Depth: Surface - 200m
When we think of the ocean, the images that usually come to mind first are those of sunlit reefs filled with healthy corals and plentiful, vibrant fishes swimming in brilliantly blue, tropical waters. However, ecosystems like this actually make up less than 1% of the Earth's surface and less than 2% of the total ocean floor. Most of the ocean exists beneath the photic zone (the zone where light can penetrate) and thrives without the energy of our sun.
The oceans are divided into zones, based on depth. The uppermost zone is the Epipelagic Zone. The iconic animals contained within this sun-filled zone include vaquitas (the smallest whale), dolphins, orcas, turtles, schooling tropical fishes and huge expanses of colorful coral reefs. Below this is the Mesopelagic, or Twilight Zone.
Depth: 1000 - 4000m
Extending from 1000 meters down to 4000 meters, the Bathypelagic, or Midnight Zone, is a zone where no sunlight penetrates. Animals here rely on eating falling detritus (organic waste) as well as eating one another to survive. Cachalots (Sperm whales) hunt in these depths for giant squid, and common animals found here include vampire squid, anglerfish and crustaceans.
Depth: 4000 - 6000m
The Abyssopelagic Zone is from 4000 - 6000 meters deep and is characterized by freezing temperatures, intense pressure and is completely aphotic (no sunlight ever penetrates). Creatures that have adapted themselves to this unforgiving environment include some species of squid and octopus, as well as many types of brittle stars and echinoderms. Yet there is an even deeper layer to our oceans.
HADAL ZONE (TRENCHES)
Depth: 6000 - 11,000m
The Hadal Zone contains our deep ocean trenches. The forbidding Hadalpelagic Zone extends from 6000 meters (19,686 feet) to the very deepest point on our plane, the Mariana Trench near the island of Guam. This trench drops down to an astonishing 10,911 meters (35,797 feet). Pressures down there reach eight tons per square inch; the water temperature remains just above freezing. However life exists even here, and animals such as tube worms, starfish and other invertebrates that thrive at these depths remind us of the biological diversity and resilience of our wonderful water planet.