Energy Flow Food webs Pyramids

Classifying Organisms  Producer: organisms that can use inorganic sources to make their own food (e.g. plants)  Consumer: organisms that eat other organisms to obtain energy  Predator: animals that catch and feed on other live animals  Prey: animals that are hunted and eaten by others  Top carnivore: organism at the top of the food chain that is not hunted or consumed by another organism

Types of Consumers  Herbivore: eat plants  Carnivore: eat animals  Omnivore: eat both plants and animals  Decomposer: breakdown organic matter and release nutrients back into the ecosystem Scavenger: carnivores that eat remains of animals, usually freshly killed (e.g. vultures) Detritivore: eat remains of plants and animals and animal waste (e.g. earthworms, maggots, bacteria)

Energy in Ecosystems  The source of all energy is the SUN. PLANTS use the suns energy to make food.  Most of the sun’s energy never reaches the Earth’s surface but is reflected or absorbed by gases in the upper atmosphere.  Of the energy that reaches the lower atmosphere, 30% is reflected by clouds or Earth’s surface and 70% is absorbed.  Greenhouse gases allow energy from sun to enter but prevent energy from leaving.

Energy in Ecosystems  Albedo Effect is the measurement of the percentage of light an object reflects  The HIGHER the albedo, the GREATER the object’s ability to reflect sunlight  Substances that have high albedo: snow, clouds  Substances that have low albedo: soil

Energy Movement  Food chains show simple feeding relationships  Food chains do not exist in nature  Food webs are a number of interconnecting food chains  Even food webs aren’t accurate

Which is more accurate and why?

Trophic Levels  Trophic levels: feeding levels that describe the position of an organism along a food chain 1 st trophic levels always contain producers 2 nd trophic levels contain herbivores 3 rd trophic levels contain consumers that eat herbivores  Classification of organisms at the trophic levels Primary consumer: eats producers Secondary consumer: eats primary consumers Tertiary consumer: eats secondary consumer  An organism can change its trophic level depending on the food chain

Trophic Levels

Different Forms of Energy  Sound, solar, kinetic, potential, thermal, electric, nuclear energy

Laws of Thermodynamics  Thermodynamics is the study of energy transformations  First Law: Energy can be transformed (changed) from one form to another but it cannot be created or destroyed

Examples of Energy Transfer  Light bulbs convert electrical energy into light and heat energy  People eat food (chemical energy) which provides fuel for their bodily functions (running) which corresponds to kinetic energy, thermal energy and sound energy  Cars convert chemical energy (gas) to kinetic energy, thermal and sound energy

Energy Loss  There is always a loss of energy with each level because: some energy is released to the environment as thermal energy (heat) not all parts of an organism is eaten  Only about 10% of energy taken in by an individual is passed onto the next level  Organisms at the highest trophic levels have less energy available to them than species at the bottom

Laws of Thermodynamics  Second Law: During any energy transfer, some energy is lost because it is converted to an unusable form such as heat

Ecological Pyramids  Displays relationships between trophic levels in an ecosystem  Three types of ecological pyramids: Energy Numbers Biomass

Energy Pyramid  Illustrates energy loss and transfer between trophic levels  Size of each layer represents amount of energy available at each level

 Pyramids of energy are difficult to measure because it is hard to measure the amount of energy in an organism without killing the organism.  Energy is measured using kilojoules (kJ)

Pyramid of Numbers  illustrates the number of organisms at each trophic level  As the trophic levels increase the number of organisms often decrease  Example: grass  mouse  fox

Pyramid of Numbers  Sometimes the number of organisms increase up the trophic level  Example: trees  insects  parasites

Pyramid of Numbers

Biomass Pyramid  Biomass is the dry mass of an organism after water is removed from its tissues  Pyramid illustrates the total mass of individuals at each trophic level

Pyramid of Biomass  Biomass pyramids usually take on the same shape as the corresponding numbers pyramid

Some Exceptions  Comparing Pyramids: number vs biomass

Characteristi cs being compared Hunter-GathererAgricultural Revolution Industrial Revolution Food supply Collected edible plants and hunted animals. Social Structure Small groups, little population growth because of limited resources. Energy consumption and impact on surrounding ecosystems Low energy demands on the ecosystem because of nomadic lifestyle which allowed ecosystems to recover after groups moved to new area.

Characteristi cs being compared Hunter-GathererAgricultural Revolution Industrial Revolution Food supply Collected edible plants and hunted animals. Plants and animals were domesticated. Social Structure Small groups, little population growth because of limited resources. Shift from nomadic lifestyle to farming. Greater population growth. Energy consumption and impact on surrounding ecosystems Low energy demands on the ecosystem because of nomadic lifestyle which allowed ecosystems to recover after groups moved to new area. Trees were cut to make houses and create farmland. Greater demand for energy and water to run the farms.

Characteristi cs being compared Hunter-GathererAgricultural Revolution Industrial Revolution Food supply Collected edible plants and hunted animals. Plants and animals were domesticated. Farming resulted in even greater food production. Social Structure Small groups, little population growth because of limited resources. Shift from nomadic lifestyle to farming. Greater population growth. Population continues to grow and cities thrive. Energy consumption and impact on surrounding ecosystems Low energy demands on the ecosystem because of nomadic lifestyle which allowed ecosystems to recover after groups moved to new area. Trees were cut to make houses and create farmland. Greater demand for energy and water to run the farms. Even greater demand for energy to run machines. More damaging for the environment.

Gizmo   Grade 9-12 biology  Ecology and interdependence  Food chain