Invasive species are non-native species brought to an ecosystem on purpose or by accident by humans. They out compete the local species for food and other resources and cause damage to the ecosystem. For a species to become invasive they typically reproduce quickly, have a broad diet and do not have a natural predator in the area.
Symbiotic Relationships are when two organisms from different species live IN, ON or NEAR one another and one of these organisms benefits.
Mutualism: BOTH organisms benefit
Commensalism: ONE organism benefits and the other is not affected
Parasitism: ONE organism benefits and the other is HARMED