Download Teachers` Notes

Nature’s Lights – Teachers’ Notes
Who is it for?
7-11 year olds
How long will it take?
The activity is ideal as a 1-2 hour session
Learning outcomes:
Students will learn how light is essential in order to see
things, and how and why animals that live in the dark
produce light via bioluminescence so that they can find
food and communicate with others.
Curriculum requirement:
This activity is designed to support the teaching of Key
Stage 2: Light: recognising that light is needed in order to
see things and that dark is the absence of light.
What do you need?
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Images of different organisms that produce
bioluminescence (available in the activity pack to
download)
Lights – these can be torches, tea lights, or even glow
sticks
Firefly flashcards – 3 different types, one needed for each
group, each with the unique code for that species, with a
series of dots and dashes (available to download)
Prey cards (available to download)
Preparation guidelines:
1) Read through the Teachers’ Notes and download the Activity Pack, which
provides resources such as images and flashcards.
2) Gather together the required materials, print out the images or put them into
a presentation.
How to run the session:
1) Find out what the students already know about light and how we see things.
Discuss how we need light in order to see things and that dark is the absence
of light.
2) Discuss how we might be able to see things if it is dark (e.g. turn on a house
light, use a torch, light a bonfire).
3) Ask the pupils how animals might be able to ‘turn on a light’ and introduce
the topic of bioluminescence (see background information below for more
information).
4) Introduce the first exercise: looking at pictures of different organisms that are
able to produce light. Arkive’s page on bioluminescence may be helpful for
this: www.arkive.org/c/bioluminescence
5) Run the second exercise: Firefly Communication
6) Run the third exercise: Foraging Flashlight Fish
7) Discuss the difficulties encountered during the exercises and how animals
might overcome these.
Background information:
Bioluminescence is light that is produced when a chemical reaction occurs within a
living organism. It can be particularly useful to animals that live in dark areas where
they need to make their own light to find food, find mates and to communicate with
each other.
Bioluminescent organisms are mostly found in the deep sea below depths of 1,000
metres, where there is no light from the sun, although a smaller amount are found in
shallower water and at the water’s surface, as well as on land. On land,
bioluminescence is rare and is only found in a few insects, including fireflies, click
beetles, worms and centipedes, as well as over 80 fungi species.
The colour and patterns of bioluminescent light vary greatly between species and
are often a reflection of the habitat in which an individual is found. Bioluminescence
occurs in many patterns and sequences and can be a light that glows continuously,
such as that seen in the foxfire fungus, or flashing, as with fireflies, or can form
mesmerising light displays across the entire body of the individual, as seen in squid.
Most frequently, light is usually produced in flashes that last between 0.1 and 10
seconds and occurs in localised areas on the body.
Bioluminescence can be used for hunting (or attracting) prey, making prey visible,
counter-illumination (camouflage), defence, finding a mate and communication,
and many species use light for more than one of these purposes.
Notes for Exercise 1: Organisms and their Environments
Look at the photos of different organisms that use bioluminescence and think about
the following questions for each one:
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What features do all the environments in which these animals live share?
(Answers might include: they are all dark)
Why is it dark? (Answers might include: light is unable to pass through so much
water – at 1,000 metres deep there is no light from the sun)
What are some of the challenges of living in the dark? (Answers might
include: difficult to find food / find a mate / communicate)
What would be the benefits of being able to produce light? (Answers might
include: help them to see things/food/mates)
What do you think the reason is that each of the species on the cards have
their own light? (Answers might include: flashlight fish being able to see their
prey, fireflies to communicate)
What might be some drawbacks of being able to produce your own light?
(Answers might include: being seen by predators)
Background information on the images:
Image 1: Flashlight fish
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‘Flashlight’ or ‘lantern’ fish and are mainly found in the Indo-Pacific in clear,
tropical water.
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They have light-producing organs beneath their eyes which contain
bioluminescent bacteria. They make use of the bacteria’s light in a symbiotic
relationship.
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The fish hide in caves during the day and emerge at night to feed. The lights
below their eyes are the only part of their body that can be seen by
predators.
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These fish feed on zooplankton (tiny aquatic animals), small fish, and other
small creatures.
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This species can cover their light-emitting organs with a flap of skin, and can
either flash their lights to confuse predators or turn their lights off and change
direction to escape.
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Flashlight fish also use their bioluminescent organs to improve their sight while
searching for food, and the light might even attract their prey towards them.
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Some scientists believe that these lights are also used for communication, and
individuals will blink their lights to communicate with each other.
Image 2: Bioluminescent deep-sea brittle star
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There are over 2,000 species of brittle star, of which over 70 are known to be
bioluminescent.
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Brittle stars use their bioluminescence for defence and can detach their limbs
to distract predators from their main body.
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The light from brittle stars can alert larger animals to the location of a predator
that is trying to attack them, turning the tables and allowing them to escape.
Image 3: Firefly glowing in Germany
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Fireflies have a large distribution and are found in North and South America,
Europe and Asia, where they usually inhabit forested areas with open water,
although some can be found in drier habitats.
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Fireflies use bioluminescence as a method of communication between males
and females during mating season, with females using the quality and
brightness of a male’s light to determine their virility. If the female is receptive
to mating, it will flash its lantern towards the male. Each firefly species has its
own series of flashes which help them to distinguish between their and other
species.
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Female fireflies will often mimic the flashes of other species to entice males.
Once the male is close by, the female eats the male and harvests his toxins as
it cannot produce its own.
Image 4: Glow worm female glowing
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The common name of Lampyris noctiluca, or ‘glow worm’, is misleading as
this species is actually a type of beetle. The female glow worm is wingless and
is able to produce a strong yellow-green light to attract males who fly close
by.
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Rather than producing light in flashes, like fireflies, the female glow worm
produces a constant light that is turned off once it has mated.
Image 5: Deep sea dragonfish with bioluminescent lure, from between 498 and
805m, Mid-Atlantic Ridge, North Atlantic Ocean
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Dragonfish live in the deep sea and have been recorded at depths of over
2,000 metres.
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The long, fleshy appendage that extends from underneath the mouth of
dragonfish has a bioluminescent lure on the tip which is used to attract prey.
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The light-producing organs underneath the eyes of dragonfish are used to
search for prey.
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An extremely clever adaptation allows dragonfish to emit and see red light
and as most deep sea fish can only see blue light, they are able to search an
area for prey without being detected.
Image 6: Big fin reef squid in deep water, showing bioluminescence in Indonesia
Indo-Pacific
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Cephalopods produce an impressive light show using bioluminescence, with
light-producing photophores covering a large majority of its body and
flashing in mesmerising patterns.The light produced by squids serve many
purposes, including preventing predation, communicating with potential
mates and attracting prey.
Image 7: Cardinal fish (Apogon sp) moments after it has mistakenly tried to eat an
ostracod
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When attacked, the ostracod releases glowing mucus that is so bright that it
can be seen through the body of the fish. This gives the fish a shock, and it
spits the ostracod out, which continues to draw attention to the fish by
swimming in tight circles ejecting more glowing material. The ostracod can
be seen at the bottom of the picture making its escape. This all makes the fish
extremely visible to any predators on the reef.
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Flashes of light can be an extremely effective way of deterring predators from
attacking, as not only can it startle an individual and make it confused about
the location of its prey, but it can also alert bigger predators to the location of
the original predator and initiate an attack on them.
Image 8: Bioluminescent fungus gnat larvae on cave roof with sticky silk threads
hanging down, Glowworm Cave, North Island, New Zealand
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This fungus gnat is endemic to New Zealand. The larval stage, which lives in
wet caves or sheltered, humid patches of forest, is luminescent.
Image 9: Bioluminescent fungi glowing on tree trunk in rainforest at night, Australia
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Bioluminescent fungi are found throughout the world, although they are
mostly found in the tropics. There are thought to be at least 70 light-producing
fungi species.
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The light produced by fungi is a constant neon green glow.
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The purpose of foxfire fungi light is unknown, although some scientists believe
it helps the fungus to attract insects, which their spores become attached to.
The insects then spread the spores throughout the forest. However, the
mycelium (main fruiting body) of certain species glows rather than the gills
where spores are found, and the reason for these species’ bioluminescence is
a mystery.
Notes for Exercise 2: Firefly Communication: Pupils will try to communicate with each
other by flashing lights in a particular sequence
Materials: Lights and flashcards
Instructions:
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Divide your class up into 6, 9 or 12 groups.
Give each group one of the three flashcards (there should be at least 2
groups with each type of flashcard).
There will be a pattern of dots and dashes on each card. This is your unique
series of flashes that distinguishes your species from other species of firefly.
Each group’s task is to locate another firefly of the same species by both
flashing its sequence and looking out for another sequence that is the same.
Each group will match with at least one other group (depending on the
number of groups). A ‘dot’ indicates a short flash of around 1 second and a
‘dash’ indicates a long flash of around 3 seconds. This should be
demonstrated to the class.
Turn out the lights, making the room as dark as safely possible, and let each
group practice flashing their sequence. Then give the class a certain amount
of time (around 5 minutes) to try to locate another of their species using only
their flashing lights.
Discuss:
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What were the challenges of trying to communicate using only light?
Why were some successful and others not? (Answers might include:
distance, simpler signal, signal more distinct)
What made it hard to communicate? (Answers might include: hard to
concentrate with so many flashing lights, difficult to determine if the flash
was long or short)
Notes for Exercise 3: Foraging Flashlight Fish
Materials: Lights, prey cards
Instructions:
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Divide your class into 3 groups. The groups do not need to be of equal size,
and there should be the greatest number in Group 2, and the fewest in Group
3.
Group 1 will be the flashlight fish and each pupil in this group
should have a light.
Group 2 will be the flashlight fish’s prey, and each will be given
one of the prey cards. They do not have lights.
Group 3 will be a predator that feeds on the flashlight fish. They
do not have lights.
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Turn out the lights, making the room as dark as safely possible, and give the
class a certain amount of time (around 5 minutes) to act like their animal.
In the dark, Group 1 should turn on their lights to try to find and capture one
of the prey cards (each held by someone in Group 2).
Group 2 will be attracted to the light. They should slowly move towards the
nearest light that they see, holding out their prey card. If they meet someone
in Group 1 they should give them their card and then go and sit down.
Group 3 are the predators that are trying to catch the flashlight fish (Group 1).
If they find someone in Group 1, they should ‘capture’ them, so Group 1 must
be secretive with their lights. The captured flashlight fish should go and sit
down and then the predator should go back to the game to try to catch
another flashlight fish (someone from Group 1).
The individuals in Group 1 need to work out how they can turn on their lights in
order to find their food, but not attract a predator.
At the end of the session, count how many of each group are still in the
game. By restricting game time to just 5 minutes, there should be a mix of
Group 1 and 3 left at the end of the game.
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Discuss:
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How were the flashlight fish able to find their prey items?
How many prey cards do each of the uncaptured flashlight fish hold?
Ask the flashlight fish with the most prey cards what strategy they used.
What other techniques can be used to find food whilst avoiding capture?
(Answers might include: the fish can either flash their lights to confuse
predators, or turn their lights off and change direction to escape).
For more information:
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Arkive - Bioluminescence: http://www.arkive.org/c/bioluminescence