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Thursday, Sept. 11, 2003

ANIMAL TRACKER

Firefly squid


* Japanese name: Hotaru ika
* Scientific name: Watasenia scintillans
* Description: With a body length of just 4-6 cm, these squid are small but perfectly formed. Squid have a streamlined head and body, with eight arms and two tentacles around the head. (Octopi don't have tentacles, which are longer than arms and have suckers only at the tips.) Squid have a hard, penlike structure in the body, the remnant of the shell that the animals they evolved from used to support the body. Like other cephalopods (marine mollusks also including octopus and cuttlefish), squid have a well-developed head, a large brain and eyes with a structural design superior to those of vertebrates. The arms and tentacles are prehensile (they can grip things in a similar way to hands). All squid move by jet propulsion, by squirting water out of a cavity in the body, but firefly squid are unmistakable -- they also emit bright light from 1,000 individual light cells all over their bodies.
* Where to find them: During the day, 200 to 600 meters below the surface of the sea. At night they come up to feed.
* Food: Shrimp, crabs, fish
* Special features: The tips of the tentacles of the firefly squid have light-producing organs called photophores, which are flashed on and off to lure small fish into striking range. But the squid can also emit light from the rest of its body. During the spawning season (March to May), they come close to shore and can be seen, famously, in Toyama Bay, Toyama Prefecture, designated a Special Natural Monument. The V-shaped canyon in the bay where the squid gather has a current that pushes the squid to the surface. Along the coast from Uozu to Mizuhashi in Toyama City is a good place to see them. What is the function of their phosphorescence? It might disrupt the squid's outline and confuse potential predators. It might also be used to attract prey but, more likely, the glowing lights attract mates, as the firefly squid is the only cephalopod known to have color vision..



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