Bristle Worms

[Aquattro]

I don't think a worm would eat a shrimp. The shrimp probably molted and is hiding until it's shell hardens.
And yes, the shrimps only ate the small bite sized worms, not the giant ones. Also, I don't think the average 1/2 inch bristle worm grows to 6 feet. I think the big ones are different species.