@ bearfoil
I think the answer to your question is more to do with scavengers....
Bathypelagic Zone - 1000 m down to 4000m
A surprisingly large number of creatures are to be found in this region -.
even Sperm whales have been known to reach depths of 3000m.
Abyssopelagic Zone - 4000m to 6000m
Basket stars, small squids, starfish, shrimp, Grimpoteuthis, etc
Life at these depths is adapted to survive on whatever descends from
the surface - usually at the end of a life cycle.