you are ever lucky enough to dive deep into the ocean in a submersible, be sure
to turn out the lights. You will be treated to one of the greatest natural
light shows on the planet—explosions of blue sparks, puffs of liquid-blue
smoke, and dancing electric-blue racing stripes that swirl and stretch into
nothingness. All this light is bioluminescence—visible light made by
living creatures. Rare on land, bioluminescent organisms are common in the
oceans, particularly in the upper 3,000 feet. This is a world without hiding
places, where sunlight filtering down through the depths decreases until all
visible light disappears around that 3,000-foot level. In this twilit realm, the
light is dim and blue and highly directional, so the only animals visible are
either directly overhead or producing their own light. In this slide show, meet
some of the bizarre creatures that create bioluminescence and learn how they
use it to survive in the oceans.
Edie Widder, an expert in bioluminescence, is a biologist and deep-sea explorer.