The life cycle of the eel has long puzzled scientists. Even the Greek philosopher Aristotle pondered the question of where eels came from, deciding that they sprang up spontaneously from the mud.

The eels are “highly sensitive to light” and ... Researchers said they named the new species after “the ancient Greek god of the underworld,” Hades, because its preferred habitat ...

In a murky river of southern Japan, a slimy creature with “pointed” teeth burrowed into the mud. Its shadowy habitat and cryptic looks helped it go largely unnoticed and, when occasionally found, be ...