Ocean twilight zone scientists tackle the challenge of bringing light into darkness
(PHYSorg.com Biology)

Oceanographers studying creatures in the ocean twilight zone are facing an optical dilemma. They need to observe the fish in order to study them, but at ocean depths of 200 meters and beyond, there`s very little natural light trickling down from the surface. This means that submersibles developed to image and track these animals need to be equipped with lights that can illuminate the animals-and do so without scaring them off.