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 source”
A Basic Food Chain
Plants absorb light from the
sun, which is turned into
energy to grow. We call
these producers.
The vegetarian animals eat
the plants, they are called
primary consumers.
Secondary consumers
prey on primary
consumers.
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 photosynthesis.
• Animals are consumers because they cannot
create their own food, they must eat plants or
other animals to get the energy that they
need.
Producers
Producers are organisms that use
energy from the Sun to make their own
food through a process called
photosynthesis. You can think of a
producer as an organism that produces
its own food. Most producers are
plants. However, algae and some
bacteria are producers, too. The
grasses, shrubs, and trees in a meadow
are examples of producers. These
types of producers are common in
grasslands and forest ecosystems.
Algae are common producers in
estuaries and marine ecosystems.
Primary Producers
• Primary producers are “organisms capable of
producing their own food”
• 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
Cattails
Bulrush
phytoplankton
Algae
Consumers
Some organisms must get
energy by eating other
organisms. These organisms
are called consumers.
Consumers can be organized
into three groups: herbivores,
carnivores, and omnivores.
Three types of consumers
• Herbivores: animals that eat only plants
• Carnivores: animals that eat only other
animals.
• Omnivores: animals that eat animals and
plants.
Carnivores
Carnivores are consumers that eat only other
animals. In marine ecosystems, sharks,
walruses, seals, and octopuses are common
carnivores. In land ecosystems, lions,
wolves, hawks, and eagles are common
carnivores. Some carnivores are called
scavengers. These carnivores eat animals
that are already dead. Most of the time,
scavengers eat leftovers from other
carnivores. One example of a scavenger is a
vulture.
Omnivores
Omnivores are consumers that eat both plants and animals.
Since they can eat a variety of organisms, omnivores can easily
adapt to changing environments. Pigs, bears, raccoons, and
humans are examples of omnivores.
Organisms such as fungi and bacteria get energy in a different
way than producers or consumers. These organisms, called
decomposers, get energy by breaking down nutrients in dead
organisms. As they break down the nutrients, decomposers
produce simple products such as water and carbon dioxide.
These products are returned to the ecosystem for other
organisms to use. Decomposers are very important because they
return nutrients and products to the ecosystem. One way to
think of decomposers is as recyclers. Termites and earthworms
are examples of decomposers.
Decomposers
• Decomposers- are organisms that break down
dead plant and animal matter into simpler
compounds
Other Ways to Classify Consumers
1. Primary Consumers: Herbivores.
2. Secondary Consumers: Carnivores that eat
herbivores.
3. Tertiary Consumers: Carnivores that eat
other carnivores.
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!
What is a food web?
A food web is “an interlocking pattern of food
chains”