy it takes in, so the longer the chain, the less energy is available at the top.

Where does the Energy go? Where does all the energy go? Approximately 60% of the energy cannot actually be consumed by the predator but leaves the prey in its wastes mostly as heat. The remaining 30% is used to run the cellular processes of the body (cellular respiration, digestion, reproduction, growth and healing).

Example of an Energy pyramid In this pyramid, you can see that each level going up the pyramid has 10% of the energy of the lower level. Hawk - 100kJ Robin - 1000kJ Aphids - 10000kJ Oak tree - 100000kJ

Biomass Pyramid Many trees & shrubs provide food and energy to giraffes. As we go up, there are fewer giraffes than plants and even fewer lions than giraffes ... In other words, a large mass of living things at the base is required to support a few at the top .

What we're working on today Food Web Assignment