original_query: What is the mesopelagic zone and how does it differ from other pelagic zones?
query: What is the mesopelagic zone and how does it differ from other pelagic zones?
answer: The mesopelagic zone, also known as the twilight zone, is the part of the pelagic zone between the epipelagic (photic) and bathypelagic (aphotic) zones.  It's defined by light levels, starting where only 1% of surface light penetrates and ending where there's no light (approximately 200-1000 meters deep).  Key differences from other pelagic zones lie in its light levels and resulting unique biological community adapted to low light conditions. 