Question: What sea zone (sun light, twilight and midnight zone) has the most living organisms in?

Lidunka Vocadlo answered on 15 Jun 2015:

There is a zone called the epipelagic zone which extends from the surface to about 200 metres – this is where most of the life is. Below that not enough sunlight gets through the water, so there is no life. However, there are some creatures that thrive on the stuff that comes out of hot vents at the bottom of the oceans which have only recently been discovered.