Fig. 4. The flow generated by crayfish fan organs consists of the jets and the inflow (A). The inflow converges towards the jets' origin and towards jets' axes. At a distance larger than the jets' length the flow is virtually unaffected by a crayfish fanning activity. The jets are generally out of horizontal plane, so the sketch shows a projection. To mimic the flow created by a crayfish, an assembly of an inlet and two outlet nozzles (B) was designed. The water was pumped through a closed loop providing fluid conservation, which is obviously the case for a crayfish.