L5 and 6 Food Chains PDF

Food chains Food chains show feeding relationships between organisms and the flow of the energy through an ecosystem. A food chain shows how energy is transferred between organisms and “what gets eaten by what” Grass Grasshopper Mouse Snake Eagle The arrows indicate wh...

Food chains Food chains show feeding relationships between organisms and the flow of the energy through an ecosystem. A food chain shows how energy is transferred between organisms and “what gets eaten by what” Grass Grasshopper Mouse Snake Eagle The arrows indicate where the energy is going Food chains Food chains start with autotrophs - organisms which can photosynthesise like plants, algae or seaweed. They use energy from the sun to make their own ‘food’ These organisms are called “producers” – they “produce” the energy for the rest of the food chain through photosynthesis. Food chains The other organisms are all heterotrophs and eat other organisms as food. In a food chain they are called consumers. The primary consumer (or first order consumer) is the first consumer in the food chain. Then there are secondary, tertiary and sometimes quaternary consumers (or second order, third order consumers etc) Food chain Human Secondary Consumer Gains energy by eating primary consumers. Usually carnivores but can be omnivores Cow Primary Consumer Gains energy by eating producers. Usually herbivores Grass Producer Makes food from sun using photosynthesis  We can use several terms to describe the different organisms. Eg The grasshopper is a herbivore, a heterotroph, a primary consumer and prey of the snake The snake is a carnivore, heterotroph, secondary consumer, predator of the grasshopper, prey of the eagle  Trophic Top level carnivore 4 Trophic level Secondary consumer 3 Trophic level Primary consumer 2 Trophic level Producer 1  The top carnivore is the animal at the end of the food chain. Here the owl is the top carnivore But what happens to the energy in the owl when the owl dies?  Detritivores and decomposers will feed on the dead owl. These can be shown as the last part in a food chain. Sometimes the sun is shown as the first part of a food chain, as it is the initial source of energy  Food chains Food chains show feeding relationships between organisms and arrows are used to show the flow of the e________ through an ecosystem. Food chains start with ______trophs - plants, algae or seaweed. They use energy from the s___ to make their own ‘food’ These organisms are called “p___________” – they “produce” the energy for the rest of the food chain through ph________________. The other organisms are __________trophs and eat other organisms as food. In a food chain they are also called c_______________ The p__________ consumer is the first consumer in the food chain. Then there are s____________, t_______ and sometimes quaternary consumers. Each organism in a food chain is a t________ level. The producer is t________ level one. Sometimes d________ or d__________ are shown as the last organisms in a food chain and the s_____ is shown at the start. Draw food chains (words and arrows, no pictures) from the information below. Think carefully about the order of the animals and the direction that the arrow points: 1. Caterpillars are eaten by finches, which are eaten by owls. Caterpillars eat leaves. 2. Magpies eat crickets which eat grass. 3. Grasshoppers eat grass. Grasshoppers are eaten by rats. Hawks eat snakes, who eat rats. Food webs Food chains are quite simple and don’t tell the whole story. Animals often eat more than one type of organism and are part of different food chains. This makes sense because: Some food is not available all year round (seasons) Unable to get all nutrients required from one source We can better represent the feeding relationships in an ecosystem with a food web. Food Webs Describe how the blenny (a fish) occupies different trophic levels  The blenny is … A primary consumer when feeding on Fucus (brown seaweed) A secondary consumer when eating winkles A tertiary consumer when eating crabs Food webs - notes Animals often eat more than one type of organism and are part of different food chains. This is because: Some food is not available all year round eg birds can only eat some berries in certain seasons. It allows them to have alternative food sources to survive on if one source is scarce Animals are unlikely to get all the required nutrients (a balanced diet) from one food source We can better represent the feeding relationships in an ecosystem with a food web.  Use the following food web to answer these questions 1. write a food chain where the kingfisher is a secondary consumer (trophic level 3) 2. write a food chain where the kingfisher is a tertiary consumer (trophic level 4) 3. what eats a cricket? 4. what is the producer in the river? 5. what do red fins eat?  Use the following food web to answer these questions 1. write a food chain where the kingfisher is a secondary consumer (trophic level 3) Grass→ cricket → kingfisher (→ cat) 2. write a food chain where the kingfisher is a tertiary consumer (trophic level 4) Duckweed → (mayfly or yabby) → redfin → kingfisher 3. what eats a cricket? Lizard, cat, kingfisher 4. what is the producer in the river? duckweed 5. what do red fins eat? Mayflies, yabbies, worms  Use the following food web to 1. write a food chain where the kingfisher is a secondary consumer (trophic level 3) 2. write a food chain where the kingfisher is a tertiary consumer (trophic level 4)  Use the following food web to 1. write a food chain where the kingfisher is a secondary consumer (trophic level 3) Waterweed /algae → carp → kingfisher 2. write a food chain where the kingfisher is a tertiary consumer (trophic level 4) Waterweed /algae → prawn /carp → trout → kingfisher Constructing a food web Identify the producers Write the producers at the bottom Go through the paragraph and mark off each link in the paragraph as you write it down in the web When you get to the end of the paragraph check your web Construct a food web In a pond algae grows on rocks. The algae is eaten by tadpoles and crowfish. Dragonfly larvae eat tadpoles. Blue fish eat crowfish and dragonfly larvae. Spikefish prey on crowfish and blue fish. Herons eat all types of fish Construct a food web In the desert there are grasses and cacti. The grasses are consumed by mice. The cacti are eaten by crickets. Bats that live in a cave hunt both mice and crickets. Hawks eat mice and bats Construct a food web- extension In a particular forest ecosystem, leaf eating insects feed on the leaves of Eucalyptus trees, while sap-sucking insects feed on the sap of these trees. Starlings eat both types of insect, and these birds are in turn preyed upon by goshawks. Spiders that live in the trees feed on wasps and the leaf-eating and sap-sucking insects. The wasps are sometimes observed to eat the sap-sucking insects.  Constructing food webs: In a pond algae grows on rocks. The algae is eaten by tadpoles and crownfish. Dragonfly larvae eat tadpoles. Blue fish eat crownfish and dragonfly larvae. Spikefish prey on crownfish and blue fish. Herons eat all types of fish In the desert there are grasses and cacti. The grasses are consumed by mice. The cacti are eaten by crickets. Bats that live in a cave hunt both mice and crickets. Hawks eat mice and bats  Food webs Food webs contain many interlinking food chains… 1. If the crab population suddenly decreased: a) What would happen to the population of flat winkles? b) What would happen to the population of herring gulls? 2. What might happen to the population of seals if the population of algae increases? 3. What might happen to the population of sea urchins if the population of crabs decreases? What would happen if an animal or organism was “taken out” ? e.g take out the crab: 1) What would happen to the population of flat winkles? It would increase, because they are not getting eaten as much 2) What would happen to the population of herring gulls? It would decrease, because there is not as much food Consider the same food web: 1) What might happen to the population of seals if the population of algae increases? increase 2) What might happen to the population of sea urchins if the population of crabs decreases? decrease  What would happen to the food web if the…. 1. prawns numbers decreased due to overfishing 2. frog numbers decreased due to pollution 3. carp numbers decreased due to a fish parasite  Food chains and food webs 1. Use all three food chains to draw a food web. A grass rabbit fox B wheat field mouse fox C wheat field mouse cobra (snake) 2. Name the producers in the food web. 3. Name the primary consumers. 4. Name a secondary consumer. 5. If the field mice died, what would happen to the number of Cobras? Why would this happen? 6. If the field mice died, what might happen to the number of rabbits? Why might this happen? 1. What is the producer in this food web? 2. How many primary consumers are shown in this food web? 3. Is the small bird always a secondary consumer? 4. Aphids are often considered pests by humans. A gardener sprays an insecticide in their garden which kills aphid. Explain how this will affect the food chain.  1. How many animals in this food web are herbivores? 2. How many animals in this food web are omnivores? 3. How many animals in this food web are carnivores? 4. Is grass an autotroph or heterotroph? 5. Write a food chain that has 4 trophic levels. 6. Bilbies are endangered due to deforestation and hunting by feral cats and foxes. If bilbies become extinct a) why might the eagle population be unaffected? b) why might the eagle population decline?  Invent some questions for a partner about this food web  Invent some questions for a partner about this food web Energy in measures in Joules (J). At each stage in a food chain energy gets “lost”: 1000J 100J 10J Trophic Trophic Trophic level 1 level 2 level 3 Only around 10% of the energy from each organism is passed on to its consumer. Energy is “lost” at each trophic level. That’s why food chains only usually have 4 or 5 levels, and why there is always more prey than predators.  1000J 100J 10J Trophic Trophic Trophic level 1 level 2 level 3 Scientifically energy cannot be “lost” or created or destroyed, however, it is lost from the food chain because it does not end up as biomass in the next organism i.e. living tissue than can be eaten At each stage in a food chain energy gets “lost”: 1000J 100J 10J Trophic Trophic Trophic level 1 level 2 level 3 Why does the owl only get 10% of the energy available in the mouse that it eats? Where does 90% of the energy go between each trophic level? Berries → mountain water skink→ noisy miner bird → feral cat Think of reasons why all of the energy in the skink is not transferred into the bird. And why the energy in the bird is not all passed on to the cat. Where is the energy ‘lost’ along a food chain? Some of the energy in skink that is eaten by the bird is used by the bird to move and reproduce. None of this is used to make new biomass (cells eg muscle) which can be eaten by the next consumer- the cat. In mammals some of the energy is used to keep warm. Where is the energy ‘lost’ along a food chain? Not all parts of the organism are edible or digested eg bone, feathers, hair, and in plants, bark and roots. This dead zebra represents ‘100% energy’ but the vultures will only eat some of the flesh so only get don’t consume all of the available energy. The energy in the bones and fur is not passed on to the vultures. Where is the energy ‘lost’ along a food chain? Some energy containing material is lost in faeces and urine, lost through processes of egestion and excretion. Where is the energy ‘lost’ along a food chain? Decomposers like bacteria and fungi will feed on the remains of animals and animal waste so the energy does get passed on to them.  Energy transfers in food chains- notes Only around _____% of the energy from each organism eaten is passed on to its consumer. Energy is “lost” at each t________ level. That’s why food chains only usually have ____ or ___ levels, and why there are always more prey than predators. Scientifically energy cannot be “lost”, however it is lost from the food chain because it does not end up as b_________ in the next organism i.e. living tissue that can be eaten. Some of the energy in the material eaten is used by the consumer to keep w______, m______ and reproduce. None of this is used to make new biomass in the consumer which can be eaten by the next consumer, so the energy is ‘lost’ from the food chain. Another reason for energy ‘loss’ is not all parts of the consumed organism are e________ or d___________ eg bone, feathers, hair of animals and bark and roots of plants. Some energy containing material is lost in f______ and u_______. Detritivore Decomposer Autotroph Food web Food chain Primary consumer Carnivore Tertiary consumer Quaternary consumer Herbivore Heterotroph Trophic level Top carnivore Omnivore Producer Secondary consumer Food chain Simple linear diagram which shows energy transfer between organisms Food web More complex diagram which shows energy transfer between many organisms Producer Organisms (plants and algae) that make their own food via photosynthesis using light energy from the sun, also called autotrophs Primary consumer Organism that eats the producer, 2 nd in the food chain Secondary consumer Organism that eats the primary consumer Tertiary consumer Organism that eats the secondary consumer Quaternary consumer Organism that eats the tertiary consumer Decomposers Microorganisms like bacteria and fungi that bring about decay. Herbivore Organism that eats plants Carnivore Organism that eats animals Top carnivore Animal that comes at the end of the food chain Omnivore Organism that eats plants and animals Trophic level Stage of a food chain Autotroph Organisms (plants and algae) that make their own food via photosynthesis using light energy from the sun, also called producers Heterotroph Organism which must eat other organisms as food Detritivore Organism which feeds on dead and decaying animal and plant matter (detritus) eg earthworms and woodlice Ecology and interdependence key words Simple linear diagram which shows energy transfer between organisms More complex diagram which shows energy transfer between many organisms Organisms (plants and algae) that make their own food via photosynthesis using light energy from the sun, also called producers Organism that eats the producer, 2 nd in the food chain Organism which feeds on dead and decaying animal and plant matter (detritus) eg earthworms and woodlice Organism that eats the primary consumer Organism that eats the secondary consumer Organism that eats the tertiary consumer Microorganisms (bacteria and fungi) that bring about decay. They recycle nutrients. Organism that eats plants Organism that eats animals Organism which must eat other organisms as food Animal that comes at the end of the food chain Organism that eats plants and animals Stage of a food chain Organisms (plants and algae) that make their own food via photosynthesis using light energy from the sun, also called autotrophs