In this video, we're going to begin our lesson on symbiotic relationships. Of course, we know that different organisms can survive in the same environment, which means that different living organisms, for example, humans and microorganisms, are going to interact with each other to form what we refer to as symbiotic relationships. The term symbiosis refers to the specific biological interactions or relationships between two different organisms or species.
There are three forms of symbiotic relationships that we have numbered below: 1, 2, and 3. The three forms of symbiotic relationships are mutualism, commensalism, and parasitism. Now, mutualism is a relationship between two organisms where both organisms benefit from the relationship. Commensalism is a relationship between two organisms where one organism benefits from the relationship, but the other organism is unaffected, meaning that they neither benefit nor are harmed by the relationship. The third type of symbiotic relationship is parasitism. In parasitism, it describes a relationship between two organisms where one organism benefits at the expense of the other, meaning that the other organism is harmed by the relationship. All pathogens or disease-causing agents are categorized as parasites.
If we look at our image, which is a table that helps us better understand the three types of symbiotic relationships, we have three columns: the interaction between two organisms, the relationship type, and a biological example of the relationship. When there is an interaction where both organisms benefit, we refer to this as a mutualistic relationship or just mutualism. For example, flowers have a mutualistic relationship with honeybees because the flowers get pollinated by the activity of the honeybees, and the bees collect nectar for making honey from the flowers. Both organisms benefit from this relationship, so we call this mutualism.
If there is an interaction between two organisms where only one organism benefits and the other is unaffected, we refer to this as commensalism. In commensalism, species A will benefit, but species B is unaffected, meaning they neither benefit nor are harmed. An example of this relationship is between barnacles and whales, where barnacles stick to whales for transportation, benefiting the barnacles, but the whales are neither harmed nor significantly benefit from the barnacles, so they remain unaffected, making this relationship commensalism.
If there is a relationship between two organisms where one benefits but the other is harmed, we refer to this as parasitism. In parasitism, species A benefits at the expense of species B who is harmed. For example, ticks and dogs have a parasitic relationship because the tick feeds on the dog's blood, benefiting by getting nutrients, but the dog is harmed by losing blood and potentially getting infections. The tick benefits at the expense of the dog, which is harmed.
This concludes our brief lesson on symbiotic relationships and the three types of symbiotic relationships: mutualism, commensalism, and parasitism. We'll be able to get some practice applying these concepts as we move forward in our course. I'll see you all in our next video.