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Symbiotic Relationships for one of the organisms to survive

and Fungi without the other.

Every organism interacts with We said earlier that in symbiosis

other organisms every day. These one of the organisms benefits, but
interactions can be helpful, what about the other one? Does it
harmful, or have no effect at all. benefit too? The answer to this
Think about some of the very important question helps
interactions you have had with determine what type of symbiosis
other organisms. If you’ve ever it is. In parasitism, the other
been sick with strep throat, you organism is harmed. In
and some bacteria had a harmful commensalism, the other
interaction. If you pet a dog while organism is unaffected, and in
you were walking down the street, mutualism the other organism
you had an interaction that benefits as well. Look at the
probably had no effect at all. If examples below for some examples

you sat in the shade under a tree of the types of symbiosis.
when you were hot you had an
interaction that was helpful to you.

Many fungi have relationships that
are helpful to them. These

relationships, and any relationship
in which at least one organism
benefits, are called symbiotic
relationships. A true symbiotic
relationship however, is very
different that the relationship
between you and the tree in the
example above. First, your
interaction with the tree was very

brief. Second, although it’s always Figure 6 – These fungi have a parasitic
nice to relax under a tree, you relationship with the horse whose leg is
pictured, causing a severe infection
didn’t actually need to sit under it.
In a true symbiotic relationship,
the two organisms spend their
entire lives together, and it is often
very difficult, or even impossible,

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