 He also studied the vision of shrimps in hydrothermal vents, and how the oxygen minimum in the northwestern Indian Ocean affected the distribution of midwater animals.He served as chief scientist on at least sixty research voyages.In 1981 he discovered red bioluminescent "searchlights" below the eyes of some dragonfish, and showed that these worked by using fluorescent proteins which shifted the mainly blue light actually generated by these fish into the red part of the visible spectrum.