Primary Producers (Autotrophs)

•Capture energy from the sun or from chemicals
and store it in the bonds of sugars, making it
available to the rest of the community

•Energy from the sun is captured by plants,
algae, or bacteria through photosynthesis.

•Energy from chemicals is captured by some
bacteria through chemosynthesis.

Lesson 5.3 Ecological Communities

Did You Know?Deep-sea vents, far from sunlight,
support entire communities of fish, clams, and
other sea animals, which depend on energy
converted through chemosynthesis.

Consumers (Heterotrophs)

•Rely on other organisms for energy and nutrients

•Herbivores: plant-eaters

•Carnivores: meat-eaters

•Omnivores: combination-eaters

•Detritivores and decomposers: recycle
nutrients within the ecosystem by breaking down
nonliving organic matter

•Use oxygen to break bonds in sugar and release its
energy through cellular respiration (primary
producers do this, too)

Lesson 5.3 Ecological Communities

Did You Know?Scavengers, such as
vultures and condors, are just large
detritivores.

Energy in Communities

•An organism’s rank in a
feeding hierarchy is its
trophic level.
•Primary producers
always occupy the first
trophic level of any
community.
•In general, only about
10% of the energy
available at any trophic
level is passed to the
next; most of the rest is
lost to the environment
as heat.

Lesson 5.3 Ecological Communities

Pyramid of Energy

Numbers and Biomass in

Communities

•A trophic level’s
biomass is the mass of
living tissue it
contains.

•In general, there are
more organisms and
greater biomass at
lower trophic levels
than at higher ones.

Lesson 5.3 Ecological Communities

Food
Chains

and Webs

•Food chain: Linear
series of feeding
relationships

•Food web: Shows
the overlapping and
interconnected food
chains present in a
community

Lesson 5.3 Ecological Communities

•Species that have strong
and/or wide-reaching
effects on a community

•Removal of a keystone
species can significantly
alter the structure of a
community.

Keystone Species

Lesson 5.3 Ecological Communities