Mixed light imaging system for recording bioluminescence behaviours

Video recordings of bioluminescence have depended on the use of image-intensified systems, which generally suffer from poor resolution and image persistence. These characteristics, coupled with the restriction that any illumination must be dimmer than the bioluminescence, have complicated efforts to record behaviours associated with bioluminescent displays. The Mixed Light Imaging System (Mlis), described here, uses (1) an intensified video camera, (2) an infra-red (IR) sensitive video camera (3) a dichroic beam splitter, (4) strobed IR illumination and (5) a video mixer to record stop-action images of organisms superimposed on intensified images of their bioluminescence. With the MLIS, behaviours associated with bioluminescent emissions, including rapid escape responses, were recorded from the mesopelagic copepods Euaugaptilus magnus and Gaussia princeps.