What is the main source of energy in all ecosystems? The Sun!

Interactions & interdependence in an ecosystem are all about energy transfer! Meaning, when studying how/why organisms interact & the roles they play in their environment, we have to understand how energy is flowing through the environment!

Feeding Relationships

Autotrophs/Producers Organisms that can make their own food from the sun or chemicals Some bacteria can make their own food from chemicals, called chemosynthesis. Plants make their own food using energy from the sun via photosynthesis.

Heterotrophs/ Consumers Organisms that eat or absorb food to obtain energy

Different Types of Heterotrophs Herbivores: eat only plants (aphids) Carnivores: feed on other consumers (tigers) Omnivores: eat producers & consumers (bears)

Different Types of Heterotrophs Detritivores & Scavengers: feed on dead materials (vulture) Decomposers: break down organic matter and return it to the environment to be recycled (fungi)

Scavengers vs. Decomposers Scavengers feed off dead animal materials, consuming the organic matter. Decomposers break down organic matter & create inorganic matter that will be returned to the soil. – In other words, they break down decaying plants or animals into simpler chemicals that can be recycled through the environment.

Heterotroph & Omnivore! A.Heterotroph & Carnivore B.Autotroph & Herbivore C.Heterotroph & Decomposer D.Autotroph & Decomposer E.Heterotroph & Omnivore F.Autotroph & Producer

Heterotroph & Decomposer! A.Heterotroph & Carnivore B.Autotroph & Herbivore C.Heterotroph & Decomposer D.Autotroph & Decomposer E.Heterotroph & Omnivore F.Autotroph & Producer

Autotroph & Producer! A.Heterotroph & Carnivore B.Autotroph & Herbivore C.Heterotroph & Decomposer D.Autotroph & Decomposer E.Heterotroph & Omnivore F.Autotroph & Producer

Heterotroph & Carnivore! A.Heterotroph & Carnivore B.Autotroph & Herbivore C.Heterotroph & Decomposer D.Autotroph & Decomposer E.Heterotroph & Omnivore F.Autotroph & Producer

Food Webs & Food Chains Show how energy flows through an ecosystem Energy Flow: energy flows in 1 direction through an ecosystem Sun  Producers  Consumers  Decomposers At each level, some energy is used by the organism for life processes & is “lost” as heat.

Food Chains Single display of energy transfer in an ecosystem – arrows point in the direction of energy flow The snake gets energy from eating frogs, so the arrow points toward the snake.

Food Webs Link together several food chains within the same ecosystem

Trophic Levels Steps or levels in a food web, chain, or food pyramid Producers Primary consumers Secondary consumers Tertiary consumers

Trophic Levels Each consumer depends on the trophic level below it for energy. The 1 st trophic level always includes producers; the 2 nd includes primary consumers, etc.

Primary consumer Secondary consumer Tertiary consumer Trophic Levels

What trophic level do weasels belong to? A.Producer B.Primary Consumer C.Secondary Consumer D.Tertiary Consumer Secondary Consumer

What trophic level do raccoons belong to? A.Producer B.Primary Consumer C.Secondary Consumer D.Tertiary Consumer Primary AND Secondary Consumer!

To show relative amounts of matter & energy per trophic level, we can use a pyramid. – Energy Pyramid – Biomass Pyramid Ecological Pyramids

Energy Pyramids Producers at the bottom with the total amount of solar energy captured Notice how the amount of energy changes with every trophic level.

Energy from the sun is captured in plants. Food chains usually go up only 4-5 levels. WHY? Energy transfer is inefficient!

10% Rule Only 10% of the energy is passed on to the next trophic level. Why? The other 90% is used by the organism for life processes or lost as heat.

Inefficiency of Energy Transfer What do we mean by “lost” as heat? To where is this energy lost? 10-15% Growth 35-40% Cellular Respiration 50% Waste (feces) Only this energy moves on to the next level in the food chain! Energy lost to daily living.

If 5600 kCal were available at the producer level, how much would be available at each of the other trophic levels? 5600 kCal 560 kCal 56 kCal 5.6 kCal

Biomass Pyramids Show the amount of food or energy available at each trophic level as a weighted mass