Download Food Webs

What are food webs?
0 In most food chains,
each type of organism is
eaten by more than one
type of consumer-this
can make organisms a
part of more than one
food chain
0 FOOD WEB- a network
of food chains that have
some links in common
0 Food webs are just several
food chains put together.
0 A food web tells you a lot
about the living things in
an ecosystem
0 COMPETITION is the
struggle between
organisms for the same
resource
0 Life in an ecosystem is a
constant struggle
How can food webs change?
0 When one population in a
food web changes, ALL the
other populations in the
food web can be affected
0 When top carnivores are
removed, prey populations
are no longer controlled
0 Prey populations increase
in number, they need more
producers to supply them
with food.
0 Page 149 Sea otters eat
several animals in the
kelp-forest but in the
1800s too many sea
otters were hunted for
their fur. The sea urchin
population was soon out
of control
How do new organisms
change food webs?
0 Humans can change
ecosystems by
introducing new species
0 EXOTIC SPECIES- are
non-native plant and
animal species that have
been introduced into an
environment
0 These plants and
animals can threaten
native species
0 In a food web, organisms
compete with each other
for food and other
resources. When an
exotic species is
introduced into an
ecosystems, it also
competes with native
species for resources
ALL FOOD CHAINS MUST
HAVE BALANCE!!!