Final answer:
Symbiotic relationships include mutualism, commensalism, and parasitism. Mutualism benefits both species, commensalism benefits one species while the other is not affected, and parasitism benefits one species at the expense of the other.
Step-by-step explanation:
Symbiosis is a close relationship between two species in which at least one species benefits. There are three types of symbiotic relationships: mutualism, commensalism, and parasitism.
In mutualism, both species benefit from the relationship. An example of mutualism is the relationship between bees and flowers, where the bees pollinate the flowers and in return, the flowers provide nectar and pollen as food for the bees.
In commensalism, one species benefits while the other is not affected. An example is the relationship between a barnacle and a whale, where the barnacle attaches to the whale's skin and gains protection and access to food, while the whale is unaffected.
In parasitism, one species (the parasite) benefits at the expense of the other species (the host). An example is the relationship between a tick and a dog, where the tick feeds on the dog's blood and harms the dog in the process.