Symbiosis is a close relationship between two organisms. There are three types of symbiosis: mutualism, commensalism and parasitism. Mutualism is a relationship where both organisms benefit. Commensalism is a reltionship where one organism benefits and the other is not harmed. Parasitism is a relationship where one organism benefits and the other is harmed. Mutalism may occur between a dog and human. Both of them help each other; where the human gives love and support to the human, the human gives the dog shelter and care. Both are benefiting from the realtionship, therefore it is a mutual relationship. An example of commensalism would be moss and a tree. The moss has a home and food, as for the tree is just helping out without anything in return. Hence, moss benefits and the tree is unharmed. A worm inside a bird is an example of prasitism. The worm will reproduce and get food from nliving inside the bird as the bird is infected and will soon die. In this case, the worm benefits and the bird is harmed. This is what we learned in science about symbiosis.
