upper water layer

The hydrology of the upper water layers is largely determined by the flow from the North Atlantic.

Top-water fish (fish Plageime) - are usually in groups and find their food upper water layer.

N. trifasciatus rests near the water surface at night and during the day inhabits the middle to upper water layers.

Eastern basin is almost no vertical currents and thus no mixing between the upper water layer and bottom layer of water.

Larvae and immatures inhabit the upper water layers, down to some dozen meters; larvae before notochord flexion/metamorphosis in particular can sometimes be found right at the surface.

While details the braincase bones are held to be very informative phylogenetically, the skull features in which the two groups are similar are generally related to the point where the bill attaches to the skull, and thus might have been subject to the selective forces brought about by skimming food from the upper water layer.