Method and device for plankton separation

A plankton separating device comprising:

• a darkened chamber having an outer perimeter surrounding a vertical central axis, and a maximum outer perimeter dimension that extends downwardly to a darkened narrowed section which ends at a port at the bottom, wherein the darkened narrowed section has an inner opening having a size above 13 mm and up to 21.5 mm ±2 mm and an openable closure;
• and
• a light permeable collection tube extending along the vertical central axis attached to the port for allowing highly directional ambient light to enter the collection tube and pass upwardly through the darkened narrowed section and inner opening which are configured to produce a narrow defined beam of light upwardly into the darkened chamber along the vertical central axis without inhibiting zooplankton migration therethrough when the closure is open, wherein the collection tube is of sufficient length to reinforce migration of the zooplankton downwardly, by extending downwardly away from the darkened chamber beyond a point that makes about a 20°±2° angle to the vertical central axis while extending to a nearest location of maximum outer perimeter dimension of the darkened chamber, thereby providing a contrast shadow from the darkened chamber relative to the collection tube simulating a predator to zooplankton, and a length in the collection tube for zooplankton to migrate from and move away from the darkened chamber a sufficient distance to minimize zooplankton collected in the collection tube from migrating back into the darkened chamber, thereby separating plankton into its component parts,
• wherein the closure is configured to be changed from a closed state to an open state.