Parasitism and Mutualism

Some species live together in symbiotic relationships. There are several types, but two common forms of symbiotic relationships are:

  • Parasitism
  • Mutualism


Parasites live within or on a larger organism, which is called a host. The parasite benefits by taking nutrients from the host, but the host often suffers harm and gets no benefit in return.

An illustrative depiction of parasitism featuring a brown cat on the left and a tick on the right. Above, a label reads "PARASITISM". A green arrow points from the cat to the tick, accompanied by a smiling emoji, indicating the benefit to the tick as "The tick feeds on cat's blood", marked with a green tick symbol. Conversely, a red arrow points from the tick to the cat, paired with a sad emoji, indicating the negative effect on the cat as "The cat gets skin irritation", marked with a red cross symbol. The diagram visualises the one-sided relationship between the cat and the tick.

In humans, an example of a parasite is the tapeworm, which lives inside the gut. It ‘steals’ nutrients from the host, which can lead to malnutrition.


Mutualism is a type of relationship in which both species involved benefit from their interaction, such as through the exchange of nutrients.

An example of this is the mutualistic relationship between flowers and bees. Bees get nectar from the flowers, which they can use for food. In the process, bees spread the flower pollen to other flowers, which helps with plant reproduction.

A visual representation of mutualism, with vibrant purple flowers on the left and a bee beside honeycomb shapes on the right. Above, a label reads "MUTUALISM". Green arrows with smiling emojis point bidirectionally between the bee and the flowers. The benefit to the flower is described as "Flower gets pollinated", marked with a green tick symbol below it. The advantage to the bee is detailed as "Bee gets nectar", marked with a green tick symbol next to it. The image portrays the symbiotic relationship where both organisms benefit.

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