Food Chains
and Food Webs
What is a food chain?
• A food chain is “a sequence of organisms,
each of which uses the next, lower member of
the sequence as a food source1”
Important facts about food chains
• In a food chain each organism obtains energy
from the one at the level below.
• Plants are called producers because they
create their own food through
photosynthesis3
• Animals are consumers because they cannot
create their own food, they must eat plants or
other animals to get the energy that they
need.
The Producers
Producers are the beginning of a
simple food chain. Producers are
plants and vegetables.
The Producers
All energy comes from
the Sun and plants are the
ones who make food with
that energy. They use the
process of photosynthesis.
Plants also make loads of
other nutrients for other
organisms to eat.
Primary Producers
• Primary producers are “organisms capable of
producing their own food4”
• We can also say that they are photosynthetic, use
light energy.
• Examples of primary producers include algae,
phytoplankton, and large plants.
• Primary producers are eaten by primary consumers
(herbivores)
Primary Producers of Common
Marshes
Marsh Mallow
Cattails
http://www.nicerweb.com/doc/class/pix/PRAIRIE/2005_07_18/Typha_angustifolia.jpg
http://www.ncdot.org/doh/Operations/dp_chief_eng/roadside/wildflowerbook/graphics/images/page14a.jpg
Marsh Fern
Blue Flag Iris
http://www.ontariowildflower.com/images/blueflag2.jpg
http://wisplants.uwsp.edu/scripts/detail.asp?SpCode=THEPALvPUB
The Consumers
Consumers are the next link in
a food chain. There are three
levels of consumers.
•Primary consumers (1st Order)
–Worms, insects, squirrels, mice: all eat plants
(HERBIVORES) ex: squirrel eats acorns
•Secondary consumers (2nd Order)
–Eat the primary consumers (CARNIVORES) example:
cat eats squirrel
•Tertiary consumers (3rd order)
–Eat the primary and secondary consumers (CARNIVORES) ex:
wolf eats cat and squirrel
Other Ways to Classify Consumers
1. Primary Consumers: Herbivores.
2. Secondary Consumers: Carnivores that eat
herbivores.
3. Tertiary Consumers: Carnivores that eat
other carnivores.
Four types of consumer
• Herbivores: animals that eat only plants3
• Carnivores: animals that eat only other
animals3.
• Omnivores: animals that eat animals and
plants3.
• Detritivores: Animals that eat dead materials
and organic wastes
Primary Consumers in Marshes
Muskrat (eats mostly Cattails)
http://wdfw.wa.gov/wlm/living/graphics/muskrat1.jpg
http://www.advancedwildlifecontrolllc.com/images/muskrat.jpg
Primary Consumers in Marshes
• Wood Duck eats seeds like those of the
Swamp Marsh Mallow and Blue Flag Iris
http://dsf.chesco.org/ccparks/lib/ccparks/wood_duck_pair.jpg
Primary Consumers in Marshes
• Glassy-winged Toothpick Grasshopper – eats
leaves of plants like cattail and pickerelweed
http://bugguide.net/node/view/41662
Secondary Consumers
• Black Rat Snake eats eggs of animals like wood
duck
http://www.bio.davidson.edu/projects/tate/Terms.htm
Secondary Consumers
• Swamp Sparrow eats seeds but also insects
like the toothpick grasshopper
http://www.jeaniron.ca/2007/SwampSparrow6645.jpg
Tertiary Consumers
• Eat other animals in marsh including snake
and sparrow
Osprey
www.montereybay.com
www.audubon.org
Omnivore
• Racoon eats seeds, fruits, insects, worms, fish,
and frogs… and pretty much anything else
they can get their paws on!
http://abouttitusville.com/BobPaty/Animals/images/Racoon.jpg
Detritivore
• Worms are common detritivores in many
ecosystems including marshes
The Decomposers
The last links in the chain are the decomposers. (They break things
down) Like bacteria, mold, fungi, mushrooms
•If you die, they eat you.
•If you poop, they eat that.
•If you lose a leaf, they eat it.
Whenever something that was alive dies, the decomposers get it.
Decomposers break down nutrients in the dead
"stuff" and return it to the soil.
The producers can then use the nutrients
and elements once it's in the soil.
The decomposers complete the system,
returning essential molecules to the
producers.
What is a food web?
A food web is “an interlocking pattern of food
chains2”