Video Setup
All experiments were conducted in a darkroom and recorded under infrared illumination.
Two types of video systems were employed, one for each type of experiment,
which allowed for real-time monitoring of fish behavior and dinoflagellate
bioluminescence.
In the video setup used to record capture success experiments, the experimental
tank was illuminated from behind using a slide projector (500 W incandescent bulb)
with 2 Kodak IR filters (Wratten No. 89B) and a neutral density filter (Tiffen 0.6). The
light was projected onto a mirror situated at a diagonal behind the tank and further
diffused through white Plexiglas. The events of the trials were monitored with an
intensified camera (I2CCD) (Intevac GenIII Nitemate 1305/1306 with a CCTV intensifier)
(Fig. 1).
In the video setup used to record distance experiments, the experimental tank was
illuminated from behind using a 7.5 W incandescent light source filtered through
two Kodak IR filters (Wratten 89B) and diffused through white Plexiglas. A mirror
(14.6 × 22.2 cm) was situated at a 45° angle from the top rear rim of the tank to
give a three-dimensional view of the position of the fish relative to the shrimp. The
tank and mirror were also illuminated from below using a slide projector with a 500
W incandescent bulb filtered through a Kodak IR filter (Wratten 89B) and white
Plexiglas. The video system in these trials was based on the design of Widder (1992).
Briefly, an intensified camera (Dage-MTI ISIT 66) that recorded bioluminescence
was synced to an infrared sensitive camera (Dage-MTI SC-68 with an IR Ultricon tube) that simultaneously recorded the actions of the organisms in the chamber and
the two signals fed through a video mixer (Primebridge MicroSeries PVM-1) (Fig. 2).
For both video setups, the events of the experiments were projected onto a Panasonic
monitor outside the darkroom while simultaneously recorded on a Sony Hi-8 video
recorder for later viewing.