Females bear litters of up to five pups in early summer; the newborns measure long and are lighter and more uniform in color than the adults. Sexual maturity is reached at a length between for males, and at around for females. Human interactions The shock from the Japanese sleeper ray is strong but not life-threatening to humans. There is an observation of a ray that reacted to being touched with a camera by rubbing its back against the camera port, suggesting that it may actively defend itself if disturbed. The Japanese sleeper ray adapts poorly to captivity. This and other species of electric rays are used in biomedical research because their electric organs have an abundance of ion channels and acetylcholine receptors, and can serve as a model for the human nervous system. Though little specific data are available, the Japanese sleeper ray is believed to be caught incidentally in shrimp trawls and other demersal fishing gear throughout its range. It is not utilized economically; however, electric rays tend not to survive being caught and discarded, and shrimp trawling is known to have caused marked population declines in other electric ray species elsewhere. Given the high intensity of fishing activity off East Asia, the International Union for Conservation of Nature (IUCN) has assessed this species as Vulnerable. References japonica Fish of Japan Fish of Korea Marine fauna of East Asia Vulnerable fish Vulnerable fauna of Asia Taxa named by Coenraad Jacob Temminck Taxa named by Hermann Schlegel Japanese sleeper ray Strongly electric fish