Food Chains, Food Webs, and Ecological Pyramids

Dr. Lavate Rajendra Ananda

Raje Ramrao Mahavidyalaya, Jath; Dist.- Sangli

Mb.: 9623420161

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bryoraj@gmail.com

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Charles Elton (1927), a British ecologist recognized the existence of food chain as�“A series of organisms arranged in a linear manner with repeated eating and being eaten ”

• A food chain is the simplest path that energy takes through an ecosystem.
• Energy enters from the sun.
• Each level in the transfer of energy is a trophic level.
• Organisms at each level use energy in cellular respiration and heat loss and store the rest.

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Food

• Food is the source of all metabolic energy of the organisms
• It is a mixture of complex organic compounds synthesized from the simpler molecules.
• Green Plans and some autotrophic bacteria are capable of synthesizing their own food by utilizing solar (light) energy

The 1^st Trophic Level

• Consists of primary producers (autotrophs).
• Primary producers include land plants and phytoplankton in aquatic environments.

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2^nd Trophic Level

• Consists of primary consumers (heterotrophs)
• Primary consumers that eat green plants are herbivores.
• Examples: grasshoppers, rabbits, zooplankton

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The 3^rd and Any Higher Trophic Level

• Consists of consumers.
• Carnivores and omnivores
• Examples: Humans, wolves, frogs, and minnows

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Food Chain

• In ecosystem, various living organisms (plants, animals and microbes) in a definite sequence, according to their food habits.
• Plants are producers which are eaten by herbivores, which in turn are eaten by carnivores.
• “The transfer of food energy from the source in plants through a series of organisms arranged in a linear manner with repeated eating is known as food chain”

Types of Food Chains

• 1. Grazing Food Chain
• 2. Parasitic Food Chain
• 3. Detritus Food Chain

1. Grazing Food Chain

• It starts from living green plants & goes to grazing herbivores to primary carnivores to secondary carnivores and so on
• Ecosystem with such food chains are directly dependent on solar radiations or an autotrophic energy capture which passes to herbivores.

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• Producers, utilize the radiant energy of sun which is transformed to chemical form, ATP during photosynthesis.
• Most of the ecosystems follow this type of food chain & from energy point of view are very important.
• Thus, much of the energy flow can be described in terms of trophic levels.

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Grazing Food Chain

FOOD CHAINS

The ____ is the ______________ for food chains.

is a sequence of feeding relationships describing ______

___________________.

source of energy

Food Chain:

grass

grass-

hopper

frog

snake

eagle

Keep in mind that the arrow tip always points towards the “eater”.

food

eater

Sun

FOOD CHAINS

they must

eat or “________” other organisms.

grass

grass-

hopper

frog

snake

eagle

They use the energy in

_______ to make their

own food

They form the _____ of all ________ food chains.

Since they _______ make their own food,

sunlight

cannot

consume

basis

terrestrial

through a process called _____________.

photosynthesis

Label and write descriptions on your food chain diagram.

There are different levels of consumers…..

FOOD CHAINS

It’s at the ___ of its food chain.

primary consumer

tertiary consumer

quaternary consumer

secondary consumer

grass

grass-

hopper

frog

snake

eagle

The ___ consumer in a food chain. It eats _________.

The ___ consumer in a food chain. It eats ________________.

The ___ consumer in a food chain. It eats __________________.

The ___ consumer in a food chain. It eats ________________.

1st

2nd

3rd

4th

producers

primary consumers

secondary consumers

tertiary consumers

any organism that is __________ by any other.

not hunted

top

There are different levels of consumers…..

FOOD CHAINS

is the ___________ and _____________ of dead organisms.

grass

grass-

hopper

frog

snake

eagle

All organisms eventually die and decompose.

are substances

needed for an organism’s

______ and _____.

detritus

decomposers

nutrients

Nutrients:

Detritus:

are organisms that ___

_______ and break it down into ________.

Decomposers:

waste matter

rotting remains

eat

nutrients

detritus

growth

repair

The cycle restarts.

FOOD CHAINS

that can perform _____________ to make their own food.

phytoplankton

zooplankton

small fish

larger fish

shark

killer whale

Marine food chains

start with microscopic

aquatic organisms called

_____________

Food chains can occur in _______ ecosystems.

phytoplankton

photosynthesis

aquatic

top carnivore

FOOD CHAINS

Here they found new types of _______

that could generate energy using the _______ found in the vents.

which were too deep for _______ to reach.

In the 1970s, scientists discovered deep sea _________________ in the ocean

Though most aquatic food chains start off with photosynthetic phytoplankton that get their energy from the sun, there are exceptions.

Food chains can occur in _______ ecosystems.

sulfides

aquatic

Hydrothermal Vent

How could a food

chain start without sunlight and photosynthesis?

hydrothermal vents

bacteria

sunlight

FOOD CHAINS

Bacteria in these vents form the basis of vent food chains in the same way as phytoplankton and plants do in other ecosystems.

Food chains can occur in _______ ecosystems.

aquatic

octopus

crab

chemo-autotrophic bacteria

primary

consumer

secondary

consumer

producer

HUMANS AND FOOD CHAINS

Where are humans on any food chain?

Since humans are not hunted for food by any other animal,

(well maybe not this)

?

this makes us

____________.

Count how many of these animals you’ve eaten in your life.

and since humans eat almost anything,

top carnivores

HUMANS AND FOOD CHAINS

Have you ever eaten one of these?

onion

lettuce

tomato

What is it made of?

wheat

cheese

beef

What food chains did you participate in when you ate this?

Humans are mainly _______ consumers because we eat a lot of _____.

so this makes us also _________ consumers.

When we eat animals, they are usually _________ ,

HUMANS AND FOOD CHAINS

primary

secondary

herbivores

plants

2. Parasitic Food Chain

• Different from normal predators (animal that eats other animals) pray food chains.
• The larger organisms (host) is a source of energy for the smaller organisms (parasites).
• Life cycle of parasites is complex.
• Food goes from large organisms to smaller ones without right killing as in case of predator.

3. Detritus Food Chain �(Detritus Latin= rubbed off)

• It goes from dead organic matter including metabolic wastes and exudates derived from organic food chain into saprophytic micro-organisms and then to organisms feeding on detritus (Saprophytic) and their predators (hunter). Such ecosystems are less dependent on direct solar radiant energy.
• The energy is not lost in ecosystem as a whole, rather it serves as a source of energy for a group of organisms called detritivores that are separate from the grazing food chain.

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FOOD CHAINS

is the ___________ and _____________ of dead organisms.

grass

grass-

hopper

frog

snake

eagle

All organisms eventually die and decompose.

are substances

needed for an organism’s

______ and _____.

detritus

decomposers

nutrients

Nutrients:

Detritus:

are organisms that ___

_______ and break it down into ________.

Decomposers:

waste matter

rotting remains

eat

nutrients

detritus

growth

repair

The cycle restarts.

FOOD WEBS: represents may interconnected food chains describing various paths that energy takes through an ecosystem.�

No ecosystem is only made up of only one food chain.

Members of one food chain usually also belong to another.

When you put all the _____________ food chains in an ecosystem together, you form a ________.

food web

interconnecting

TROPHIC LEVELS

On land, the first trophic level begins with ______.

Each ___ in the chain represents one trophic level.

In the water, the first trophic level begins with _____________.

Trophic Level:

It is the _______ an organism occupies in a food chain.

position

link

phytoplankton

plants

TROPHIC LEVELS

3^rd trophic level

4^th trophic level

5^th trophic level

1^st trophic level

Each ___ in the chain represents one trophic level.

Trophic Level:

It is the _______ an organism occupies in a food chain.

position

link

2^nd trophic level

TROPHIC LEVELS

This 10 % is used to build _______

However, as energy is moved from one trophic level to the next, only ___ % of the energy makes it to the next level.

grass

grass-

hopper

frog

snake

eagle

As organisms eat one another, ______ is transferred up the food chain.

biomass

energy

10

This means that ___% of the energy is lost,

1000 kcal

100 kcal

10 kcal

1 kcal

0.1 kcal

- 900 kcal

- 90 kcal

- 9 kcal

- 0.9 kcal

90

as well as to fuel ______________.

bodily functions

mostly in the form of _______

and as ____ from metabolic processes.

detritus

heat

Ecological Pyramids

• Models that show how energy flows through ecosystems.
• Pyramids can show the relative amounts of energy, biomass, or numbers of organisms at each trophic level in an ecosystem.
• The base of the pyramid represents producers.
• Each step up represents a different level of consumer.
• The number of trophic levels in the pyramid is determined by the number of organisms in the chain or web.

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Energy pyramids compare energy used by producers and other organisms on trophic levels.�These are diagrams that represent each trophic level according to its energy, biomass, or population.

• Between each tier of an energy pyramid, up to 90 percent of the energy is lost into the atmosphere as heat.
• Only 10 percent of the energy at each tier is transferred from one trophic level to the next.

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ECOLOGICAL PYRAMIDS

The amount of energy always decreases as you move up trophic levels.

1) Pyramid of Energy:

This pyramid indicates the amount of Energy that is present in each trophic level.

Total energy

present in

tertiary

consumers.

Total energy

present in

secondary consumers.

Total energy present in primary consumers.

Total energy present in producers.

ECOLOGICAL PYRAMIDS

1) Pyramid of Energy:

The amount of energy always decreases as you move up trophic levels.

This pyramid indicates the amount of energy that is present in each trophic level.

Other pyramid models illustrate an ecosystem’s biomass and distribution of organisms.

• Biomass is a measure of the total dry mass of organisms in a given area.

Biomass pyramid

ECOLOGICAL PYRAMIDS

On land, the amount of biomass _________ as you move up trophic levels.

decreases

2) Pyramid of Biomass:

This pyramid indicates the amount of _______ that is present in each trophic level, in a given area.

biomass

Biomass is the amount of

_________ (without water) within organisms.

dry matter

Total biomass

present in

tertiary

consumers.

Total biomass

present in

secondary consumers.

Total biomass present in primary consumers.

Total biomass present in producers.

ECOLOGICAL PYRAMIDS

2) Pyramid of Biomass:

On land, the amount of biomass _________ as you move up trophic levels.

decreases

This pyramid indicates the amount of _______ that is present in each trophic level, in a given area.

biomass

Biomass is the amount of

_________ (without water) within organisms.

dry matter

ECOLOGICAL PYRAMIDS

In the water, the amount of biomass increase as you move up trophic levels, creating an inverted pyramid.

2) Pyramid of Biomass:

This is only possible because the reproductive rate of the organisms increases as you go down trophic levels.

Total biomass present in phytoplankton.

Total biomass present in primary consumers.

Total biomass present in

secondary consumers.

Total biomass present in

tertiary consumers.

ECOLOGICAL PYRAMIDS

2) Pyramid of Biomass:

In the water, the amount of biomass ________ as you move up trophic levels,

increases

This is only possible because the reproductive rate of the organisms ________ as you go down trophic levels.

increases

inverted

creating an

_______ pyramid.

• Even though a biomass pyramid shows the total mass of organisms at each level, it doesn’t necessarily represent the amount of energy available at each level.
• For example, the skeleton and beak of a bird will contribute to the biomass but aren’t available for energy.

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• A pyramid of numbers shows the numbers of individual organisms at each trophic level in an ecosystem.

• A vast number of producers are required to support even a few top level consumers.

ECOLOGICAL PYRAMIDS

and are _____ in number than the primary consumers,

However, when the producers are ____ ,

These are diagrams that represent each

Ecological Pyramids:

trophic level according to its ______ , _______ or _________.

population

biomass

energy

Total population

of producers.

Total population

of tertiary

consumers.

large

fewer

Give an example of the kind of producers that would result in this type of pyramid.

Total population of

secondary consumers.

Total population of primary consumers.

the pyramid looks like this.

3) Pyramid of Numbers:

ECOLOGICAL PYRAMIDS

These are diagrams that represent each

Ecological Pyramids:

trophic level according to its ______ , _______ or _________.

population

biomass

energy

Give an example of the kind of producers that would result in this type of pyramid.

and are _____ in number than the primary consumers,

However, when the producers are ____ ,

large

fewer

the pyramid looks like this.

3) Pyramid of Numbers: