(1) EPIPELAGIC ZONE
: Sunlight easily penetrates this zone, making living plants plentiful.
Ichtyofauna of epipelagic zone
. Israel Program for Scientic Translation, Tel Avid.
At 200 meters deep, the diver would cross from the surface realm (called the epipelagic zone
), where there is enough sunlight for photosynthesis, to the twilight realm (called the mesopelagic zone), where enough sunlight penetrates for vision, but not for photosynthesis.
The use of transparency for crypsis by cranchiid squids relieves them of some of the selective pressure associated with the well-lit epipelagic zone
(Seapy and Young, 1986; Seibel et al., 1997; Johnsen and Widder, 1998).