Third Person omniscient means that the narrator can not only hear the protagonists thoughts but also everyone else. Therefore the story can be told from may different perspectives. Hope it helped :)
This detail exemplifies the larger theme of the futility of human efforts to dominate nature.
The entire novel revolves around that theme - whether Ahab as a human is capable of dominating Moby Dic, which is a whale and thus a representative of nature. Nature seems to be winning constantly and humans are ultimately unable to conquer it because nature is unconquerable. <span />
One species(the parasite) benefits while the other species (the host) is harmed
