Sreen

Sreen were a type of animal that existed on the planet Bajor. They were an eel-like creature that lived within deep underwater burrows.

In 2378, Jean-Luc Picard was attacked by an underwater animal and dragged away before James T. Kirk's eyes. When he returned to the surface, he asked the Bajoran's what type of animals lived in the waters which they stated were only Sreen and dismissed them as being the cause of the attack as they left Humanoid's alone.