Download 3202 Unit 3-1 Food Chains

Unit 3
Ecosystems
Ecosystem
Ecosystem - the network of relationships among
plants, animals and the non-living parts in an
environment.
Other examples:
Grasses
Trees shrubs
Water lilies
Flowers
Vegetables
Fruits
Producer - a plant which can synthesize carbohydrates
using carbon dioxide and the sun’s energy.
Actually “produce” their own food and food for the rest of
the ecosystem.
Consumers = All those organisms that have
to eat (consume) plants or animals to obtain
their food.
Types of consumers
Primary Consumers: Animals that eat
producers. Also called 1st. order consumers.
(Ex. Rabbit, squirrels, grouse, insects)
Secondary Consumers: Animals that eat
primary consumers. Also called 2nd. order
consumers. (fox, owl, mink )
Tertiary Consumers: Animals that eat
secondary consumers. Also called 3rd. order
consumers. (Wolf, coyote, hawk)
Examples:
Worms
Bacteria
Fungi
Protozoa
• Decomposers = Simple organisms that obtain
their food from dead/decaying organisms and
wastes.
Consumers, producers & decomposers….
Similarities
All three are terms
referring to the way
organisms obtain food &
energy
Differences
The way they obtain food
Producers make it,
Consumers eat it,
Decomposer feed on
wastes & dead material.
Food chain - linear
sequence
representing the
nutrition of
various species
from the simplest
plant to the top
carnivore.
Food web - a
series of
interconnecting
food chains in an
ecosystem.
Food Chain
vs
Food Web
Similarity
Both food chains and
food webs show the
flow of nutrients and
energy in an
ecosystem.
Difference
Food web is more
complex
Food web is composed
of several food chains
Food web is a more
realistic picture of an
ecosystem.
Identify examples of producers & consumers
and decomposers.
Producers
Shrubs, grass, trees
Primary Consumers
Grasshopper, rabbit, deer,
squirrel
Secondary Consumers
Mountain lion, snake, shrew,
insect-eating bird, hawk
Tertiary Consumers
Hawk, snake, mountain lion
Decomposers
Bacteria, fungi
Give an example
of a food chain
from fig. 6.4. P.
95
Tree
insect
→
Producer
→
Primary
consumer
insect eating
hawk
bird
→
2nd order
consumer
3rd order
consumer
Note: The arrows indicate the flow of energy & nutrients from
one level to the next
Sample Food Chain
What happens to energy at each level?
85-90% is LOST
or USED up:
in
maintaining
the organism
(Ex.
metabolism,
reproduction
etc.)
And as heat!!!
10-15% is
stored and:
Is available
or
transferred
to other
animals
when it is
eaten.
IF NOT EATEN:
This energy
is transferred
to the
decomposers
.
What happens to the energy at the
decomposer level?
Same thing….ALMOST !?
Most is lost or used up through heat
and maintaining the organism.
If eaten (Ex. A mushroom) energy gets
passed on.
HOWEVER, once a decomposer dies….
The energy is LOST FOREVER!!!
Summary – Energy & Food Webs
The ultimate source of energy (for most ecosystems) is the
sun.
The ultimate fate of energy in ecosystems is for it to be lost
as heat, metabolism, reproduction, etc..
Energy and nutrients are passed from organism to
organism through the food chain as one organism eats
another.
Decomposers remove the last energy from the remains of
organisms.
Summary – Energy & Food Webs