Lecture #2 Symbiosis Unit 8: Community Interactions

Symbiosis- An ecological interaction in which two or more species live together in a close,long-term association. These types of relationships may help, harm or have no affect on the species involved in them.

Symbiotic Relationships 3 Types 1.Parasitism 2. Mutualism 3. Commensalism

Symbiotic Relationships 1.Parasitism See last note sheet 

2. Mutualism- a symbiotic association in which both partners benefit Example #1- Clown fish use the stinging tentacles of the anemone as shelter from would- be predators. The anemone benefits as the clown fish chase off Butterfly fish, which eat anemone’s. Clownfish waste may also serve as nutrients for the anemones.

Example #2: Ants & Aphids Aphids- small insects that use their piercing mouthparts to suck fluids from the sugar conducting vessels of plants They extract a certain amount of the sugar from this fluid, and the rest of it (‘honeydew’) passes through their body and is released as waste.

Ants take advantage of this fact and ‘milk’ the aphids for honeydew, which they use as food. The ants in return, protect the aphids from insect predators.

Example #3- Nile Crocodile & Egyptian Plover The Nile Crocodile gets parasites and food debris removed by the bird. The Egyptian Plover gets a meal!

3.Commensalism - A symbiotic relationship in which one species benefits and the other is neither helped nor harmed. Much more rare in nature than mutualism and parasitism.

Example #1- Water Buffalo & Cattle Egrets Water Buffalo stir up insects as they graze. Egrets follow them to feed on the insects that are stirred up. The Water Buffalo is neither helped nor harmed in this interaction.

Example #2 Sharks & Remoras Remoras hitch a ride with sharks and dart around, eating scraps floating in the water when a shark feeds. Sharks are not affected by this behavior at all.

Example # 3 Orchids growing on a tree Orchids depend on the tree for mechanical support, but not nutrients. The tree is not helped nor harmed.

Take 2 minutes to summarize the various impacts symbiotic relationships may have on each member of the partnership.