Firefly squids live in the western pacific ocean mostly in the waters around Japan. These little squids which only average about 2.4 inches in mantle length live near the seafloor.
Firefly squid
During the day at depths of more than 656 feet at night they migrate towards the surface and remain at depths of around 164 to 328 feet it’s their appearance near shore. During the breeding season that brings about their popularity specifically it’s the female firefly squids who during the months of March to may move inland and fill the shore waters.
Toyama bay is especially a hot spot for catching these glowing visitors yes glowing firefly squid like the animals from which they get their common name are bioluminescent it’s estimated that upwards of 90 of animals living in the mesopelagic or twilight zone of the ocean, are able to produce light originally scientists predicted that firefly squids produced light via a symbiotic relationship with light-emitting bacteria but it’s now known that these little cephalopods create their own light.
Why do Firefly squids glow?
There are three main centers for light production on a firefly squid their mantle around their eyes and on the tips of some of their arms the first two are a weak type of light and described as similar to distant stars in the nighttime sky. But the light produced from this squid’s arms is so bright it can even be seen in a lit room.
Plus they create pulsating patterns with their light emission hence the common name firefly squid though in japan they’re known as hotaru ika. Firefly squid are especially important in japan because they’re captured in droves during the breeding season upwards of 4 000 tons of firefly squids may be taken in a single year and used as food.
Firefly squids make their way inland during this time to release their fertilized eggs ninety-nine percent of those caught throughout this season are actually females and in fact the male life cycle of the firefly squid, is currently unknown. A female firefly squid will travel towards the shore laden with several hundred to more than ten thousand fertilized eggs.
She’ll release these eggs in gelatinous strings reaching over three feet in length the eggs will hatch within one to two weeks depending on the temperature of the surrounding water and like other cephalopods. The mothers will die shortly after firefly squid larvae and adults are predated by fish such as salmon as well as northern fur seals but the young that survive will make the same journey.
The following year well the females will anyway who knows what the males do some cephalopods like cuttlefish are colorblind even though they produce brilliant arrays of colors but firefly squid are believed to be able to see color. They have more receptors in their eyes for seeing color than other cephalopods.
Firefly squid also lack a cornea meaning their irises are in direct contact with the surrounding seawater and here I was thinking it hurt my eyes to have them open underwater in the ocean.
Reference: Firefly squids video
