1. Food and Energy in
the Environment

2. Energy Roles
 Organisms may be producers,
consumers, or decomposers
 These terms indicate how an organism
obtains energy and how it interacts
with the other living things in its
community.

3. Producers
 Means that they make their
own food
 Able to use a source of
energy (sunlight) to turn
simple raw materials (such as
water and carbon dioxide)
into food (like the sugar
glucose).
 Producers are the source of
all the food in an ecosystem

4. Consumers
 Organisms that cannot
make their own food
depend on producers for
food and energy.
 An organism that feeds
directly or indirectly on
producers is called a
consumer.

5.  Herbivores: eat only
plants, such as rabbits
 Carnivores: eat only meat,
such as wolves
 Omnivores: eat both plants
and animals, such as humans
 Scavengers: an animal that
feeds on the bodies of dead
animals, such as jackals,
hyenas, and vultures

6. Decomposers
 After living things die,
organisms called decomposers
use the dead matter as food.
 Decomposers break down dead
organisms into simpler
substances.
 Molds, mushrooms, and many
kinds of bacteria are examples
of decomposers

8.  Essential to the ecosystem because they rid
the environment of the bodies of dead
plants and animals
 They also return nutrients (compounds
containing chemicals such as nitrogen,
carbon, phosphorus, sulfur, and magnesium)
to the environment, which are used by plants
to make food

9. Food Chains & Food Webs
 In general, food and energy in an
ecosystem flow from the producers to the
consumers in an ecosystem are
represented by food chains and food webs.
 Food chains represent a series of events in
which food and energy are transferred
from one organism in an ecosystem to
another

11.  Example: diatoms  krill  squid 
penguin  killer whale
 A food chain gives you a glimpse of the
food and energy relationships in an
ecosystem, but it does not give you the
whole picture

12. – There are many organisms
in an ecosystem and few
of them eat only one kind
of food
– There must be more than
one food chain in an
ecosystem
 A food web consists of many
overlapping food chains

14. Feeding Levels
A feeding level is the location of an
organism along a food chain
Producers form the first feeding level
Herbivores form the second feeding
level
Carnivores form the third feeding level

15.  At each feeding level, organisms use the
energy they obtain to digest their food,
reproduce, move, grow, and carry out
other life activities
 This means there is less energy available
to each level as you progress up the
feeding levels
 These levels form an energy pyramid