1. How organisms interact with each other
SYMBIOSIS!
How organisms interact with each other

2. What is symbiosis?
Interactions between two organisms where at least one benefits from the relationship
In complex communities (rainforests, coral reefs) it’s usually the rule, not the exception!
Usually involves supply of:
food
protection
cleaning
transportation

3. Notation: We usually show the relationships by using:
+ :Organism benefits (positive interaction) 
- : Organism loses (negative interaction) 
0 : Neutral or no particular effect

4. COMMENSALISM (+/0)
Association between 2 or more species, where one species’ success is increased (i.e. one species benefits)
The other species 'success' is not affected (i.e. does not benefit or lose)
… it’s sure nice that he doesn’t care, since it works out great for me!

5. Example 1:Algae on Turtle’s shell
Turtle supplies substrate (surface and food source) for the algae that grows on it and there is no effect on the turtle

6. Example 2: Epiphytes in tree
Epiphytes grow on the tree trunks so that they have greater access to light, but the presence of the epiphytes has no effect on the tree

7. Example 3: Remora and Shark
Remoras benefit from riding on sharks without doing the sharks any harm. Sharks are very sloppy eaters. Also, while the shark is preoccupied with the main course, the remora slips off, gobbles some scraps, and then reattaches until the next meal.

8. MUTUALISM (+/+)
Association between 2 or more species, where both species are more successful as a result
There is a clear benefit to both organisms in the relationship

9. Example 1: Caterpillars, Ants and Acacias
The caterpillars have nectar organs which the ants drink from, and the acacia tolerates the feeding caterpillars. The ants appear to provide some protection for both plant and caterpillar.

10. Example 2: Sea anemone and clown fish
Sea anemones provide an enemy-free space for fish from its predators. The clown fish may pay for this protection by bringing food to the anemone.

11. Example 3: “Dentist” Fish?
A tiny shrimp fearlessly enters the mouth of a fish for a snack by cleaning its teeth. Fish value this service as the shrimp removes and eats harmful parasites.

12. PARASITISM (+/-)
One species benefits, one species is harmed (i.e. positive/negative relationship)
'Good' parasites do not kill host (which is ultimately bad for the parasite (no more home!)
Note: This is not the same as predator/prey…

13. Example 1: Tick and Deer
The adult female tick attaches itself to an animal host for a blood meal. Tick bites themselves can be painful and irritating. More importantly, ticks can carry a number of diseases that affect humans.

14. Example 2: Leeches… and anything with blood!
Leeches attach to a host, and suck through a tubule that they insert into the organism (rather than making a cut)

15. Example 3: Tapeworms
Tapeworms attach to the insides of the digestive tract of animals and take all the nutrients from their food, and reproduce inside them – when animals defecates – they spread all the little offspring around!