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The Biosphere
What is Ecology?
&
Energy Flow
Introduction
• Ecology = the study of interactions
among organisms and their
environment.
• Biosphere = Parts of the planet in which
all life exists.
– Land, water, air
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Levels of organization
• Species = a group of organisms that can
breed and produce fertile offspring.
• Population = groups of organisms that belong
to the same species and live in the same
area.
• Community = different populations that live
together in a defined area.
• Ecosystem = community of organisms
including their non-living physical
environment.
• Biome = group of ecosystems that have the
same climate and similar communities
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Energy Flow - Producers
• Autotrophs = plants, some algae and certain
bacteria capture energy and use that energy
to produce their own food.
– Plants = the primary autotrophs found on the land.
– Algae = The primary autotrophs found in aquatic
(water) environments such as oceans, lakes,
ponds.
– Cyanobacteria = photosynthetic bacteria found in
certain wet environments.
• Autotrophs are producers!
Energy Flow - Producers
• Photosynthesis =
process of using
energy in sunlight to
convert water and
carbon dioxide into
carbohydrates and
oxygen.
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Energy Flow - Producers
• Chemosynthesis =
When organisms use
chemical energy to
produce carbohydrates.
• Performed by many
types of bacteria
– Methanogens produce
methane.
– Halophiles live in high
salt water concentrations.
– Thermoacidophiles live in
acidic, sulfur rich, high
temperature
environments.
Energy Flow - Consumers
• Heterotrophs = organisms that rely on
other organisms for their energy and
food supply.
• Heterotrophs are consumers!
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Energy Flow - Consumers
• Herbivores = An organism that obtains
energy by eating plants.
• Carnivores = An organism that obtains
energy by eating other animals.
• Omnivores = An organism that eats
both plants and animals.
Energy Flow - Consumers
• Dentrivores = Organisms that feed of
dead and decaying animal or plant
material (detritus).
– Examples: earthworms, termites, slugs,
snails, maggots.
• Decomposers = Breaks down organic
matter into inorganic matter.
– Examples: fungi and bacteria.
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Feeding relationships - Food
Chains
• Food chain = A series of steps in which
organisms transfer energy by eating and
being eaten.
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Feeding relationships - Food
Webs
• Food web = links all of the food chains
in an ecosystem together.
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Feeding relationships - Food
Webs
• Each step in a food chain is called a
trophic level.
– 1st trophic level = producers
– 2nd, 3rd, 4th… trophic levels = Consumers
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Ecological Pyramids
• Ecological pyramid = diagram that
shows the relative amounts of energy or
matter contained within each trophic
level in a food chain or food web.
– Energy pyramid
– Biomass pyramid
– Pyramid of numbers
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Ecological Pyramids = Energy
Pyramid
• Only about 10% of the energy available
within one trophic level is transferred to
the next trophic level.
• Energy is used for respiration,
movement, reproduction.
• Some energy is lost as heat.
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Ecological Pyramids =
Biomass
• Biomass = Total amount of living tissue
within a given trophic level.
• Represents the amount of potential food
available for each trophic level.
• Expressed in grams.
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Ecological Pyramids =
Pyramid of Numbers
• Based on the numbers of individual
organisms.
• Not always shaped like a pyramid.
– Sometimes there are fewer producers than
there are consumers.
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