The Language of Light in the Deep Sea

Have you ever wondered how animals communicate, find food, mates and defend themselves in complete darkness?  The answer is that most deep-sea animals have evolved the ability to produce their own light, and this is called bioluminescence.  Most deep-sea creatures either have all the machinery to produce bioluminescence themselves (examples include fish and crustaceans), while others form a unique relationship with glowing bacteria that live in their light organs (example include squid and angler fish).  This results in a beautiful underwater display of flashes, sparks and glows, much like a fireworks display on the 4^th of July.  However, in the deep-sea, where food and mates are limited and predators lurk in complete darkness, this light show is not for fun.  The stakes are high, and this underwater “language of light” is critical for the animal’s survival.  

During this cruise we have witnessed some incredible examples of bioluminescence which I am excited to share with all of you. 

Deep-sea flashlights:  Do you see all those beautiful dots of purple and red?  Those are called photophores, or light organs, which glow in the dark.  Much like a flashlight they can turn on and off when needed and can be tuned to match the brightness around them.  In many cases they are found along the entire surface of the animal’s body and can be used to lure in prey (oh, something shiny!!), defend themselves (ahhhh, too bright!!) or communicate with others of the same species (hey, you see me over here, what is yourrrrr name?).  Below, you are looking at a loosejaw fangfish (Aristostomias) and Viperfish (Chauliodus sloani).  One has a bring red light organ below the eye and the other has light organs all over!  

Photos:  H. BRacken-Grissom

Glowing blue vomit:  Did you know the deep-sea shrimp can vomit a bright blue glowing mucus?  Yep, it is true, and they do this to protect themselves when they get scared.   Ingenious, huh?  Below, you are looking at a deep-sea shrimp by the name of Notostomus gibbosus.  When startled, this deep-sea beauty will secrete a blue smokescreen that will stun a predator while they tail-flip backwards to escape.   Gooo team shrimp!

Photo: H. Bracken-Grissom

Wonder what it looks like?  See below....

Photo:  Sonke Johnsen

The Language of Light:  We know very little about how dee-sea creatures use bioluminescence to communicate due to the difficulties of studying these creatures in their natural habitat.  However, it is possible that these beautiful multi-colored barbels could be the clue.  Do these help find mates?  Do they lure in prey?  Both?  I assure you we are going to have some fun exploring and trying to solve the many mysteries that the deep-sea holds.  Until next time……. 

Photo:  H. Bracken-Grissom