Diel vertical migration
The vertical migration is in the hydrology, limnology and oceanography, the migration of aquatic creatures on the vertical profile of a body of water - as a specific special form of migration of single individuals and populations that water occur in three-dimensional habitat.
Light Dependent ( phototrophic ) microorganisms (algae, Planktone ) and rotifers, Ruderfußkrebschen and some mosquito larvae migrate through the diurnal thermal layers of the water body, from the lowest, coldest layer to the top, warm layer and vice versa. Since there is no thermal stratification in winter and spring due to the seasonal temperature compensation, this behavior is observed only in the summer. The alga Volvox can cover a height difference of up to 18 m.
The shape of the hike varies depending on the species How can this only on the top, heated and strongly moving layer ( epilimnion ) of standing water or the bottom, few moving layer ( hypolimnion ) restrict - or else from the epilimnion after the hypolimnion. The main reason for the migration is in the course of the day change in the intensity of the incident sunlight.
Some fish, such as lantern fish, make the whole year a vertical migration in the diurnal cycle. Furthermore, it is known in addition to those already mentioned also by larvae of mosquitoes and tufts of Daphnia this behavior.