| In order to understand the structure of pineal window, and relationship of pineal window and life habit, fish phylogenetic of Scombridae fishes, histological structure of pineal window in yellowfin tuna (Thunnus albacares) and chub mackerel (Scomber japonicus) were investigated by using anatomy, X-ray and histology methods. Besides, the relation of pineal window, fish phylogenetic relationship and the possible physiological function of pineal window were investigated among fish samples randomly collected from 9 orders and 17 families in 20 species. The results showed that fishes with pineal window normally lived in offshore or benthonic environment, and the existence of pineal window had connection with their living environment. When fishes lived in low light environment,this special structure could let more sun light reach brain and regulate physiological function in fish. In the meantime, migrating species
of ocean fish had pineal window, a function of determining migratory route according to perception of light was also inferred. |
