Answer:
Parasitism
ExplanatioThe flatworm seems to be the only one benefitting from the relationship because it is using the snail as a host and provides it a place to grow but the snail is being harmed by the worm while doing so. Therefore the relationship is parasitic.
Answer:
a scientific theory of the origin of species of plants and animals
Answer:
A and D I think
Explanation:
It's not erosion, so that is out of the answer choices. And I doubt it is crystallization, so that is why I think it is A and D. (correct me if I am wrong.)
It is useful for an ecologist to identify the keystone species in an ecosystem because the keystone species is important to maintaining the stability of an ecosystem, and any changes in the keystone species population shows that there is changes in ecosystem health.
