荧光动物，日本（摄影：Paul A. Zahl）

海萤是一类介形虫，生活在日本滨海水域或沙滩。它的透明壳体内，遇到扰动时会释放蓝光。据传，二战时期，日本曾大量捕获这些小虫子供士兵夜间阅图览物之用。

The transparent shells of tiny Cypridina hilgendorfii, found in the coastal waters and sands of Japan, hold a creature that emits a luminous blue substance when disturbed. During World War II, the Japanese harvested these creatures for soldiers to use when reading maps and messages at night.

 (Photo shot on assignment for "Nature's Night Lights—Probing the Secrets of Bioluminescence," July 1971, National Geographic magazine)