PYRAMIDS OF : ENERGY, BIOMASS & NUMBERS
Summary
TLDRIn this lesson by Mr. Knight, ecological pyramids are discussed, focusing on comparisons between trophic levels in ecosystems. The variables examined include energy, biomass, and numbers. The lesson explains how energy decreases along the food chain, using an example with cabbage, caterpillars, and birds. It also covers pyramids of biomass, noting that biomass typically decreases up the food chain, except in aquatic ecosystems where it can be inverted. Lastly, the pyramid of numbers is illustrated, emphasizing how the number of organisms typically decreases as you move up trophic levels. The lesson concludes with a reminder of the importance of understanding these ecological concepts.
Takeaways
- πΏ Ecological Pyramids are tools used to compare quantifiable biological variables such as energy, biomass, and numbers between trophic levels in an ecosystem.
- π The script provides an example of a simple food chain involving three trophic levels: a producer (cabbage), a primary consumer (caterpillars), and a secondary consumer (birds).
- β³ Energy decreases along the food chain due to organisms using some of it for their own functions, such as growth, development, and reproduction.
- π The Pyramid of Energy illustrates the loss of energy at each trophic level, typically around 90%, leaving only about 10% to be passed on to the next level.
- π± Biomass, which is the organic material that can be used as energy or fuel, also decreases along the food chain, with producers generally having more biomass than consumers.
- π An exception to the typical biomass pyramid is seen in aquatic ecosystems where biomass can increase along the food chain due to the small size of primary producers like phytoplankton.
- π The Pyramid of Numbers represents the quantity of organisms at each trophic level, often starting with a larger base of producers and decreasing as one moves up the chain.
- π The shape of the Pyramid of Numbers can vary depending on the numbers provided for each trophic level, but it typically has an upward shape with a larger base.
- π The script emphasizes the importance of remembering and using the specific numbers provided in an example or an examination context to draw the pyramids accurately.
- π The lesson concludes with a reminder of the importance of the viewer's strength and a note of appreciation for watching the educational content.
- π The instructor, Mr. Knight, signs off with a message of safety and a promise to continue the lessons in the future.
Q & A
What are ecological pyramids used for?
-Ecological pyramids are used to compare quantifiable biological variables between trophic levels in an ecosystem.
What are the three variables that ecological pyramids focus on?
-The three variables that ecological pyramids focus on are energy, biomass, and numbers.
What is an example of a food chain provided in the script?
-The example of a food chain provided in the script involves three trophic levels: a producer (cabbage), a primary consumer (eight caterpillars), and a secondary consumer (two birds).
Why does energy decrease along the food chain?
-Energy decreases along the food chain because each organism uses some of the energy for its own functions such as growth, development, reproduction, and other living functions.
How much energy is typically passed on from one trophic level to the next?
-In a typical situation, only about 10 percent of the energy is passed on from one trophic level to the next.
What is the relationship between biomass and the food chain?
-The pyramid of biomass is similar to that of energy because biomass consists of organic materials that can be used as energy or fuel. Typically, the biomass of producers is greater than that of consumers.
Why is the pyramid of biomass in an aquatic ecosystem inverted?
-The pyramid of biomass in an aquatic ecosystem is inverted because the producers are microscopic, and the organisms get larger as you go up the food chain, leading to an increase in biomass along the food chain.
What determines the shape of the pyramid of numbers?
-The shape of the pyramid of numbers is determined by the number of organisms at each trophic level. The relative size of the box in the pyramid is drawn according to these numbers.
What is a typical shape for a pyramid of numbers in an ecosystem?
-A typical pyramid of numbers has an upward shape starting from a larger base and decreasing as you go up, reflecting that there are usually more producers than consumers.
What does the script suggest is the strength of an individual?
-The script suggests that an individual's strength is as great as they will make it, implying that personal strength is a result of one's own efforts and determination.
What is the closing remark from the script to the viewers?
-The closing remark from the script is a reminder for viewers to stay safe until the next lesson.
Outlines
πΏ Introduction to Ecological Pyramids
In this introductory lesson, Mr. Knight explains the concept of ecological pyramids, which are used to compare quantifiable biological variables between trophic levels in an ecosystem. The focus is on energy, biomass, and numbers. An example food chain is introduced, consisting of cabbage, caterpillars, and birds. The importance of remembering the numbers of organisms at each trophic level is emphasized, as these will be referred to later in the lesson.
π Pyramid of Energy
The pyramid of energy shows how energy decreases along the food chain because each organism uses some energy for its functions. For example, if cabbage starts with 1000 kilojoules of energy, only 100 kilojoules will be available to caterpillars, and 10 kilojoules to birds. This is because energy decreases by approximately 90% at each trophic level, used up by the organisms for growth, development, reproduction, and other functions.
π± Pyramid of Biomass
The pyramid of biomass is similar to the pyramid of energy, as it represents the total mass of living material at each trophic level. Typically, producers have a greater biomass than consumers. For instance, 3 kilograms of cabbage might support 1 kilogram of caterpillars and 0.75 kilograms of birds. An inverted pyramid of biomass can occur in aquatic ecosystems, where microscopic phytoplankton (producers) are outweighed by larger zooplankton, small fish, and larger fish like sharks.
π Pyramid of Numbers
The pyramid of numbers represents the count of organisms at each trophic level. In a provided example, 1 producer (cabbage) supports 8 caterpillars (herbivores), which in turn support 2 birds. Exam questions often provide specific numbers, and the shape of the pyramid must reflect these counts. Typically, the base of the pyramid (producers) is wider, tapering off at higher trophic levels (consumers), illustrating the decrease in organism numbers as energy flows up the food chain.
π Conclusion and Reminder
Mr. Knight concludes the lesson by appreciating the viewers and reminding them of the key takeaway: the strength lies in their will to learn. He emphasizes the importance of understanding ecological pyramids and their various typesβenergy, biomass, and numbersβeach providing insight into the structure and function of ecosystems. He encourages viewers to stay safe until the next lesson.
Mindmap
Keywords
π‘Ecological Pyramids
π‘Trophic Levels
π‘Energy
π‘Biomass
π‘Numbers
π‘Food Chain
π‘Producers
π‘Consumers
π‘Inverted Pyramid of Biomass
π‘Energy Transfer Efficiency
π‘Herbivores
Highlights
Introduction to ecological pyramids and their purpose in comparing trophic levels within an ecosystem.
Definition of ecological pyramids: used to compare quantifiable biological variables between trophic levels.
Focus on three variables in ecological pyramids: energy, biomass, and numbers.
Example of a food chain with three trophic levels: producer (cabbage), caterpillars, and birds.
Explanation of energy decrease along the food chain, approximately 10% energy transfer between trophic levels.
Detailed breakdown of energy transfer: 1000 kJ available to cabbage, 100 kJ to caterpillars, and 10 kJ to birds.
Introduction to pyramid of biomass: measures organic materials that can be used as energy or fuel.
Typical pyramid of biomass: producers have greater biomass than consumers, and biomass decreases up the food chain.
Example of biomass distribution: 3 kg of cabbage, 1 kg of caterpillars, and 0.75 kg of birds.
Special example of an inverted pyramid of biomass in aquatic ecosystems.
Explanation of inverted pyramid in aquatic ecosystems: microscopic producers and larger consumers.
Introduction to pyramid of numbers: illustrates the number of organisms at each trophic level.
Example of pyramid of numbers: 1 producer, 8 herbivores, and 2 final consumers.
Typical shape of pyramid of numbers: larger base with producers, decreasing numbers of consumers.
Emphasis on following provided numbers for exam purposes to accurately represent pyramid shapes.
Conclusion with appreciation for the lesson and motivational note to stay safe.
Transcripts
hello and welcome back mr knight here
with you again
for another lesson in today's lesson
we're going to focus on ecological
pyramids
now once you talk about ecological
pyramids you're
ultimately talking about a comparison
between trophic levels within an
ecosystem
now let us give a definition for
ecological pyramids now ecological
pyramids are used to compare
quantifiable
biological variables between trophic
levels
in an ecosystem now these variables that
we're going to focus on today
will include energy biomass
and numbers
before i get into the lesson or the
examples of these pyramids what i want
to look at
is an example of a food chain
so this sample food chain only involves
three types of organisms or three
trophic levels and so our producer
will be only one for this example we're
going to use eight caterpillars
and two birds now i want you to remember
these numbers
because i'm going to refer to these
numbers
later in the lesson now let's look at
our pyramid of energy
the first thing i wanted to note is that
energy decreases
along the food chain the reason
why energy decreases along the food
chain is because
each organism will use
some of the energy for its own
functions and so the cabbage for example
will use energy for growth development
reproduction
similarly to the animals they will use
some of the energy
as well and the animals will use energy
for
movement growth development reproduction
and
any living functions
and so let's remind you know quickly
[Music]
that along the food chain energy
decreases approximately
10 percent so let's say for example we
started out with a
thousand kilojoules of energy available
to the cabbage
10 will pass on to the
caterpillars and so we only have a 100
kilojoules of energy
and for the bird it will be only 10
kilojoules of energy
available now
let's look at the pyramid of biomass now
pyramid of biomass is similar to that of
energy
because biomass is the
organic materials that can be used
as energy or fuel and in a typical
situation
the producers will be greater than the
consumer
so consumers will always be less in
number
in fact going up the food chain the
number of organisms
typically decrease and so what is
producing the energy should be greater
than what is
consuming the energy all right
and so let's take for example just for
example
we have three kilograms of cabbage
we might have one kilogram of
caterpillar in total biomass
and we may have say less than one so
let's take for example 0.75 kilograms
in biomass for the bird now i want to
give a special example
of a special type of pyramid of biomass
and this example
is for an aquatic ecosystem
now the biomass will will increase
along the food chain and the reason for
this is because
the producer will be microscopic and the
organism will get larger as you go along
the food chain
now this type of pyramid is inverted
and so what we'll have in this aquatic
environment we might have
phytoplankton there those are the
producers
and we might have zooplankton and then
we have
small fish and of course if you go
larger than this small fish
then you have like larger fish for
example
shark all right and so let's now jump
into our pyramid of numbers so remember
this sample food chain we started out
with one
eight and then two now i want this
i want you to pay special attention
right here because the numbers are
critical
so you start with the producer one the
herbivore will be eight
for this sample and then the final
organism will be two now what i wanted
to make note of in that
in a given situation for exam purposes
for example
they will the examiner will provide you
with the numbers
that they want you to work with now
based on the numbers
your shape of the shape of the pyramid
of numbers
might be different okay so what you need
to focus on
is the number of organisms given at each
level and you draw your your relative
size of box
according to those numbers now in a
typical situation
what we will have is a pyramid shaping
like this
so let's say we have 20 cabbage in a
typical situation
um seven rats for example and two
cats and so typically
a pyramid of numbers will have this
shape
upward shape starting from a larger base
and decrease as you go up because of
course what is producing energy
typically is greater than what is what
consuming the energy
and hence this is a typical shape for a
pyramid of
numbers and so we're at the end of the
lesson at this time and i want to tell
you that i truly appreciate you watching
these
lessons and i want to remind you that
your strength
is as great as you will so until next
time
stay safe
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