Benthos facts for kids

Benthos refers to all the amazing plants and animals that live on, in, or near the bottom of a sea, lake, or river. These creatures are called benthic organisms. They can be found in shallow areas, like rock pools along the coast, or in the deepest parts of the ocean.

Benthic organisms are different from plankton, which are tiny living things that float or drift in the water above the bottom. Benthos are usually attached to the bottom, burrow into it, or crawl along it.

What is Benthos?

Benthos includes a huge variety of life forms. Think of anything that lives on the seafloor or lakebed. This can be tiny creatures you can barely see, or much larger animals like crabs and starfish.

Where do Benthic Organisms Live?

Benthic organisms live in many different places:

• Shallow waters: In places like rock pools, you can find small crabs, seaweed, and snails clinging to rocks. Even though these spots are only a few inches deep, the animals living there are still considered benthic because they are on the bottom.
• Deep ocean: Many unique creatures live in the dark, cold depths of the ocean floor. These areas are often far from the surface and sunlight.
• Lakes and rivers: Just like in the ocean, the bottoms of lakes and rivers are home to many different benthic animals and plants.

Types of Benthic Organisms

Benthic organisms can be divided into two main groups:

• Zoobenthos: These are the animals that live on or in the bottom. Examples include crabs, starfish, sea urchins, clams, snails, and many types of worms. Some zoobenthos burrow into the mud or sand, while others crawl on top.
• Phytobenthos: These are the plants and plant-like organisms that live on the bottom. This group mainly includes algae and seaweed that need sunlight to grow. You'll find them in shallower waters where light can reach the bottom.

Why are Benthic Organisms Important?

Benthic organisms play a very important role in aquatic ecosystems:

• Food source: Many fish and other marine animals rely on benthic organisms as a major food source.
• Cleaning the environment: Some benthic animals, like clams and mussels, filter water, helping to keep it clean.
• Nutrient cycling: Organisms that live in the sediment help to break down dead material and recycle important nutrients back into the water. This process is vital for the health of the entire ecosystem.
• Habitat creation: Some benthic organisms, like corals and seagrasses, create complex habitats that provide shelter and food for many other species.

Images for kids

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  Seaweed and two chitons in a tide pool

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  Benthic diatom
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  Example zoobenthos A variety of marine worms Plate from Das Meer by M. J. Schleiden (1804–1881)
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  Seagrass

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  Echinoderms

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  Sea squirts

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  Aquatic worm, snail, midge larvae and amphipods

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  Foraminiferan

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  Gastrotrich

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  Copepod

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  Tardigrade (water bear)

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  Diatoms

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  Ciliate

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  Dinoflagellates

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  Elphidium a widespread abundant genus of benthic forams

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  Heterohelix, an extinct genus of benthic forams

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  Darkfield photo of a gastrotrich, 0.06-3.0 mm long, a worm-like animal living between sediment particles

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  Armoured Pliciloricus enigmaticus, about 0.2 mm long, live in spaces between marine gravel

See also

In Spanish: Bentos para niños