The influence of parasites commonly results in the targeted natural behavior change of infected intermediate hosts, which contributes to the transition of a pathogen to a final host. At the same time the behavior manipulation mechanisms that are species-specific and common to various parasites provide the aberrations in the behavior of invertebrates and fishes under the influence of phylogenetically different parasites, which promote survival and completion of their life cycles. The influence of parasites on the metabolism of the neurotransmitter serotonin in the intermediate hosts is of considerable importance in altering the phototaxis of invertebrates and fishes.
