Biotic Relationships: Commensalism, Niche, Parasitism

Niche

• An organism’s ecological ROLE in the environment (NOT HABITAT!)
• All components of lifestyle and how they affect other organisms

Three Types of Symbiosis

Mutualism

• both species benefit

Commensalism

• one species benefits, the other is unaffected

Parasitism

• one species benefits, the other is harmed

Lichen

• Lichen is really two organisms: algae and fungus. The fungus needs food but cannot make it. The algae makes food but needs some way to keep moist. The fungus forms a crust around the algae which holds in moisture. Both organisms benefit.

Bedbugs

• Bedbugs are small, nocturnal parasites that come out of hiding at night to feed on unsuspecting humans.  They feed exclusively on blood!  Their bites often result in an allergic reaction.

Tapeworms

• The definitive host of the cucumber tapeworm is a dog or a cat (occasionally a human). Fleas and lice are the intermediate host. the dog or cat becomes contaminated when the eggs are passed in the feces, and the flea or louse ingests the eggs.  The dog or cat (or human) is infected when they ingest a flea or louse.  Hence the importance of controlling fleas on your pet!