Topic OutlineI. Symbiotic Relationship A. Symbiosis 1. Mutualism a. Both Organisms benefit with food or protection. b. In some situations, two organisms are so interdependent with each other that one cannot survive without the other. Like the lichen, which is really a combination of 2 organisms living together – a green algae and a fungus. The fungus protects the algae from bright sunlight and extreme temperatures. The algae provide the fungus with nutrients. 2. Commensalism a. One organism benefits and the other is unaffected. b. Commensal is the one benefited. c. Host is the unaffected. d. Sea anemones use stinging tentacles to catch and stun small fishes and other prey. The clown fish takes shelter in the sea anemone’s tentacles, sharing the sea anemone’s food but giving nothing in return. 3. Parasitism a. One organism benefits, while the other is harmed. b. Parasites live inside (endoparasite) or outside (ectoparasite) the organism. c. Host is the organism that is harmed by the relationship. d. Endoparasites include parasitic worms such as tapeworms, hookworms. B. Predation a. Feeding of one organism on another. b. Prey is the organism eaten by a predator. c. Because predators are more likely to capture old, ill, or extremely young prey, predation helps to maintain the health of a population by leaving only the strongest individuals to reproduce. C. Competition a. It is when two species use the same limited resources. b. Competition can limit how species use resources. c. Often results in elimination of one organism by another.