Answer the following questions to the best of your ability

Question

The louse Cymothoa exigua lives inside the mouth of certain fish. It attaches to the fish’s tongue, strangling it until it falls out. Once the tongue falls out, the louse functionally replaces it. Generally, this is thought of as a parasitic relationship.  

What criteria would need to be met for this relationship to be considered parasitic? Is it possible that this relationship could be an example of mutualism or commensalism? Use what you have learned to classify this relationship and explain your reasoning.

Answer 1

This is definitely a parasitic relationship. The reasoning is very clear cut -one organism benefits (the louse) while the other is affected to its detriment (the fish)

Answer 2

This is an example of a parasitic relationship, as the Cymothoa exigua louse benefits from the fish by consuming its blood, and the fish doesn't gain anything, but loses its tongue. An example of commensalism is an orchid attaching to a tree, the orchid receives benefits from the tree, and the tree is not harmed in the process. A mutualistic symbiosis would be the Zooxanthelle that live within coral, they both benefit from each other, therefore it is a mutualistic symbiosis. Parasites generally harm their host, while it's true that the fish is able to regrow its tongue, this takes energy and resources, and since the fish does not benefit in any way from the Cymothoa exigua, this makes it parasitic relationship.