overviewVargula hilgendorfii, sometimes called sea fire, is an ostracod crustacean species, one of three bioluminescent species known in Japan as umi-hotaru (海 蛍). It is the only member of the Vargula genus to live in Japanese waters; all other members of the genus waters off the coast of the Gulf of Mexico, the Caribbean Sea, and California. V. hilgendorfii used to be more common, but their numbers have dropped significantly.
A small crustacean with bivalves, shell-like, luminescent shellfish (intermediate) subfamily Cyprididae. About 3mm long. The trunk is completely white on both sides, covered with a milky-white shell. The left and right shells are connected by closed muscles and hinges at the back, and there are deep cuts that provide antennal edges. They have compound eyes. Hermaphrodite. Luminescent substances secreted from glands in the upper lip are released into sea water with stimulation and emit light. Prolific from summer to autumn on the Pacific coast of Japan. During the day it dives into the sandy mud, but at night it floats and gathers in the carcass. Using this, the fish meat placed in a net or the like is hung from the quay or pier to the sea at night, lifted after a suitable time, shaken vigorously in a container containing sea water and dropped to the bottom of the ship. It can be collected in large quantities. It emits intense light when ground with water after drying in the sun, immediately after collection. If this dried marine firefly is stored in a moisture-free desiccator or similar, an appropriate amount can be removed and light emitted at any time. The length of Pyrocypris Noctiluca is about 2mm, white, and the strong shell protrudes is about the rear and radiates light. Body length of Euphilomedes japonica, whose shell surface is fluttered, about 1.5 to 2.5 mm, small hairs are formed ventrally around it and it does not emit light. There are other types in the same section.