A species from Kaminar who evolved as prey.
Kelpiens are a tall, thin humanoid species from the planet Kaminar. They have threat ganglia, organs on the back of the head that extend when they sense danger, which suited a people who for generations lived as prey for the other species of their world, the Ba'ul.
For centuries the Ba'ul culled Kelpiens who reached a stage of life called vahar'ai, which the Kelpiens believed ended in madness and death. Saru, the first Kelpien to join Starfleet, served as science officer and first officer of the USS Discovery. In the second-season episode The Sound of Thunder, he learned that vahar'ai actually frees Kelpiens from fear and that, long ago, Kelpiens had hunted the Ba'ul, who culled them out of fear of that happening again.
With help from the Red Angel, all Kelpiens on Kaminar went through vahar'ai and the balance of power ended. Saru later became captain of Discovery. In the thirty-second century, the Kelpien Su'Kal turned out to be at the centre of the Burn.