Marine Biome
Written by: Robert Wildermuth
Illustrated by: Sabine Deviche

show/hide words to know

Current: the part of the air or water that is moving constantly in a single direction.

Debris: loose or scattered pieces of floating material.

Gyre: a circular current that spins water around the ocean, like a spinning washing machine... more

Ocean basin: a large area or section of the ocean.

Pelagic: the area of the ocean where animals float without touching the bottom or dry land... more

Symbiosis: a relationship between two different organisms that can be, but is not always helpful for both organisms... more

The Ocean Deep

Earth from space

The open ocean biome is the largest biome on Earth. Click for more detail.

You are floating, face up, in the middle of a big swimming pool. With your eyes closed and your ears under the water, you don't see or hear much. All you can feel is your body bobbing up and down on the surface.

You almost forget that there are sides or a bottom to the pool. In the ocean, there is a place where this feeling goes on and on: the open ocean marine biome.

The open ocean can appear boring with only water and sky visible, but these two pieces interact to make an interesting and changing ecosystem.

Without mountains or other features to get in the way, the environment in the open ocean often depends on the direction the wind and water move.

For example, the weather pattern El Niño happens when wind surface waters in the South Pacific Ocean start flowing east, turning the surface waters warm.

El Nino and La Nina sea temperatures

Ocean weather systems can change the Southern Pacific Ocean ecosystem. Click for more detail.

Ocean algae and plankton do not fare well in warm water. When these organisms die, there is no more food for larger animals. This weather pattern can change the structure of the entire ecosystem within a few months.

The deep ocean covers over 45% of the entire globe. If you were dropped in the middle of the open ocean biome you might have to swim hundreds of miles to reach dry land. Hopefully you learned to float because much of the open ocean is over 2 miles, or 3.2 kilometers, deep.

The water is so deep here that unlike other biomes, the deep ocean is often studied vertically (from top to bottom) rather than horizontally (from side to side).


This Man-O-War may look like a jellyfish, but it's not even a single animal. Click for more detail.

In this biome light only reaches the first couple layers of the deep ocean. The rest exists in complete darkness.

This strange environment hosts many animals you might not even recognize as living creatures. And instead of plants, you’ll find mostly animals here because much of the open ocean is far from the sun’s reach where plants cannot grow.

The animals living in this world can spend their entire lives without ever touching a firm surface. Imagine drifting around your whole life, only heading whichever direction the currents take you.

Additional images via Wikimedia Commons. Underwater image by Felipe Skroski.

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Bibliographic details:

  • Article: Observing the Open Ocean
  • Author(s): Robert Wildermuth
  • Publisher: Arizona State University School of Life Sciences Ask A Biologist
  • Site name: ASU - Ask A Biologist
  • Date published: November 18, 2014
  • Date accessed: April 17, 2024
  • Link:

APA Style

Robert Wildermuth. (2014, November 18). Observing the Open Ocean. ASU - Ask A Biologist. Retrieved April 17, 2024 from

American Psychological Association. For more info, see

Chicago Manual of Style

Robert Wildermuth. "Observing the Open Ocean". ASU - Ask A Biologist. 18 November, 2014.

MLA 2017 Style

Robert Wildermuth. "Observing the Open Ocean". ASU - Ask A Biologist. 18 Nov 2014. ASU - Ask A Biologist, Web. 17 Apr 2024.

Modern Language Association, 7th Ed. For more info, see

The open ocean seems to be an endless world of water.

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