Migratory organisms, which inhabit much vertical space and are found in many layers throughout 24 h, undertake every day; they feed only at night, in the upper layers which contain much food the daytime, the migratory animals inhabit layers to a depth of 50 m and do not feed at all. This strict feeding rhythm, with the maximum rate occurring in the middle of the night, was found in all typical migrants. It is characteristic of all bathyplankton migratory species.