Benthic Definition (With Examples)

What Does Benthic Mean?

The term benthic refers to the benthic zone. Benthic zone is the ecoregion at the bottom of water, usually ocean or lake. It is often full of live organisms that are called benthos and include microorganisms like bacteria and fungi as well as larger invertebrates.


  • The term benthos was coined by Haeckel in 1891
  • Many organisms that live in the benthic zone are permanently attached to the bottom
  • Benthos are the organisms that live in the benthic zone
  • Sources of food for benthos come from above in the form of marine snow
  • The amount of material sinking to the ocean floor can average 307,000 aggregates per m2 per day
  • Many benthic organisms have retained their historic evolutionary characteristics

Marine snow is a continuous shower of mostly organic detritus (dead particulate organic material) falling from the upper layers.

Why Is Benthic Zone Important?

Although people usually think that ocean or lake bottom is barren, it is oftentimes brimming with life. Of the marine species, 98% live on or in the ocean floor. Benthic habitats can play an important role in maintaining water quality by cycling nutrients, and contributing to the removal of contaminants.

Benthic organisms are also important because they’re serving as food sources for higher-level consumers.

What Lives In The Benthic Zone?

We’ve already learned that living organisms living in the benthic zone are called benthos and that most of them are microorganisms and invertebrates. Many of these organisms have adapted to live on the substrate and cannot survive in the upper parts of the water column because they need deep-water pressure.

Benthos are divided into epifauna and infauna, or those that live on the surface of the ocean floor and those that live burrowed into the ocean floor.

Examples Of Benthic Organisms

Examples Of Benthic Organisms
Examples Of Benthic Organisms

Seabed can be very vibrant and teeming with life. For example, filter feeders like sponges and bivalves, dominate hard, sandy bottoms. Deposit feeders, such as bristle worms, populate softer bottoms. Fish, such as dragonets, as well as sea stars, snails, cephalopods, and crustaceans are important predators and scavengers that feed on sea stars, oysters, clams, sea cucumbers, brittle stars and sea anemones.

There’s never a dull moment in the benthic zone.

How Deep Is The Benthic Zone?

Because the benthic zone begins at the shore line and extends downward along the surface of the continental shelf out to sea, the benthic zone can start as deep as a few inches an endup being 19685 inches (6000 metres) deep.

Benthic zones by depth:

  • Epipelagic (less than 200 meters),
  • Mesopelagic (200–1,000 meters),
  • Bathyal (1,000–4,000 meters),
  • Abyssal (4,000–6,000 meters),
  • Hadal (below 6,000 meters).
By Chris huh(Original text : K. Aainsqatsi) / K. Aainsqatsi – self-made(Original text : self-made), Public Domain,

How Much Pressure Is In The Benthic Zone?

Because the depth of the benthic zone varies greatly, so does the pressure. It can be very small in the shallows only to end up a 1,000 times stronger than pressure on the surface.

Organisms that have adapted to high-pressure environment are oftentimes much bigger than their counterparts above. They benefit from dissolved oxygen content that is quite high and enables them to grow, grow, grow.