Download Ecosystems

Feeding relationships
• Basic terminology:
• Food chain: a simplified way of showing a
feeding relationship of an ecosystem. 1
consumer feeds on 1 consumer and so on.
• Food web: a more accurate way of showing
the feeding relationship may show 2 or more
consumers feeding on several organisms at a
time.
Producers are
organisms which make
their own food from
inorganic (non-Living)
sources, generally they
are plants and form
the basis of all food
chains.
Consumers are the
animals which consume
plants(producers) and
other organisms.
Producers
Plants
Primary
consumers
Herbivores
Decomposers
Secondary
consumers
Carnivores
Tertiary
consumers
Carnivores
Decomposers are organisms
which gain nutrients and
energy from dead matter.
All things die and so all food
chains lead to
decomposers. They make
the nutrients and energy
contained by the bodies of
the dead organisms
available to other organisms
Producers
First trophic level
•Each
organism
represents a
trophic or
feeding level
of a food
chain.
Plants
Primary
consumers
Second trophic level
Herbivores
Decomposers
Secondary
consumers
Third trophic level
Fourth trophic level
Carnivores
Tertiary
consumers
Carnivores
Available energy decreases down the
food chain:
Producers
• Only 10% of the energy At
each trohpic level is available
to the members of the next
level
100%
Primary
consumers
10%
Secondary
consumers
1%
Tertiary
consumers
0.1%
Example of a food web
Shows the
feeding
relationship
between
several animals
at once. Note
the many
branches.
At which trophic level(s) is the insectivorous bird?
Predators and prey
• Predators are animals that feed on other animals
called prey.
• Rosebush  aphid  ladybird  spider bird
The food chain above shows That the ladybird,spider
and the bird are all predators.
Question: Why isn’t the aphid considered a predator?
Ecosystem
• An ecosystem is a unique collection of animals
and the surroundings which they interact with
Ecosystem contains living and nonliving factors:
• An ecosystem consists of abiotic factors such
as the non-living environment, soil, air,
water,etc which the animals would not be able
to do without and biotic factors, or the
organsisms which live there.
• The abiotic factors are also called the habitat
or the area which provides a suitable
environment where an organism can live.
Niche’
• Each organism plays a specific role as part of
an ecosystem, E.g the robin below is an insect
hunter. It’s niche’ can be thought of as it;s job
description.
Describing animals
• All the animals of the same species occupying the
same geographical area are termed a population. E.g a
family of mice living in a barn, or a school of fish living
near a bank.
• Several populations of different species of animals
interacting together are termed a community.
• A log carries a few members of a species of snake from
a mainland to nearby island. Why are these 2 groups
not considered to be the same population?
Extinction