Eco-Schools Lesson Plan
Lesson title: MARINE FOOD CHAINS & FOOD WEBS
Key Stage: 2 (with extension activities for KS3)
Resources & Preparation:
1. Bookmark websites for pictures of marine mammals and marine life in
general. We suggest:
 Sea Watch Foundation Species Identification Guides (whales,
dolphins & porpoises):
http://www.seawatchfoundation.org.uk/speciesid.php
 For pictures of phytoplankton and zooplankton, you can use Google
Images or MarineBio: http://marinebio.org/oceans/forests/
In addition, Appendix 1 contains a selection of pictures of marine life that
students can copy or cut out.
2. Materials to make a food chain and food web: string/thread, sticks/straws,
paper/card, scissors, colouring pens, sticking tape.
Subjects: Science / Geography / Art & Design
Extension Activities: English / Science / ICT
Lesson Objectives:
Students will …
 learn generally about the interdependence of sunlight, plants and animals.
 learn specifically about the connections between marine plants and animals
by drawing or making a food chain and/or food web using a variety of
materials.
 educate others about food chains and food webs by talking about or
exhibiting their work.
Sperm whale. SWF/Peter Evans
Introduction:
 A food chain is “a feeding hierarchy in which organisms in an ecosystem are
grouped into nutritional (trophic) levels [that] are shown in a succession to
represent the flow of food energy and the feeding relationships between
them.”¹ Put simply, it is about what provides energy in the form of food for
what.

Within marine ecosystems marine mammals are often the predators at the top
of the food chain. The health of marine mammals in terms of the size of
populations and their distribution can reflect changes occurring further down
the food chain, for example, through over-fishing or pollution.

A food web is “many food chains linked together to show a more accurate
model of all possible feeding relationships of organisms in an ecosystem.”² By
mapping the connections between organisms, you can get a broader
understanding of a marine ecosystem and see how the health of one species,
for example, through over-fishing or hunting, can have many effects.
Activities (lesson plan):
1. Think about familiar food chains. Introduce the idea of food chains with
familiar examples. For instance, you can ask students if they drink milk. Then
ask where the milk comes from (a cow/sheep/goat) and what that animal eats
to get energy to produce milk. Cows eat plants, usually grasses and legumes
(clover, alfalfa, etc); they are herbivores. It would be useful here to introduce
the vocabulary ‘carnivore’ and ‘omnivore’. Finally, ask where the grass gets
its energy from – the sun in the form of sunlight. From these answers, you
can build up a diagram on the board showing the energy flowing up from the
grass to the human consumer and introduce the term ‘food chain’.
Alternatively, use sunshine / tree (apple) / human as a food chain.
2. Marine food chains. Since marine food chains may include plants and
animals that are unfamiliar to your students (see the glossary for simple
definitions), rather than eliciting the food chain you could write the names
randomly on the board, or put them onto cards, and, after explaining what the
unfamiliar organisms are, ask the students to arrange them in a food chain
with sunlight as the original energy source, for example:
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sunlight / algae / limpet / shore crab / otter;
sunlight / kelp / periwinkle / edible crab / bottlenose dolphin;
sunlight / phytoplankton / zooplankton /sand eel / mackerel / gannet;
sunlight / phytoplankton / zooplankton / fin whale;
sunlight / phytoplankton / krill / squid / sperm whale;
sunlight / phytoplankton / zooplankton / fish / seal / killer whale;
sunlight / phytoplankton / mussels / starfish / edible crab / bottlenose
dolphin;
sunlight / phytoplankton / basking shark;
sunlight / phytoplankton / zooplankton / jellyfish / leatherback turtle;
sunlight / phytoplankton / zooplankton / sand eels / herring / grey seal;
sunlight / algae / limpet / dog whelk / oystercatcher.
3. Make a food chain mobile. Students draw, colour and cut out pictures of the
organisms in their food chain. Then, tape the organisms to string or
embroidery thread with the sun at the top or bottom to represent the flow of
energy.
4. Introduce food webs. On the board begin another food chain:
sun/phytoplankton/zooplankton/fish/seal. Then stop and ask the students if
fish are only eaten by seals. Ask what other animals (mammals, birds) eat
fish. Use the answers to build up a more complex picture of the energy
interactions within the marine habitat. Include people into the web where
relevant.
5. Play the food web game. This game provides a clear and tactile
representation of how a food web is built and how it is affected by change. It
requires a large space, preferably outside. Give each student a card with a
different marine plant or animal on it. The student with the ‘sun’ card stands in
the middle. Give the ‘sun’ student a ball of wool or string. Read out one of the
example food chains, for example, sun / kelp / periwinkle / edible crab /
bottlenose dolphin. Each student who is called out wraps the wool around
herself or himself and passes it on. When the ‘food chain’ is finished, cut the
wool. Return the wool to the sun again and begin with a different food chain.
Repeat the process until all the chains have been completed. Once the food
web is formed, ask the students questions about the effects of a decline or
rise in one of the species. The students can pull the wool to see which other
species would be affected.
6. Make a marine mammal food web. Instead of, or in addition to, making a
food chain, the students can make a food web. The food web can take many
forms depending on the time and materials available: a drawing; a large
collage; a mobile using sticks or straws horizontally to represent the different
energy levels and tying thread between cut-outs to show connections; a
computer-made diagram. To be accurate, it would work best if the students
chose a particular area of the UK (perhaps the closest marine area to them)
and research the marine plants, birds and marine mammals living and
interacting there. The students should add humans to the food webs where
applicable.
7. Display the marine food chains and webs. The students can display the
completed marine food chains and/or webs in a place where other students or
people can see and learn from them, putting emphasis on how to portray the
information visually so that it is easy to understand.
8. Discuss effects of changes in the food chain or food web. Ask the
students questions that encourage them to think about the interdependence
of food chains and webs:
 Sunshine / phytoplankton / zooplankton / fish / seal / killer whale – in this
food chain what would happen if most of the fish were fished and eaten by
people or died from disease? What would happen if the number of seals
increased? If the phytoplankton absorbed (took in) pesticides (pollutants),
how might that affect the killer whales?
 Ask similar questions about the food chains or webs that the students
have made.
Extension activities:
 Make a species field guide. Students can make a short field guide about a
particular species from the food web. The guide would include: species name,
species scientific (Latin) name, colour drawing, its life expectancy, habitat,
diet and an interesting fact. The hand-written or ICT-produced field guides
can be placed near the food web collage/mobile for other students to read
and learn from. [English / Science / ICT ]
For Key Stage 3:
 Food Web Investigation – Students can do research on the over-fishing,
hunting or polluting of a particular species or region and investigate how it has
affected the food web of that organism or region. For instance, the dog whelk
(Nucella lapillus) was severely affected by pollution³. In the 1970s and 1980s
paint (TBT) used on the hulls of ships in the UK actually caused female dog
whelks, particularly around ports, to change sex and become male and the
population declined. The use of TBT is now controlled. How did this affect the
animals that the dog whelk preyed on and those that preyed upon the dog
whelk? [Science / Geography ]
Long-finned pilot whales. SWF/C. Swann
Curriculum Links:
Science
Sc2
Feeding relationships
Pupils should be taught:
5(d) to use food chains to show feeding relationships in a habitat;
(e) about how nearly all food chains start with a green plant.
Breadth of Study
2(a) use appropriate scientific language and terms … to communicate ideas and
explain the behaviour of living things.
Geography
Pupils should be taught to:
5(a) recognise how people can improve the environment or damage it, and how
decisions about places and environments affect the future quality of people’s lives;
(b) recognise how and why people may seek to manage environments sustainably,
and to identify opportunities for their own involvement [for example, taking part in a
local conservation project].
Art & Design
Pupils should be taught to:
1(b) question and make thoughtful observations about starting points and select
ideas to use in their work;
2(a) investigate and combine visual and tactile qualities of materials and processes
and to match these qualities to the purpose of the work;
3(a) compare ideas, methods and approaches in their own and others’ work and say
what they think and feel about them;
(b) adapt their work according to their views and describe how they might develop it
further.
Pupils should be taught about:
4(a) visual and tactile elements, including colour, pattern and texture, line and tone,
shape, form and space, and how these elements can be combined and organised for
different purposes.
Breadth of study
During the key stage, pupils should be taught the knowledge, skills and
understanding through:
5(b) working on their own, and collaborating with others, on projects in two and three
dimensions and on different scales.
Sources:
¹ http://www.biology-online.org/dictionary
² http://www.biology-online.org/dictionary
³ http://www.bbc.co.uk/nature/blueplanet/factfiles/molluscs/dog_whelk_bg.shtml
Glossary:
algae (noun) – a marine plant.
dog whelk (noun) – a carnivorous sea snail found on rocks on the sea-shore. It
feeds on limpets, mussels and barnacles.
kelp (noun) – a sort of seaweed; seaweed gets its energy from the sun.
krill (noun) – shrimp-like zooplankton.
limpet (noun) – a sea snail found on rocks on the sea-shore.
periwinkle (noun) – a small sea snail found on rocks on the sea-shore.
phytoplankton (noun) – tiny algae (marine plants) that live near the sea surface to
get energy for photosynthesis.
sand eel (noun) – a long, thin fish.
zooplankton (noun) – small organisms (animals), for example, early stages of
crustaceans and fish, that feed on phytoplankton. Zooplankton are eaten by small
fish.
Appendix 1
Pictures of marine organisms to copy
seaweed
mussel
periwinkle
starfish
oystercatcher
gannet
porpoise
limpet
jellyfish
crab
fish
herring gull
seal
dolphin