PYRAMIDS OF : ENERGY, BIOMASS & NUMBERS

Summary

In 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

• 🌿 Ecological Pyramids are tools used to compare quantifiable biological variables such as energy, biomass, and numbers between trophic levels in an ecosystem.
• 🔍 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).
• ⏳ Energy decreases along the food chain due to organisms using some of it for their own functions, such as growth, development, and reproduction.
• 📉 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.
• 🌱 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.
• 🐟 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.
• 📊 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.
• 📈 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.
• 📚 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.
• 🌐 The lesson concludes with a reminder of the importance of the viewer's strength and a note of appreciation for watching the educational content.
• 👋 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

00:00

🌿 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.

05:02

🔋 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.

🌱 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.

📊 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.

👋 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 types—energy, biomass, and numbers—each providing insight into the structure and function of ecosystems. He encourages viewers to stay safe until the next lesson.

Keywords

💡Ecological Pyramids

Ecological pyramids are graphical representations used to compare the quantifiable biological variables such as energy, biomass, and numbers across different trophic levels in an ecosystem. In the script, ecological pyramids are the central theme, with the video focusing on explaining how these pyramids illustrate the decrease in energy and biomass as one moves up the food chain, from producers to consumers.

💡Trophic Levels

Trophic levels are the positions that organisms occupy in a food chain, with each level representing a different stage of consumption and energy transfer. The script explains that ecological pyramids compare these levels, starting from producers like plants up to top-level consumers like birds or sharks in the aquatic example provided.

💡Energy

In the context of ecological pyramids, energy refers to the amount of energy available at each trophic level, which is transferred from one organism to another in a food chain. The script notes that energy decreases as it moves up the food chain, with only about 10% of the energy being passed on to the next level, illustrating the concept with a hypothetical example involving cabbage, caterpillars, and birds.

💡Biomass

Biomass in the script represents the total mass of organic material present for a given species or group of organisms at a particular trophic level. It is used in the pyramid of biomass to show the decrease in the amount of organic material as one moves up the food chain, with producers typically having greater biomass than consumers.

💡Numbers

Numbers in the script refer to the population size or the count of organisms at each trophic level. The pyramid of numbers is used to illustrate the relative abundance of organisms, which typically decreases as one moves up the food chain from producers to top consumers, as exemplified by the script's food chain starting with 18 cabbages, eight caterpillars, and two birds.

💡Food Chain

A food chain is a linear sequence of organisms through which nutrients and energy flow, starting from producers and moving up to various levels of consumers. The script uses a simple food chain involving cabbage, caterpillars, and birds to illustrate how ecological pyramids are constructed and to highlight the decrease in energy, biomass, and numbers at each trophic level.

💡Producers

Producers are organisms that produce their own food, typically through the process of photosynthesis. In the script, the cabbage is used as an example of a producer, which captures energy from the sun and converts it into biomass, serving as the base of the food chain and ecological pyramids.

💡Consumers

Consumers are organisms that feed on other organisms. The script distinguishes between different types of consumers: primary consumers (herbivores like caterpillars that eat producers) and secondary consumers (carnivores like birds that eat herbivores), which are essential components of the food chain and the ecological pyramids.

💡Inverted Pyramid of Biomass

An inverted pyramid of biomass is a special case where the biomass increases as one moves up the food chain, typically found in aquatic ecosystems. The script provides an example of this with phytoplankton (producers), zooplankton, small fish, and larger predators like sharks, showing a unique case where the biomass pyramid is upside down compared to the typical pattern.

💡Energy Transfer Efficiency

Energy transfer efficiency refers to the percentage of energy that is passed from one trophic level to the next. The script mentions that energy decreases by approximately 90% as it moves up the food chain, with only about 10% of the initial energy being available to the next level, highlighting the inefficiency of energy transfer in ecosystems.

💡Herbivores

Herbivores are primary consumers that feed on producers, specifically plants. In the script, caterpillars are used as an example of herbivores, which eat the cabbage (producer) and are part of the energy and biomass transfer process depicted in the ecological pyramids.

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