In Your Nest, Eating Your Food
Some parasites, rather than taking the host's nutrients, will steal their effort and work instead. In particular, a number of species have devised methods for getting others to provide parental care for their offspring.
Sucking You Dry
Larger parasites can't always survive inside the body of the host, so they must remain on the outside. Sometimes, what they extract from their host, like blood, also influences this.
They’re Inside You
Natural selection feedback loops can occur when both organisms benefit in a symbiotic relationship, but they also exist when one species harms another. Thus, parasitic relationships are numerous and varied, including those the exist entirely within the host's body.
Flocking Together
Sometimes a symbiotic relationship can be as simple as one species following around another for an easy meal. The behavior of one can stir up the prey of another, allowing them to eat without as much effort.
Getting Attached
Space can be at a premium in the natural world, so many species have increased the potential area they can live by doing so on top of other, larger species.
Dig a Little Deeper
What is a keystone? It is the stone placed at the center of an arch, the final one in the building process because it allows the structure to bear weight. In nature, a species can be a keystone because of its numerous symbiotic relationships.
Along for the Ride
Commensalism is more difficult to understand because the relationship isn't positive or negative for one of the participants. You could say that the neutral species is 'just along for the ride'. Although with this first example, a ride is exactly what the other species is after.
The Birds and the Bees
Symbiotic relationships can have incredible evolutionary power. Flowering plants make up the vast majority of modern plant species diversity, and a large reason for this is their symbiotic reproductive strategy.
Size and Smarts Aren’t Everything
Who can truly lay claim to the title of 'Humanity's Best Friend'? While we have given that name to the domestic dog, there are other symbiotic relationships that are even more important for the survival and development of the human species.