Not all. This fungus is a lichen, providing nutrients to the tree. The lichen gets sugars from the plant. Both benefit from this relationship.
Symbiotic Relationships of Fungi
Not all fungi feed on dead organisms. Many are involved in symbiotic relationships, including parasitism and mutualism.
Fungi as Parasites
In a parasitic relationship, the parasite benefits while the host is harmed. Parasitic fungi live in or on other organisms and get their nutrients from them. Fungi have special structures for penetrating a host. They also produce enzymes that break down the host’s tissues.
Parasitic fungi often cause illness and may eventually kill their host. They are the major cause of disease in agricultural plants. Fungi also parasitize animals, such as the insect pictured in Figure below. Fungi even parasitize humans. Did you ever have athelete’s foot? If so, you were the host of a parasitic fungus.
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