A glowing firefly squid
(By Nhobgood (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons)
From the thousands of sea creatures that live on great depths, where the sun never shines, this is their light. The Firefly Squid is a really small squid that is also called (3 inch) the Sparkling Enope Squid. Its scientific name is Watasenia Scintillans. It belongs to the class of the Cephalopoda and the order of the Teuthida. It's not hard to guess from where it gets its name, but for the people who don't know it, the firefly squid gives light, just as a normal firefly does and that's why its called the firefly squid.
The habitat of the firefly squid limits itself to the Western Pacific ocean. The firefly squid is a middle-deep sea squid that can live on depths of 600 to 1200 (365m) feet. The body of these little squids are covered with photophores that give a blue light. The main goal of these photophores is to lure little fishes, so that it can catch them easier. Just as the vampire squid, the firefly squid has its photophores totally under control. He can make different light show patterns with these photophores to communicate with others, to distract a predator or even lure their pray.
The eyes of a firefly squid has 3 pigments along with a double layered retina back in their eye. This helps the firefly squid to distinguish ambient light and bioluminescence light. This way they can see if the light is produced by other firefly squids or by predators. A big difference between other squids is that it's believed that the firefly squid is the only one with colour vision.
The reproduction of the firefly squid, once a year (March to June) millions of squids come together to fertilize and to drop their eggs in the Toyama Bay in Japan. The big reunion of these squids is one big light show that you can admire and it attracts thousands of tourists. Once the firefly squids have done their job, they die. The firefly squid has a one year life-cycle and once that year is over they die and wash up on the shore. This event is very important for other sea creatures and sea birds who enjoy eating the dead bodies of the firefly squid.
(By Lombroso [Public domain], via Wikimedia Commons)
Firefly squids are just as many other sea creature a delicacy in Japan and they're mainly caught when the firefly squids come together to mate.