Download What is an Ecosystem? - Swampscott Middle School

What is an Ecosystem?
An ecosystem is made up of many different components.
The components of an ecosystem that are biotic, or related to life,
are the living factors in an ecosystem. Plants, animals, fungi, protists,
and bacteria are all biotic, or living, factors. The behaviors of living
organisms are also considered biotic factors. For example, when an
animal hunts and eats another organism (predation), this is a biotic
factor, because it involves living things. The role, or niche, an
organism plays in an ecosystem is also known as a biotic factor.
Think: BIOLOGY. This will help you remember that biotic factors are
living things and their behaviors.
Abiotic, meaning not alive, are the nonliving factors that affect the
organisms living in an ecosystem. Weather, temperature, moisture,
light, chemicals and certain components of soil are all examples of
abiotic factors present in many ecosystems.
These biotic and abiotic factors combine to create a system, or more
precisely, an ecosystem. An ecosystem is a community of living and
nonliving things often studied as a whole that is made up of many
parts.
ECOSYTEM = THE WHOLE (like a pie)
BIOTIC & ABIOTIC FACTORS = THE PARTS (like the crust, pan,
blueberries, sugar, and whipped cream)
Biotic and abiotic factors are interrelated. If one factor is
changed or removed, it impacts the availability of other
resources within the system. (Think about how different that pie
would be without the blueberries!)
BIG IDEA: An ecosystem is a basic unit in ecology, formed by the
interaction of plants, animals and microorganisms (biotic factors) with
their physical environment (abiotic factors).
A pond ecosystem refers to the freshwater ecosystem where there
are communities of organisms that are dependent upon each other
and the water environment in which they live, for their nutrients and
survival. Usually, ponds are shallow (hardly 12-15 feet) water bodies
in which sunlight can reach to the bottoms, permitting the growth of
the plants there.
The organisms (living things) inhabiting a pond ecosystem include
algae, fungi, microorganisms, plants, and a variety of vertebrate and
invertebrate animals. All of these organisms surviving together within
the ecosystem are called a community.
Each group of individual species of organism (for example, all the
rabbits or all the club fungi) is called a population.
BIG IDEA: Many populations living and surviving together form a
community.
Often, in an ecosystem, there are challenges facing each individual
species or population of organism. These challenges are called
limiting factors. Limiting factors can be in the form of biotic or
abiotic factors.
Here’s an example of a biotic limiting factor. Dragonfly larvae swim
around in the pond and eat lots of tadpoles. So, the dragonfly larvae,
as predators, are a limiting factor for the tadpole & frog population. In
other words, the dragonfly predation makes it difficult for the frog
species to live, grow, and reproduce.
What about an abiotic limiting factor? Think about a pond in the
winter. The temperature can drop very low, affecting how many of
the organisms live. Many of them stop growing and reproducing until
spring arrives. So, temperature can be an abiotic limiting factor that
affects many species in the pond.
BIG IDEA: A limiting factor is anything that tends to make it more
difficult for a species to live, grow, or reproduce in its environment
Food Chains and Webs
Do you like to play games? If you do, you will need energy. Every time you
run or jump, you are using up energy in your body. How do you get the
energy to play? You get energy from the food you eat. Similarly, all living
things get energy from their food so that they can move and grow. As food
passes through the body, some of it is digested. This process of digestion
releases energy.
A food chain shows how each living thing gets its food. Some animals eat
plants and some animals eat other animals. For example, a simple food
chain links the trees & shrubs, the giraffes (that eat trees & shrubs), and
the lions (that eat the giraffes). Each link in this chain is food for the next
link. A food chain always starts with plant life and ends with an animal.
Plants are called producers because they are able to use light energy
from the Sun to produce food (sugar) from carbon dioxide and
water.
Animals cannot make their own food so they must eat plants and/or other
animals. They are called consumers. There are three groups of
consumers.
Animals that eat ONLY PLANTS are called herbivores (or primary
consumers).
Animals that eat OTHER ANIMALS are called carnivores.*
Animals that eat both plants and animals are called omnivores.*
*Carnivores/omnivores that eat herbivores are called secondary
consumers. Carnivores/omnivores that eat other carnivores are called
tertiary consumers (for example, killer whales in an ocean food web).
phytoplankton → small fishes → seals → killer whales
Notice the direction of the arrows in the food chain above. The arrows
show the direction the energy is moving. The energy moves from the
phytoplankton to the fishes, then later to the seals, and finally, to the killer
whales.
Do you know why there are more herbivores than carnivores?
In a food chain, energy is passed from one link to another. When an
herbivore eats, only a fraction of the energy (that it gets from the plant
food) becomes new body mass; the rest of the energy is lost as waste or
used up by the herbivore to carry out its life processes (e.g., movement,
digestion, reproduction). Therefore, when the herbivore is eaten by a
carnivore, it passes only a small amount of total energy (that it has
received) to the carnivore. Of the energy transferred from the herbivore to
the carnivore, some energy will be "wasted" or "used up" by the carnivore.
The carnivore then has to eat many herbivores to get enough energy to
grow.
Because of the large amount of energy that is lost at each link, the amount
of energy that is transferred gets smaller and smaller
The further along the food chain you go, the less food (and hence
energy) remains available.
Most food chains have no more than four or five links. There cannot
be too many links in a single food chain because the animals at the end of
the chain would not get enough food (ENERGY) to stay alive. 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.