Layers of the water column

The water column is a way of describing the different features found in seawater at different depths.  Scientists use these descriptions to classify how deep a section of the ocean is anywhere in the world.

Water column layers

The diagram below shows the layers of the ocean to a scale of 1 pixel to 10 meters.  To give an idea of the scale, a two storey house is around 1 pixel high or the size of a full stop.  At the bottom you can see how tall some famous buildings and places compare to the depths of the ocean.

Surface - 200m the Epipelagic zone

The only zone where enough sunlight reaches to support plant life, ideal for 90% of all ocean life. Also called sunlit or euphotic zone.

200m - 1000m the Mesopelagic zone
Light at this depth is faint and there is not enough to support photosynthesis. Animals at this depth include octopus, squid and hatchet fish. Some fish have extra large eyes to see and others produce their own light, called bio-luminescence. Also known as the midwater or twilight zone.

1000m - 4000m the Bathypelagic zone
No light penetrates this deep, so it is extremely cold and completely dark. About 1% of all ocean species lives in this zone. The sperm whale can dive to these depths searching for food, and might find giant squid, angler fish, gulper eel or snake dragon fish. Also known as the midnight zone.

4000m - 6000m the Abyssopelagic zone
Also known as the Abyss the name for this zone comes from the Greek word meaning 'no bottom', but actually three quarters of the ocean floor lies within this zone. Water temperatures border on freezing and there is no light. Very few creatures live this deep, but there are tiny squid and a few other small invertebrates.

6000m - 10,000m the Hadalpelagic zone
This zone is mostly composed of canyons and trenches. The deepest point in the ocean is in the Mariana Trench, off Japan, at 10,911m (35,797 feet). Despite the enormous pressure of around 1.1 tonnes per square centimetre (8 tons per square inch), life still exists here - flat fish were spotted on the first manned mission and invertebrates such as starfish and tube worms have also been seen.


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