EcosystemsEcosystems

Learning Intention

• To be able to describe what is meant by a habitat, population, community and ecosystem.

Habitat• An organisms habitat is the place

where it lives.

Population• A population is all the members of

one species in an ecosystem.

Population of sea turtles

Population of dolphins

Community = all the plants and animals in a habitat

Water habitat

Example of an ecosystem:

Ecosystem = Community + Habitat

Learning Intention

• To be able to:– Give an example of a food chain.– Identify the producers, primary and

secondary consumers in a food chain.

What is a food chain?

Photosynthesis.........

What happens to the What happens to the food plants make in food plants make in

photosynthesis?photosynthesis?

Food Chains• Food chains show which organisms eat

other organisms

Grass Rabbit Fox

• The arrows show the transfer of energy from one organism to the next.

• It also helps to think of the arrows as meaning ‘is eaten by’.

• Producers - organisms which can make their own energy from carbon dioxide and water using sunlight for energy (plants)

Primary consumer - organisms which eat producers.

Secondary consumers - organisms which eat primary consumers.

Secondary consumers are predators

Arrange these into food chains

1. Lion, grass, Zebra2. Weasel, fieldmouse, owl, wheat3. Greenfly, oak leaf, thrush, ladybird4. Herring, animal plankton, human,

plant plankton5. Frog, hawk, grass, snake,

grasshopper

Learning Intention

• To be able to describe the path of energy flow in a food chain.

Energy loss• Some energy is lost at each stage in a food chain.

• Each organism in a food chain uses some of the energy to build up its body and grow.

• Most of the energy that organisms gain in a food chain is used up when the organism moves about, and in warm-blooded animals, to keep warm.

• This means that, as humans, it is more efficient for us, and we receive more energy from, eating plants.

Questions1. What is the source of energy entering a food

chain?

2. What does every food chain begin with?

3. Name two ways in which energy can be lost in a food chain.

3 things• Write down 3 things you know now

that you didn’t know at the start of the lesson.

• Once you have both finished, share them with the person beside you.

Learning Intention

• To be able to give an example of a food web.

What is a food web?• A food web is made up of 2 or more

food chains joined together.

• For example - – Grass Rabbit Fox– Grass Caterpillar Bird– Grass Beetle Mouse

Fox

Would make this food web

More complex food webs

Food Webs

Herb Live oak leaf Dead oak leaf

Greenfly Moth caterpillar

Earthworm Soil fungi

Ladybird Spider Vole

Small bird Owl The Food Web shown is from a typical woodland community.

Carnivores

Herbivores

Decomposers

Producers

Constructing a food webConsumer Food

Rabbit Oak, Primrose

Vole Primrose

Snail primrose

Frog snail

Weasel Vole, rabbit

Owl Vole

Hedgehog Snail, vole

Fox Frog, hedgehog, rabbit, weasel

Learning Intention

• Explain relationships between different organisms in a food web and effects of removing a species.

Questions

1. What will happen to the number of clown fish if the sharks become vegetarian?

2. What effect will this have on the number of zooplankton?3. What will happen to the Blue Regal fish if a disease wipes

out the small invertebrates.

Great White Shark

Clown Fish Sea Turtle

Algae

Blue Regal

Zooplankton

Small Invertebrates

Food Web

Learning Intention

• To be able to arrange organisms from a food chain into pyramids of number and biomass.

FOOD CHAIN

GRASS CRICKET FROG HAWK

1000 GRASS 100 CRICKETS! 10 FROGS! 1! PLANTS!

Discussion • What do you notice about the size of the actual

organisms as you move along a food chain?

• What do you notice about the number of organisms at each stage as you move along a food chain?

• Why do you think the number of organisms at each stage is changing?(Do big organisms eat the same amount as small organisms?)

Pyramids of Number• The relationship takes the form of a

pyramid because

– The energy loss at each link in the food chain limits the quantity of living matter that can be supported at the next level.

PYRAMID OF NUMBERS• Shows population size at each

stage in a food chain

1 HAWK

10FROGS

100CRICKETS

1000GRASS PLANTS

PROBLEM!!!!!

Can you explain the shape of this pyramid of numbers???

Choose one of the pyramids of numbers above to represent each of the three food chains below.

DANDELIONS RABBITS FOX FLEAS

PEAR TREE APHIDS LADYBIRDS PARTRIDGE

GREEN PLANTS SLUGS FROG FOX

Pyramids of biomass• The biomass of a population is the total mass of

living things.

• In a food chain the biomass of the producer is greater than the biomass of the primary consumer, which in turn is greater than that of the secondary consumer.

• Since biomass decreases at each level, it can also be represented as a pyramid shape.

Pyramid of Biomass

E.g. Oak tree Insects Birds

The pyramid of biomass shows the biomass of a population in an ecosystem.

Oak tree

Insects

Birds

A pyramid of biomass is always a true pyramid

shape.