Vargula hilgendorfii

Vargula hilgendorfii, also known as sea-firefly, is a bioluminescent species of ostracod crustacean. It is the only member of genus Vargula to inhabit Japanese waters; all other members of its genus inhabit the Gulf of Mexico, the Caribbean Sea, and waters off the coast of California. V. hilgendorfii was formerly more common, but its numbers have fallen significantly.