Scientists discovered three new deep-sea shark species that glow in the dark.
The sharks live in the depths, in an area known as the twilight zone of the ocean, between 200 and 1,000 metres deep, where sunlight cannot reach.
The sharks, whose bellies glow in the dark, can appear backlit against the surface of the water.
The scientists said the discovery could help us to better understand life in the deep sea – one of the least-studied ecosystems on the planet.
Despite the findings, more research is required to understand why the sharks are luminescent, particularly the kitefin shark, the largest of the species found.
It is the largest-known luminous underwater creature.
Researchers speculate that the slow-moving shark uses its natural glow to illuminate the ocean floor as it hunts for food, or to disguise itself while it approaches prey.