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Symbiosis worksheet: mutualism, commensalism and parasitism (with answer key)
Symbiosis worksheet: a 12-pair table, short questions on mutualism, commensalism and parasitism, reflection prompts and an answer key.
This worksheet is ready to print: use your browser’s print command (Ctrl+P or ⌘P). The answer key for teachers is at the end and starts on a new sheet when printed. The full lesson is on the lesson page. Symbiosis: mutualism, commensalism and parasitism (Grade 7)
Phase D · Lower secondary grade 7 · IPA
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Learning goals
- Students can explain what symbiosis is and its three types.
- Students can classify pairs of organisms as mutualism, commensalism or parasitism using gain and harm.
- Students can give examples of symbiosis involving Indonesian animals.
- Students can tell symbiosis apart from predation and competition.
Short reading
Symbiosis is a close, long-lasting relationship between two different kinds of living things. In mutualism both gain (clownfish and anemone), in commensalism one gains and the other is unaffected (orchid and tree), and in parasitism one gains and the other is harmed (cat flea and cat). It is taught in Indonesia's Grade 7 science book, Chapter VI.
- Symbiosis has three main types: mutualism (+/+), commensalism (+/0) and parasitism (+/−).
- Clownfish and sea anemones are mutualists: the anemone protects the fish, and the fish drives off the anemone's predators.
- Epiphytic orchids are not parasites; they grow on trees without taking nutrients from them, so they are commensals.
- Only female Aedes mosquitoes feed on blood, to produce eggs; their relationship with people is usually classed as parasitism, though ecologists call mosquitoes micropredators.
- Cattle egrets mainly eat insects disturbed by buffalo, so the pair is usually classed as commensalism; if the egret eats ticks off the buffalo's hide, it becomes mutualism.
- Symbiosis is different from predation and competition, which are also interactions between living things.
Activity 1
Decide the type of symbiosis for each pair (mutualism, commensalism or parasitism) and give your reason using +, 0 or −.
| No | Pair of organisms | Type of symbiosis and reason |
|---|---|---|
| 1 | Clownfish and sea anemone | |
| 2 | Asian honey bee and flowers | |
| 3 | Large flying fox and durian tree | |
| 4 | Knobbed hornbill and forest fruit trees | |
| 5 | Giant clam and zooxanthellae | |
| 6 | Orchid and mango tree | |
| 7 | Remora and shark | |
| 8 | Cattle egret and water buffalo | |
| 9 | Cat flea and cat | |
| 10 | Brown dog tick and dog | |
| 11 | Female Aedes mosquito and people | |
| 12 | Mistletoe and tree |
Activity 2
- Explain the difference between mutualism, commensalism and parasitism in your own words.
- Why is an orchid growing on a tree not a parasite?
- What does the clownfish get, and what does the sea anemone get, from their relationship?
- Your friend says, "Buffalo and mynas are definitely mutualists." How would you respond?
- How is predation different from parasitism?
Reflection
Which example of symbiosis can you find near your home or school?
Which type of symbiosis is hardest for you to tell apart? Why?
Why is it important to check whether an example in a book or online is backed by research?
Answer key (for teachers)
Activity 1
- Clownfish and sea anemone: Mutualism (+/+): the fish is protected, the anemone is guarded from predators
- Asian honey bee and flowers: Mutualism (+/+): the bee gets nectar and pollen, the flower is pollinated
- Large flying fox and durian tree: Mutualism (+/+): the bat gets food, the tree is pollinated and its seeds spread
- Knobbed hornbill and forest fruit trees: Mutualism (+/+): the bird gets fruit, the seeds are spread
- Giant clam and zooxanthellae: Mutualism (+/+): the clam gets food, the algae get a home
- Orchid and mango tree: Commensalism (+/0): the orchid gets a place to grow, the tree loses no nutrients
- Remora and shark: Commensalism (+/0); can be close to mutualism because remoras also eat the shark's parasites
- Cattle egret and water buffalo: Commensalism (+/0): the egret gets disturbed insects, the buffalo is unaffected (mutualism if the egret eats the buffalo's ticks)
- Cat flea and cat: Parasitism (+/−): the flea gets blood, the cat is harmed
- Brown dog tick and dog: Parasitism (+/−): the tick gets blood, the dog can become ill
- Female Aedes mosquito and people: Usually classed as parasitism (+/−): the mosquito gets blood for eggs, people can catch diseases; ecologists also call mosquitoes micropredators
- Mistletoe and tree: Parasitism (+/−): the mistletoe gains, the tree is harmed
Activity 2
- Explain the difference between mutualism, commensalism and parasitism in your own words. Mutualism: both gain. Commensalism: one gains, the other is unaffected. Parasitism: one gains, the other is harmed.
- Why is an orchid growing on a tree not a parasite? Epiphytic orchids take no nutrients directly from the tree; they only grow on it.
- What does the clownfish get, and what does the sea anemone get, from their relationship? The clownfish is protected by the anemone's stinging tentacles. The anemone is guarded from its predators by the clownfish.
- Your friend says, "Buffalo and mynas are definitely mutualists." How would you respond? It is only true if the birds are shown to reduce the buffalo's parasites. The documented example, the cattle egret, mainly eats insects disturbed by the buffalo, so it is usually classed as commensalism; it becomes mutualism only if the egret eats ticks off the buffalo's hide.
- How is predation different from parasitism? In predation a predator hunts and eats its prey. In parasitism a parasite lives with its host for a long time and benefits at the host's expense.
Sources: Keputusan Kepala BSKAP Kemendikdasmen No. 046/H/KR/2025 tentang Capaian Pembelajaran, CP IPA Fase D ↗ · Kemendikbudristek — IPA Kelas VII, Edisi Revisi 2023, hlm. 172 ↗ · Anemonefish use sialic acid metabolism as Trojan horse to avoid giant sea anemone stinging (BMC Biology 2025, PMC) ↗ · Animal Diversity Web: Ctenocephalides felis (pinjal kucing) ↗ · University of Georgia Extension (Forsyth County): Amazing facts about orchids ↗ · Insects (2022), Genetic Structure of Apis cerana Populations from South Korea, Vietnam and the Russian Far East (PMC) ↗ · Insects (2024), Decline in Honeybees and Its Consequences for Beekeepers and Crop Pollination in Western Nepal (PMC) ↗ · BBKSDA Sulawesi Selatan (KSDAE, Kementerian Kehutanan): Sulawesi Hornbill (Rhyticeros cassidix) ↗ · FishBase: Amphiprion ocellaris (clown anemonefish) ↗ · Animal Diversity Web: Pteropus vampyrus (kalong besar) ↗ · NOAA National Ocean Service, Corals tutorial: What is zooxanthellae? ↗ · Animal Diversity Web: Tridacna gigas (kima raksasa) ↗
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