Ecosystem Energy
Food Chains, Food Webs, & Ecological Pyramids What is Energy? •  The ability to do work •  It can exist in many forms: –  Light –  MoCon –  Electricity –  Heat –  Chemical –  Nuclear •  It is constantly changing form and is difficult to store Why Do Organisms Need Energy? •  To perform the basic funcCons of life: –  Growth & ReproducCon –  Gas exchange –  Waste eliminaCon –  Cell maintenance –  Respond to the environment •  These funcCons take place in every living cell, which are constantly working and using energy. Where Can Organisms Get Energy? •  Food! •  All organisms obtain energy from food, but they do so in two different ways: – Producers – make their own food – Consumers – eat other organisms •  Regardless, food is the source of chemical building blocks and energy required for life processes. Where Does Energy Come from? • All energy on Earth
originates from the
SUN!
• How?
Photosynthesis –The chemical process
by which producers make energy-rich
molecules from water and carbon
dioxide in the presence of sunlight.
•  We call the energy-­‐rich molecules, glucose, which are chemical building blocks required by life. •  The chemical reacCon is: 6CO2 + 6H2O + Sunlight à C6H12O6 + 6O2
Carbon dioxide + Water + Sunlight à Glucose + Oxygen
Chemical Building Blocks •  Are the maVer, or “stuff”, that provide our bodies with chemicals to repair and maintain cells. •  Consist of proteins, fats, carbohydrates, or nucleic acids •  The chemical bonds that hold them together release energy, which fuels the cells. Organisms that can make glucose (food) during photosynthesis are called PRODUCERS or AUTOTROPHS. Autotroph – self feeder These organisms create the biomass, or organic maVer, of an ecosystem Ex. Plants, algae, and phytoplankton Organisms that cannot make their own food are called CONSUMERS or HETEROTROPHS. Heterotroph = different feeder This means they have to eat others to obtain energy. There are many different types of heterotrophs An organism that eats a producer: •  Are called first order heterotrophs or primary consumers •  Are herbivores –  (plant-­‐eaters) An organism that eats a primary consumer: •  Is called a second order heterotroph or secondary consumer –  Carnivores or Omnivores An organism that eats a secondary consumer: •  Is called a third order heterotroph or terCary consumer Consumers that eat producers & other consumers •  Are called omnivores DetriCvores vs. Decomposers •  Feed on remains of •  Feed on detritus, dead organisms other known as dead •  Break down maVer material into r
ecyclable, •  Usually do not break simple chemicals to material into be reused by recyclable maVer producers •  Ex. Maggots, worms, •  Ex. Bacteria and beetle larvae decomposers Energy Flow through an Ecosystem •  Can be traced using the organisms’
feeding relationships
•  Scientists will group the organisms
one of three ways:
•  Food Chain
•  Food Web
•  Food Pyramid
Food Chains •  Show a sequence of organisms
that eat one another in an
ecosystem
•  Arrows are used to indicate
who obtains energy from
who.
•  Will always point to where
the energy is going
Food Webs: •  Are interconnected food chains •  They show all the feeding relaConships in an ecosystem –  Also use arrows to show energy paths Food Pyramids •  Represent trophic levels, or
feeding levels of an ecosystem in
terms of biomass
•  When in order from producers, to
primary consumers, secondary
consumers, tertiary etc. the result is
a layered pyramid
•  Each level has less biomass than
that below it.
Energy pyramids show •  That the amount of available energy decreases down the food chain (or up the pyramid) •  It takes a large number of producers to support a small number of primary consumers •  It takes a large number of primary consumers to support a small number of secondary consumers Why? For each feeding level, most of the energy obtained by each organism is used to complete life funcCons. This energy is burned up and “lost” to the environment in the form of heat. Any le] over energy is available for the next feeding level, but steadily decreases as you reach the top 10 % Rule •  The energy that passes through an ecosystem is o]en “lost” because organisms require most of what they eat to perform funcCons to live •  Only about 10% of the energy consumed by the organism is actually stored as biomass and available for the next feeding level Significance? •  The 10% rule shows that there will always be fewer predators than prey and fewer herbivores than plants, hence the pyramid shape. •  So much energy is lost between levels that consumers must eat a lot just to maintain their body mass and funcCons Decomposers and the Pyramid •  Usually are difficult to include because they feed from every level. •  ScienCsts usually put them on the side of the pyramid to show their role in the ecosystem. MaVer Vs. Energy in an Ecosystem •  Ma3er is recycled (by decomposers) into simple chemicals, like carbon dioxide, water, and minerals, and reused over and over again by the environment. •  Energy is never recycled!! It originates from the sun, passes from organism to organism, then it is lost as heat to life processes.