Aphids eat sap from plants

Aphids are soft-bodied insects that use their piercing sucking mouth parts to feed on plant sap. They usually occur in colonies on the undersides of tender terminal growth. Heavily-infested leaves can wilt or turn yellow because of excessive sap removal.

A parasite organism feeds on and often even lives on a host organism

One benefits and one is harmed 

The shrimp digs a burrow into the sand and both organisms live there. Because the shrimp is almost blind, the goby fish will touch the shrimp when a predator is near.  

Organisms live together and benefit from the help of each other 

Both Organisms benefit 

since both species feed on similar prey, they are negatively impacted by the presence of the other because they will have less food, however they still persist together, despite the prediction that under competition one will displace the other.

Two or more species use the same limited resources

One might benefit, but often neither does

the Canada lynx lies in wait for its favorite prey, the snowshoe hare. Positioning itself along one of the well-beaten trails connecting the hare’s feeding and nesting sites, the lynx sits patiently, its mottled gray coat camouflaging it in the brush. And whether for the thrill of the chase, the tantalizing taste of the hare, or a combination thereof, the lynx will wait hours on end for this moment, the opportunity to pounce on an unsuspecting snowshoe hare.

One predator captures, kills and consumes the prey 

One benefits and one dies

These puffins use burrows for nesting that were made by rabbits.

One organism benefits from the help of another, but the second organism is not harmed nor does it benefit

One benefits, the other does not benefit, but its not harmed