Symbiosis: living closely together

Science · Animals of the World · ages 9-11

Name ______________________ Date ____________

A bee drinks nectar from a flower. As it feeds, pollen sticks to its body and helps the flower make seeds. How many of the two species benefit?
Answer: ______________
Which of these is an example of symbiosis?
- A bee visits a flower for nectar and carries its pollen away
- Two squirrels from the same family share one nest
- A fish swims alone across the whole pond
What is the name for a relationship where one species benefits and the other is not helped or harmed?
- Parasitism
- Mutualism
- Commensalism
Clownfish live safely in an anemone's tentacles and clean it in return. What type of symbiosis is this?
- Mutualism
- Parasitism
- Commensalism
Which of these relationships is commensalism?
- A bird builds a nest in a tree, and the tree is not affected
- A bee drinks nectar from a flower and pollinates it
- A tick feeds on a deer's blood and weakens it
Ants live inside a thorny acacia tree and attack insects that try to eat its leaves. The tree gives the ants food and a safe home. What type of symbiosis is this?
- Parasitism
- Commensalism
- Mutualism
A tick attaches to a deer's skin and feeds on its blood, weakening the deer over time. What type of symbiosis is this?
- Mutualism
- Commensalism
- Parasitism
In commensalism, one species benefits and the other is harmed a little bit.
Circle one: True False
Tom says a tick living on a deer is mutualism because the two animals live so closely together. What is wrong with his idea?
- Living closely is not enough; the deer is harmed, so it is parasitism
- He is wrong because ticks and deer are the same species
- Nothing is wrong; close partners always help each other
Zara says the clownfish and the sea anemone show commensalism, because the clownfish is the one doing all the cleaning work. Is she right?
- No, it is parasitism because the anemone is harmed
- No, it is mutualism because the anemone benefits too
- Yes, because only the clownfish does something helpful

Answer key

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Symbiosis: living closely together W1-mt_H8OgKZbgGe-s1

2 · The bee gets food and the flower gets help making seeds, so both of the 2 species benefit.
A bee visits a flower for nectar and carries its pollen away · Symbiosis needs two different species living closely together. A bee and a flower are different species, and each one affects the other's life.
Commensalism · One species gaining something while the other is unaffected is called commensalism, like the remora riding a shark.
Mutualism · The clownfish gets protection, and the anemone gets cleaned and defended. Since both gain, it's mutualism.
A bird builds a nest in a tree, and the tree is not affected · Only the nesting bird gains while the tree is unaffected, which is commensalism. The bee and flower both gain, and the tick harms the deer.
Mutualism · The ants get food and shelter, and the tree gets protection from leaf eaters. Both sides gain, so it is mutualism.
Parasitism · The tick gains a blood meal, but the deer is harmed by losing blood. One side benefits at the other's expense, so it's parasitism.
False · Commensalism means one species benefits and the other is not harmed at all. If harm happens, the relationship is parasitism.
Living closely is not enough; the deer is harmed, so it is parasitism · All symbiosis is close living, but the type depends on who benefits and who is harmed. The deer is harmed, so this is parasitism.
No, it is mutualism because the anemone benefits too · Doing the work does not decide the type. The anemone gets cleaned and protected, so both benefit and the relationship is mutualism.