The firefly squid (Watasenia scintillans), also commonly known as the sparkling enope squid or hotaru-ika in Japan, is a species of squid in the family Enoploteuthidae. It is the sole species in the monotypic genus Watasenia. These tiny squid are found on the shores of Japan in springtime during spawning season, but spend most of their life in deeper waters between 200 and 400 metres (700 and 1,300 feet; 100 and 200 fathoms). They are bioluminescent organisms and emit blue light from photophores, which some scientists have thought could be used for communication, camouflage, or attracting food, but it is still unclear in the scientific community exactly how this species uses their bioluminescence. The firefly squid is a predator and actively hunts its food, which includes copepods, small fish, and other squids. The lifespan of a firefly squid is about one year. At the end of their lives females return close to shore to release their eggs, and then die shortly thereafter. This mass migration of firefly squid to the shore is amazing business for Japanese fishermen, and during spawning season many go out to the bays to collect the dying squid. Many more also visit Japan during spawning season to see the bright blue light created from the firefly squid's bioluminescence light up the bay, making their spawning season not only a fishing opportunity but also a tourist attraction.

A shoal of squid.