Pelagic zone

                                                                    The pelagic zone is the region of a body of water (lake, river, or ocean) that is not associated with the bottom (see benthic zone) or shore (see littoral zone).  This habitat zone is truly a three dimensional habitat space.  Some fish that occupy the pelagic zone never encounter the bottom or shore throughout their lives.  Because the pelagic zone is a nutrient poor environment, large fish have two basic strategies to get meals – either swim long distances in search of nutrient-rich prey (like many oceanic sharks and tunas) or drift with currents and eat nutrient-poor prey (like the Ocean Sunfish Mola mola). (fishionary.fisheries.org/pelagic-zone)

The pelagic zone is divided into layers based on light

 The pelagic zone is divided into zones based on light penetration from the surface:

• Epipelagic (sunlight; 0-200m)
• Mesopelagic (twilight; 200-1,000m)
• Bathypelagic (no light; 1,000-4,000m)
• Abyssopelagic (4,000m – ocean floor)
• Hadopelagic (deep sea trenches)