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Decomposers in the Ocean: Role and Examples

Decomposers in the Ocean: Role and Examples

As a part of an ecosystem, all decomposers are important in sustaining the food chain. In this ScienceStruck article, we discuss the importance of decomposers, and the various creatures which perform this role in the vast oceanic zones of our planet.
Anuj Mudaliar
Last Updated: Apr 20, 2018
Quick Fact
Recent research shows that macroconsumers such as detritivores work on breaking down dead animal and plant matter. This is why the newer definition of decomposers includes a wider range of creatures than before.
Decomposers are the living/biotic beings which occupy the last stage of the food chain. These creatures are considered to be the cleaning crew of any ecosystem as they live on organic wastes of dead plant and animal matter. The ocean biome, consisting of open waters, reefs, estuaries, and shores covers over 70% of the earth's surface. Therefore the number of plants and animals in the ocean zones is very extensive, compared to that of the land biome, which means that oceanic decomposers are also larger in number and variety.

The availability of all creatures depends on the sunlight and temperature in the water. Therefore, the number of decomposers in the tropical oceans such as the Pacific ocean, is much higher compared to that in the cooler counterparts like the Atlantic and Arctic oceans.
Examples of Decomposers in the Ocean and their Role
Bacteria
Marine Bacteria
Like terrestrial ecosystems, the ocean too relies very heavily on bacteria for most decomposition. Since bacteria are present everywhere in the marine environment, they start acting on plants and animals as soon as death occurs. They turn the organic matter into basic nutrients, which feed plant life and microscopic animals in the ocean. Since they are invisible to the naked eye, bacteria are known as microdecomposers.
Fungi
Marine Fungi
Sea Mushrooms on Coral Reef
Many varieties of fungi grow in the oceans of our planet; most are microscopic in size, and others are bigger than small animals. One can usually identify the action of underwater fungi, as they grow a jelly-like, slimy layer around the dead organic matter. Larger varieties filter the surrounding water for organic particles, which are turned into basic nutrients, similar to the bacteria. However, only fungi and bacteria act as decomposers in the colder waters of the world, as the macro decomposers mentioned below cannot survive in this extreme environment.
Marine Worms
Christmas Tree Worms
Christmas Tree Worms
Feather Duster Worm
Feather Duster Worm
Fireworm
Fireworm
Marine Worm
Marine Worm
The oceans have a number of worm varieties, which slowly crawl around the seabed, while consuming organic waste, and turning it into useful material for other plants and animals. Due to their larger size, these creatures are known as macrodecomposers. Marine worms can be of different colors, and shapes, which is the reason why some species are popular as aquarium pets. A common variety known as feather duster worms or Christmas tree worms, are found in abundance in shallow waters. They are largely sedentary in nature, and they collect food, by building tubes of sand and shells around their bodies, and spreading feathery appendages in the water, which filter floating organic matter for decomposition.
Echinoderms
Sea Urchins
Sea Urchins
Sea Star
Sea Star
Sea Cucumber
Sea Cucumber
Sea urchins, sea cucumbers, sea stars, etc., are creatures which are known as echinoderms. These creatures are often characterized by their colorful, symmetrical bodies. Although, some of them actively hunt and eat other animals and plants, echinoderms also feed on decaying organic matter, which coats rocks, and other stationary surfaces in the ocean, before releasing it in a simpler form, which is why they can be considered as macrodecomposers.
Crustaceans and Molluscs
Porcelain Crab
Porcelain Crab
Banded Shrimp
Banded Shrimp
Lobster
Lobster
Similar to the echinoderms, many molluscs and crustacean creatures like clams, mussels, crabs, shrimp, etc., are also macrodecomposers, which feed and convert decaying organic matter floating around in the seawater, thereby sustaining the food cycle, and maintaining the underwater ecosystems.
The variety of living creatures in a marine environment is very diverse, as these creatures have adapted to a wide range of living conditions. In this ecosystem, it is important that the food chain remains balanced, for the survival of life. While producers such as phytoplankton are important for providing food to consumers like fish, it is equally important for the decomposers to clean up and convert dead matter into nutrients vital for the producers' survival.