Introduction All habitats on Earth are part of the biosphere. Since the Earth is always changing, ha

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Introduction All habitats on Earth are part of
the biosphere. Since the Earth is always
changing, habitats are continually evolving
(changing) as well. Humans have a major effect
on habitats. Things we do can increase or
decrease the number of certain species.
Descriptions of environment such as temperature
and rainfall are used to group habitats together.
Habitats of similar climate and vegetation are
called biomes.
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• EcosystemsAn Interactive World
• The world is filled with living things and
  nonliving things that are constantly interacting.
  An ecosystem is all the living and nonliving
  things in an area interacting with each other.
  Scientists study the activities of living things
  to see if and how the ecosystem stays healthy.

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• An ecosystem can be divided into two main parts

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• Whats Inside an Ecosystem?
• A population consists of all organisms of the
  same species in the same area. Scientists want
  to know how populations interactfor example,
  which animals prey on others, which animals eat
  plants, and which insects eat crops.
• A community consists of all the populations
  living in the same area.
  
• A habitat is any place where a particular animal
  or plant species lives. It can also be thought of
  as the environment or a species surroundings.
  Examples of a habitat include a lake, a stream,
  or even a drop of water.

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• Each species in an ecosystem also has a role or
  place in the activities of its community. A niche
  is the organisms role in the community.
  
• A species' niche includes many factors
• what a species eats and what eats that species
• kind of environment the species needs to live in
• whether the species is active by day or by night

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• How the Environment Changes
• The world is full of changes. Certain kinds of
  events can change an entire ecosystem. A
  hurricane may sweep over the area, ripping out
  trees. A volcano might erupt. This makes
  habitats change. A good habitat for a certain
  organism at one time may be a threatening one at
  another time.

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• These factors that cause changes to the
  environment include
  
• seasonal changes
• weather changes
• natural disasters
• human impact (problems caused by humans)
• Plants and animals adjust to changing habitats in
  many different ways. In order to survive, they
  may acquire special characteristics to live in
  their changed habitats. Characteristics that
  help an organism survive in its environment are
  called adaptations.

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• Who Eats Whom?
• Food Chains, Food Webs Energy Pyramids
• In order to survive, all living things depend on
  each other for energy.
  
• A food chain is shows how each living thing gets
  its food. Energy is lost as it passes from one
  organism to another in a food chain. For
  example, a simple food chain links the trees and
  shrubs, the giraffes (that eat trees and shrubs),
  and the lions (that eat the giraffes). Each link
  in this chain is food for the next link.

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To follow the path of food as it passes from one
organism to the other, read the arrow as
is eaten or consumed by
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• The first organisms in a food chain are plants.
  Plants capture solar energy during
  photosynthesis. This energy is stored in the
  foods the plant makes. When these plants and
  animals die they become food for organisms like
  worms and ants.

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• Every community includes organisms that compete
  for the same resources. This means that, in an
  ecosystem, many small food chains may overlap
  each other. A food web is the overlapping food
  chains in a community. A food web shows the
  relationship between all the species in a
  community. It includes producers, consumers, and
  decomposers.

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To follow the path of food as it passes from one
organism to another, read the arrow as
is eaten or consumed by
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• Food chains and food webs exist in all
  ecosystems.
  
• PRODUCERS
• The first organisms in a food chain/web are
  plants. Food chains and food webs all have
  producers. The producers on land include grasses
  and trees. Producers use the Sun's energy to
  produce their own food.
• CONSUMERS
• Organisms that cannot make their own food are
  consumers. They get energy from food made by
  other organisms. Consumers can be grouped
  according to the type of food they eat.

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• Primary consumers herbivores that consume
  primary producers, such as terrestrial (land)
  insects, grazing mammals, seed-eating birds,
  aquatic zooplankton, and some fish.
• Secondary consumers carnivores that eat
  herbivores, such as frogs, insects-eating birds,
  lions, and many fish
  
• Tertiary consumers carnivores that eat other
  carnivores.

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• DECOMPOSERS
• Every food chain ends with decomposers such as
  worms, bacteria, and fungi. Decomposers break
  down dead organisms and wastes into simpler
  molecules. Some of the molecules are returned to
  the soil.

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• HERBIVORES, CARNIVORES and OMNIVORES
• Herbivores are animals that eat plants and other
  producers. Herbivores may be as small as
  grasshoppers or as large as elephants.
  Herbivores, in turn, are eaten by
  carnivoresanimals that eat other animals. All
  cats, big and small, are carnivores. So are
  dogs, foxes, and other sharp-toothed animals. An
  animal that eats both animals and plants is an
  omnivore. You are an omnivore. Bears are
  omnivores, toothey eat foods ranging from
  berries to salmon.

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• PREDATORS, PREY and SCAVENGERS
• Living things that hunt other living things for
  food are called predators. The hunted are called
  prey. Not all meat eaters are predators. Some
  animals eat meat but don't hunt it. Such meat
  eaters are called scavengersthey feed on the
  remains of dead animals. Crows and vultures are
  scavengers.

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• ENERGY PYRAMIDS
• In a food chain, energy is passed from one link
  to another. When a consumer eats, only a fraction
  of the energy that it gets from its food source
  is passed on to the next consumer that eats it.
  The rest of the energy is lost as waste or used
  up by the consumer to carry out its life
  processes (e.g., movement, digestion,
  reproduction).
• In other words, a large number or producers and
  consumers at the base of the food chain/web are
  required to support a few consumers at the top of
  the food chain/web. For example, many herbivores
  are needed to support a few carnivores. A
  carnivore then has to eat many herbivores to get
  enough energy to grow.

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• Because of the large amount of energy that is
  lost at each link, the further along the food
  chain you go, the less food (and therefore
  energy) remains available.
• Most food chains have no more than four or five
  links.
  
• Most animals are part of more than one food chain
  and eat more than one kind of food in order to
  meet their food and energy requirements. These
  interconnected food chains form a food web.
• A change in the size of one population in a food
  chain will affect other populations.

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This interdependence of the populations
within a food chain helps to maintain
the balance of plant and animal
populations within a community.
For example When there are too many giraffes t
here will be insufficient trees/shrubs for all of
them to eat many giraffes will starve and die fe
wer giraffes means more time for the trees/shrubs
to grow fewer giraffes also mean less food is ava
ilable for the lions therefore, some lions will s
tarve to death fewer lions means the giraffe popu
lation will increase
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• Cycles of Life
• Earths systems recycle water, carbon and
  nitrogen.
  
• Water Cycle
• The water cycle is the movement of water between
  the Earths surface and the air changing from
  liquid to gas. The stages in the water cycle are
  evaporation, condensation, precipitation, and
  collection. Evaporation is when liquid changes to
  gas. Condensation is when gas changes into
  liquid. Precipitation is water falling to Earths
  surface in some form such as rain, sleet, snow,
  or hail.

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• Carbon Cycle
• The carbon cycle shows the transfer of carbon
  between the atmosphere and living things. Carbon
  is important because it is part of carbohydrates
  that the body uses for energy.

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• Nitrogen Cycle
• The way nitrogen moves between the air, soil,
  plants, and animals is called the nitrogen cycle.
  Animals get nitrogen from the proteins that we
  eat. Plants, animals, bacteria, and decomposers
  are all involved in recycling nitrogen. The air
  is 78 percent nitrogen.
• A dead tree can help living things. It can be
  decomposed so that it is a source of substances
  that living things can use. It can also provide
  shelter for some animals and plants. Decomposers
  can recycle nutrients by breaking down dead
  organisms into simpler substances that become
  part of the soil.
• It is important to recycle both renewable and
  nonrenewable resources because nonrenewable
  resources can be used up and renewable resources
  may take a long time to be replaced.

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