Symbiosis - Relationship between two organisms (of different species) where they interact with each other for most of their lives. It comes in three flavors (Table 33.1)

• Mutualism - Both organisms benefit
  • bacterium Rhizobium and leguminous plants (soybeans, clover). Rhizobium converts Nitrogen in the air to a form that the plant can use to make amino acids and nucleotides (very important for life!). The plants provide carbohydrates for the bacteria (33.1) See slide.
  • Lichens: a fungus with either an alga or cyanobacterium (we saw this in lab 15). Observe slide. Notice the three forms in figure 33.2.
    • Crustose
    • Foliose
    • Fruticose
  • Ants and Acacias - pretty neat, see figure 33.4
  • Others - fungus mycorrhizae (from lab 15) helps plant roots absorb minerals; Bacteria in our gut produce vitamin K (blood clotting)
• Commensalism - one species benefits, the other in unharmed.
  • Epiphytes - Plants that grow on other plants without hurting them. We have a few in the Smokies. See the orchid in Figure 33.5
  • Many animals use other animals for transportation or live of their leavings (are dogs commensal, symbyotic or maybe parasitic?)
• Parasitism - the parasite derives nourishment from the host, harming but usually not killing.
  • Plasmodium (Malaria) Life cycle on Figure 33.6 How is malaria controlled? Observe slide.
  • Tapeworms - We've seen this guy before(lab 22). Observe slide. How does this parasite differ from free-living flatworms like planaria? Planaria needs to search for food so it has a head, brain, sense organs, digestive system, muscles, etc.

Food Web

Food Chain - Linear sequence of steps by which energy stored in autotroph tissues enters higher trophic (food) levels

Food Web - Cross-connecting food chains.

A food web is about energy flow. Energy is captured from the sun by the Producers (autotrophs) which are then eaten by the various Consumers (heterotrophs). Usable energy is lost at each stage and is released as heat (as the second law of thermodynamics requires)

• Producers (autotrophs) ->
• Primary Consumer (herbivores) ->
• Secondary Consumer (carnivores) ->
• Tertiary Consumers eat the secondary consumers.
• Omnivores (like us) can be at any level of consumer
• Detritus Feeders - Detritus is the particulate remains of dead plants and animals. Most of the dead plant material (leaves and wood for land plants) are consumed by detritus feeders such as earthworms and termites. Scavengers such as crows and vultures as well as maggots can be considered detritus feeders.
• Decomposers (fungi and bacteria) are the final step in energy extraction and recycle nutrients back to the Producers.

Energy Flow
Food Web Example 1	Food Web Example 1