Hotaruika Museum

Firefly squid spend their lives in deep water and come into Toyama Bay in spring to spawn. They are a few centimetres long, they have light organs down the arms and body, and when disturbed they emit a strong blue light. In Namerikawa the bay's shelf comes close enough to shore that they arrive in enormous numbers, and the town has built a museum around them.

The centrepiece is a darkened room where live squid are handled in a tank and light up on cue, several times a day. That only works between late March and the end of May, when the animals are actually in the bay and can be caught fresh each morning; outside the season the show uses bioluminescent plankton instead, which is interesting but is not the same thing. Boats also run pre-dawn to watch the fishing itself. It is the only place in the world set up to show you this.

The reason this particular stretch of coast is unusual comes down to underwater geography. Just offshore, the seabed drops away steeply into one of Toyama Bay's deeper trenches, so firefly squid rising from several hundred metres down to spawn pass close to shore rather than staying far out to sea. Set nets anchored a short distance out intercept them on this nightly migration, which is what allows boats to bring live squid back before dawn rather than after a long voyage — proximity, rather than any special abundance of the species, is what makes Namerikawa the place people come to see them.

Beyond the glow-in-the-dark tank, the museum works through the squid's short life cycle using models, video, and preserved specimens: how the light organs are arranged along the arms and underside, how the glow is thought to function as camouflage against sunlight filtering down from above and possibly as a signal during spawning, and how the animals die shortly after reproducing, their bodies washing up on nearby beaches in years of heavy landings. A separate aquarium section in the same building houses other Toyama Bay species that share the same deep, cold-water habitat, giving some context for why this stretch of coast supports such an unusual mix of marine life so close to shore.