In ecology, energy flow, also called the calorific flow, refers to the flow of energy through a food chain. In an ecosystem, ecologists seek to quantify the relative importance of different component species and feeding relationships. A general energy flow scenario follows: Solar energy is fixed by the photoautotrophs, called primary producers, like green plants. Primary consumers absorb most of the stored energy in the plant through digestion, and transform it into the form of energy they need, such as adenosine triphosphate (ATP), through respiration. A part of the energy received by primary consumers, herbivores, is converted to body heat (an effect of respiration), which is radiated away and lost from the system. The loss of energy through body heat is far greater in warm-blooded animals, which must eat much more frequently than those that are cold-blooded. Energy loss also occurs in the expulsion of undigested food (egesta) by excretion or regurgitation. Secondary consumers, carnivores, then consume the primary consumers, although omnivores also consume primary producers. Energy that had been used by the primary consumers for growth and storage is thus absorbed into the secondary consumers through the process of digestion. As with primary consumers, secondary consumers convert this energy into a more suitable form (ATP) during respiration. Again, some energy is lost from the system, since energy which the primary consumers had used for respiration and regulation of body temperature cannot be utilised by the secondary consumers. Tertiary consumers, which may or may not be apex predators, then consume the secondary consumers, with some energy passed on and some lost, as with the lower levels of the food chain. A final link in the food chain are decomposers which break down the organic matter of the tertiary consumers (or whichever consumer is at the top of the chain) and release nutrients into the soil. They also break down plants, herbivores and carnivores that were not eaten by organisms higher on the food chain, as well as the undigested food that is excreted by herbivores and carnivores. Saprotrophic bacteria and fungi are decomposers, and play a pivotal role in the nitrogen and carbon cycles. The energy is passed on from trophic level to trophic level and each time about 90% of the energy is lost, with some being lost as heat into the environment (an effect of respiration) and some being lost as incompletely digested food (egesta). Therefore, primary consumers get about 10% of the energy produced by autotrophs, while secondary consumers get 1% and tertiary consumers get 0.1%. This means the top consumer of a food chain receives the least energy, as a lot of the food chain's energy has been lost between trophic levels. This loss of energy at each level limits typical food chains to only four to six links.

1. 1
Energy Flow
Through an
Ecosystem
Food Chains, Food Webs,Food Chains, Food Webs,
Energy PyramidsEnergy Pyramids

2. •Begins with theBegins with the
SUNSUN
•PhotosynthesisPhotosynthesis
6CO2 + 6H2O + sunlight & chlorophyll
C6H12O6 + 6O2

3. PhotosynthesisPhotosynthesis
•Chemical reaction where green plantsChemical reaction where green plants
useuse water & carbon dioxidewater & carbon dioxide to store theto store the
sun’s energy in glucosesun’s energy in glucose
•ENERGY is stored inENERGY is stored in glucoseglucose
•Glucose is stored asGlucose is stored as starchstarch in plantsin plants

4. 4
Organisms that canOrganisms that can
make glucose duringmake glucose during
photosynthesis arephotosynthesis are
calledcalled PRODUCERS.

5. 5
ProducersProducers useuse
most of themost of the
energy they makeenergy they make
for themselvesfor themselves..

6. 6
Producers useProducers use
cellular respirationcellular respiration
to supply theto supply the
energy they needenergy they need
to live.to live.

7. 7
CELLULARCELLULAR
RESPIRATIONRESPIRATION isis
the chemicalthe chemical
reaction thatreaction that
releases thereleases the
energy in glucoseenergy in glucose..
6O2 + C6H12O6 --> 6H2O + 6CO2 + energy

8. 8
TheThe energy that is notenergy that is not
used by producersused by producers cancan
be passed on tobe passed on to
organisms that cannotorganisms that cannot
make their ownmake their own
energy.energy.

9. 9
Organisms thatOrganisms that
cannot make theircannot make their
own energy are calledown energy are called
CONSUMERSCONSUMERS..

10. Consumers that eat producersConsumers that eat producers
to get energyto get energy::
•Are first order (1st
) or
primary consumers
•Are herbivores (plant-
eaters)

11. 11
MostMost of theof the
energy theenergy the
primary consumerprimary consumer
gets from thegets from the
producer isproducer is usedused
by the consumerby the consumer..

12. 12
SomeSome of theof the
energy moves intoenergy moves into
the atmosphere asthe atmosphere as
heatheat..

13. 13
Some energy in theSome energy in the
primary consumer isprimary consumer is
STOREDSTORED && not lostnot lost
to the atmosphere orto the atmosphere or
used by theused by the
consumer itself.consumer itself.
ThisThis energyenergy isis
availableavailable for anotherfor another
consumerconsumer (predator).(predator).

14. A Consumer that Eats AnotherA Consumer that Eats Another
Consumer for Energy:Consumer for Energy:
•Is called a secondary orIs called a secondary or
2nd order consumer2nd order consumer
•May be aMay be a carnivorecarnivore oror
aa omnivoreomnivore
•May be aMay be a predatorpredator
•May be aMay be a scavengerscavenger

15. 15
MostMost of theof the
energy theenergy the
secondarysecondary
consumer getsconsumer gets
from the primaryfrom the primary
consumer isconsumer is usedused
by the secondaryby the secondary
consumerconsumer..

16. 16
SomeSome of theof the
energy isenergy is lost aslost as
heatheat, but some, but some
energy is and canenergy is and can
passedpassed storedstored onon
to anotherto another
consumerconsumer..

17. A consumer that eats aA consumer that eats a
consumer that already ate aconsumer that already ate a
consumer:consumer:
•Is called aIs called a 3rd order3rd order
oror tertiary consumertertiary consumer
•May be aMay be a carnivore orcarnivore or
a omnivorea omnivore
•May be aMay be a predatorpredator
•May be aMay be a scavengerscavenger

18. Consumers that eat producersConsumers that eat producers
& other consumers& other consumers
Are calledAre called
omnivoresomnivores
OmnivoresOmnivores
eateat plantsplants
andand
animalsanimals

19. Consumers that hunt &Consumers that hunt &
kill other consumers arekill other consumers are
calledcalled predatorspredators..
The animals that areThe animals that are
hunted & killed arehunted & killed are
calledcalled preyprey..

20. Consumers that eatConsumers that eat
other dead consumersother dead consumers
are calledare called scavengersscavengers

21. 21
TheThe transfer of energytransfer of energy fromfrom
thethe sunsun toto producerproducer to primaryto primary
consumer then to higher orderconsumer then to higher order
consumersconsumers can be shown in acan be shown in a
FOOD CHAINFOOD CHAIN..

22. Food Chains Show Available EnergyFood Chains Show Available Energy

23. More Food ChainsMore Food Chains

24. 24
Another wayAnother way
of showing theof showing the
transfer oftransfer of
energy in anenergy in an
ecosystem isecosystem is
thethe
ENERGYENERGY
PYRAMIDPYRAMID

25. Energy Pyramids ShowEnergy Pyramids Show
•Amount of availableAmount of available
energyenergy decreasesdecreases forfor
higher consumershigher consumers
•Amount of availableAmount of available
energyenergy decreasesdecreases down thedown the
food chainfood chain
•It takes aIt takes a large numberlarge number
of producersof producers to support ato support a
small number of primarysmall number of primary
consumersconsumers
•It takes aIt takes a large numberlarge number
of primary consumersof primary consumers toto
support a small number ofsupport a small number of
secondary consumerssecondary consumers

27. Food Webs:Food Webs:
•AreAre
interconnectedinterconnected
food chainsfood chains
•They show theThey show the
feedingfeeding
relationships inrelationships in
an ecosysteman ecosystem

28. How Many Chains are in
this web?

29. Identify the Producers, Consumers, &Identify the Producers, Consumers, &
Decomposers:Decomposers:
Count theCount the
FoodFood
Chains!Chains!