Wednesday, March 21, 2012

Similar to a Million Fireflies... in the Ocean

Bioluminescence of Firefly squid
Watasenia Scintillans, also known as the firefly or sparking enope squids, are cephalopods that have the ability to produce bioluminescence due to their photophores.  These photophores, covering their entire body, are controllable and are used as a lure for prey, a distraction of predators and as a means of communication with others.  The largest photophores are found near the eyes and on the tentacles.  The eyes of this squid contain double layered retinas and three different light-sensitive cells (or pigments), which may allow them to see simple color, and to
Firefly squid without bioluminescence
further distinguish between fellow firefly squid or a predator.  This is rare, and is not normally an ability of other squids because other squids only have one visual pigment.  They are relatively small, reaching a maximum length of about 7 cm.  The firefly squid resides in the Western Pacific Ocean near Japan and lives in depths ranging from 200 - 400 m.  During the day, firefly squids stay near the deeper parts of the ocean to avoid any predators.  However, at night and during the time of spawning, they head to the shallower parts.  At night they head to the surface to feed.  The life span of a firefly squid is, sadly, only a year.  This is because once they reproduce, the squids die.  On the bright side (ha), they produced many eggs to stabilize, or increase, their population.  During this time of reproduction, between March and May, the squids gather in Toyama Bay in Japan, and perform a kind of "light show" from their flashing of the photophores, which can occur in unison or alternately.   The light produced is a deep blue color.
Namerikawa Museum
Also during this season, the squids are heavily fished.  Predators of the firefly squid include sperm whales, sharks, larger fish, other squid, humans.  The firefly squid is a delicacy in Japan, and is referred to as "Hotaru-ika." 
Namerikawa is the home of the only museum, in the world, dedicated to firefly squids.  (The website for this museum is completely in Japanese and is not helpful for further description of the museum.)  Tourists interested in seeing this phenomenon are able to sign up for a 3AM sightseeing boat trip!  (3AM!)

The Japanese Dish, "Hotaru-Ika"

I was unable to find a video on youtube that I actually liked, but this works too.

Source 1
Source 2
Source 3
Source 4


  1. I was going to do my post on squid but you beat me to it! I think your post is so interesting though. I have never heard of the firefly squid before, and I didn't know that there were some squid that could see any color. It is neat that they have that extra ability to help them distinct a predator.

  2. That is very interesting about their vision! I think it would be so cool to see these creatures. They seem so unique compared to other squids, leading to the idea that there are many species of squid each very different from one another.

  3. There was a lab at USC when I did my PhD that studied a bioluminescent squid from Hawaii. They would need to travel there every now and then to collect live specimens. Tough life.

  4. I'm just going to add on to Katelyn's comment on how it is interesting that these squids are different than the rest in their ability to see simple color. I thought it was really cool that they are able to use this adaptation to distinguish between other firefly squid and predators. This would make sense that they would use this during the reproductive season when they have their "light shows" that produce a very deep blue color.