Food Webs: Land and Water

• Every organism on the planet, including humans, are connected through a food web.

Producers, Consumers, and Decomposers

• Producers• Make their own food using photosynthesis• Plants, green algae, kelp, phytoplankton

Consumers• Eat other organisms for food• Cow, human, eagle

Decomposer• Break down the remains of other organisms• Fungi and some bacteria• Vital to ecosystems because they return

important nutrients to the environment

Consumers are classified by their food source

• Primary Consumers– Eat only producers• A cow eating grass is a primary consumer

• Secondary Consumers– Eat primary consumers• Human eating a cow

Grass-producer

Toad-Secondary consumer

Grasshopper-primary consumer

Food Chain

• Flow of energy from one organism to next in an ecosystem

• Shows flow of energy from producer, to different consumers, and finally decomposers

• Shows only one path

Food Chain

Food Web

• Many food chains make up a food web• Food Web– Interconnected network of food chains within an

ecosystem

Aquatic Food Web

• Food web showing relationships between aquatic organisms

Terrestrial food web

• Terrestrial food web– Food web showing relationships between land

organisms

Terrestrial and Aquatic Food Webs

• They can also be connected– Bear eating fish out of a river– Birds diving for fish in lakes and oceans– Fish eating insects that land on the water

Food Chains and Food Webs

• Trophic Level– Each feeding level in an ecosystem is located

within a tropic level– Organisms at each tropic level take in energy from

the organisms they eat

Energy Flow Between Organisms-Pyramid

• Within an ecosystem, the energy flow between trophic levels does not remain constant

• At each level some animals use the energy taken in to perform life processes– Some energy is given off as heat– Some energy is stored in bones and teeth that

may not be eaten by another animal

Energy Flow between trophic levels

• Only 10% of the energy is passed onto the next higher trophic levelEnergy in an ecosystem can be measured in total

number of animals or combined mass of all animals

• Increase a level animals increase in size• Increase a level, animals decrease in number

Review

1. Which of these animals is a primary consumer? (eats a producer)

A CB

2. If the producers in an ecosystem produce 250,000 kilocalories of

energy, how much energy is available in the third trophic level?

• A. 5,000 kilocalories• B. 2,500 kilocalories• C. 250 kilocalories• D. 25 kilocalories

2. In a marine food web, which of the following would get its energy directly

from the sun?• A krill• B fish• C algae• D killer whale

3. Which of these animals is a secondary consumer?

A CB

4. Which of the following situations show a terrestrial and aquatic food

web connection• A. A seagull eating an insect on the beach• B. shark eating a tuna• C. seagull eating a fish• D. bear eating a deer

5. Which of the following situations show a terrestrial and aquatic food

web connection• A. A furry bear eating a tasty squirrel • B. An awesome human eating a slow deer • C. A swift pelican eating a large tuna• D. A frisky shark snacking on a cute dolphin

Create a terrestrial and aquatic food web poster.

• Your food web must have 6 animals• There must be two connections between

terrestrial and aquatic food webs.• Identify 1 primary consumer, 1 secondary

consumer, and 1 producer.