Mesopelagic

In the thermocline, temperature decreases rapidly from the mixed upper layer of the ocean (called the epipelagic zone) to much colder deep water in the thermocline (called the mesopelagic zone).

Females feed on squid in the mesopelagic zone, which is below 650 feet, it is surmised to avoid their predators.

For those animals living in the mesopelagic zone, where some light downwells from the surface, a visual predator looking up at them could see a silhouette.