Are Sea Urchins Decomposers?

Sea urchins are classified as decomposers. These sea creatures decompose fungi so that other marine living creatures can survive in the environment. Harmful fungi can cause extreme conditions if sea urchins do not decompose them. This is the mechanism of nature, so sea urchins are known as the ocean or sea decomposers.

To survive, sea urchins consume decaying matter that they find floating or lying on the ocean floor. They hunt and eat live food. They also move in different places and eat decaying organic matter. This material usually covers rocks and other surfaces.

This article is based on detailed information about the topic: are sea urchins decomposers? These strong decomposers play a vital role in the environment. We can say that sea urchins are marine worms. Do not wait further. Let’s dive deep into the sea of insights about this lovely and incredible animal.

What Is a Decomposer Of The Sea?

The final organisms in the food chain are called decomposers. Since they feed on decaying vegetation and animals, these critters are often referred to as the “janitors” or “cleaning crew” of a given ecosystem. Sea urchins are one of them.

Authors from Biology Dictionary have clearly answered this query in the following words:

“Bacteria are known as the main decomposers of the sea. They are playing an important role in marine ecosystems. Echinoderms, crustaceans, mollusks, marine worms, and fungi are also called decomposers of the sea or ocean. Echinoderms like sea urchins and sea cucumbers are the main ones.” (Source)

Decomposers of the sea are generally different life forms compared to terrestrial animals and plants. These decomposers are well-adapted to their environment.

For example, sea urchins have special mouth parts, strong skeletons, and a well-adapted digestive system. They help them to survive on the cold and hot ocean floor.

sea urchin (2)

The animals of the sea have some obvious similarities with bacteria, such as structure, organelles, and protein-rich biochemistry. However, certain features of the animals and plants of the sea differ from bacteria in some ways.

Are Sea Urchins Decomposers?

Sea urchins are decomposers of the sea. Why are they called a decomposer? Sea urchins, like sea stars, are the main decomposers of the sea and ocean. The reason is simple; they feed on decaying matter.

According to Wikipedia:

“There are over 900 known species of sea urchins. Some sea urchins are segmented and form echinoderms. Some species, such as echinoderm algae or sea urchin flakes, are parasitic or contaminating.

Others are predators; some attack large animals such as clams and snails. Their tiny legs, eyes, and mouth help them capture and consume small plankton.

The urchins often contain a certain species of bacteria that they use to digest food in a way that other animals cannot. Without these bacteria, their environment would be mostly inedible.” (Source)

Most of the urchin species are small and solitary, but a few large ones also live on the seafloor. Some urchins are often called powerful decomposers.

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The writers of the “The Pacific Ocean Sierra and Angela” website have also classified the urchins as decomposers:

“Spiny invertebrates called sea urchins are both consumers and decomposers since they eat anything from other creatures and kelp to the thick layers of organic debris on rocks. This procedure shreds the organic materials so that microbes can digest them and release the resulting byproduct into the environment. Sea urchins are capable of reducing a kelp forest to little more than a pile of sand.” (Source)

Decomposers like sea urchins are everywhere. These decomposers maintain the grand circle of life. If we specifically talk about urchins, these are the most prevalent decomposers.

What Role Do Sea Urchins Play in The Ecosystem?

Sea urchins play a critical role in the ecosystem. They settle down the balance between coral and algae in the environment. When other herbivores (like parrotfishes and rabbitfishes) are absent from a reef, they can play a crucial role in maintaining the ecosystem.

According to the Reef Resilience organization, “Grazing algae and offering settlement space for corals are two ways in which urchins aid reef resilience and speed coral recovery following disturbances (such as storms or bleaching events).” (Source)

Similarly, to humans, urchins can get sick. Urchins are important herbivores, so managers may want to help replenish populations in areas where they’ve been depleted.

A coral reef’s ecosystem may potentially be negatively affected by urchins. The scraping effects of urchin eating can remove coral recruits, limit cover of critical coralline algae, and lead to unsustainable bio-erosion.

It is possible in cases when the processes of reef calcification are suppressed and/or urchin populations reach outbreak numbers. Among the marine ecosystem’s herbivores (or grazers), urchins are widely considered to be among the most effective.

Thus, a decline in these echinoderm populations causes an overabundance of algae growth. However, when urchin populations get too large, they can eat away at the sediment, leaving bare spots where plants formerly flourished (barren sites).

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Are Sea Urchins Producers or Consumers?

Sea urchins are known as primary consumers. They are not producers. This is because they maintain their energy by consuming primary producers.

Sea urchins are primary herbivores and consume algae, cucumbers, kelp, plankton, and other herbivores. These consumers are known for food dishes in shellfish seafood.

Is A Sea Urchin A Predator or Prey?

There is no doubt that sea urchins are prey for many animals and even for humans. These are popularized as a favorite food in Japan and many other countries. But “is a sea urchin a predator?” This is a little bit of a confusing question.

Let’s see what Wikipedia mentions about this query:

“While algae make up the bulk of a sea urchin’s diet, these animals also eat other animals. These animals are usually slow-movers (sessile).” (Source)

The above-mentioned research says that urchins are also predators. Their prey includes sea cucumbers and a wide range of invertebrates, such as mussels, polychaetes, sponges, brittle stars, and crinoids. That’s why they are also called omnivores and consumers.

sea urchin

Urchins are a good source of food (prey) for many lobsters, crabs, triggerfish, California sheephead, sea otters, and wolf eels. Usually, all types of urchins have long, sharp spines that deter predators.

Is Eating Sea Urchins Good for The Environment?

It’s good for the environment if we eat sea urchins and use them in various seafood-containing dishes. But why is it a good idea to eat sea urchins?

World Economic Forum’s senior writer, Charlotte Edmond, has described the reasons. These includes:

  • Inadequate regulation of marine environments has led to a surge in sea urchin populations.
  • They are cutting down kelp forests, leaving vast areas of ocean floor bare.
  • These kelp forests are a vital component of the carbon sink that aids in the fight against global warming.
  • It’s being cultivated by one company and sold to fine dining establishments as a gourmet delicacy.

Sea urchins are devastating marine ecosystems all around the world due to their venom, appetite, and rapid reproduction. What is the solution? Eat them.

Edmond has further stated:

The bull kelp population along a 350-kilometre stretch of the California coast has reportedly declined by as much as 90% due to an infestation of purple sea urchins, according to recent research.

In turn, this has led to a precipitous drop in the local populations of red abalone (a sea snail) and red sea urchin, both of which supported lucrative fishing enterprises.”  (Source)

Hence, the ecosystem needs natural predators to bring the sea urchin population as sustainable as possible. At this point, researchers are giving the idea of eating more and more sea urchins to save the aquatic environment.

sea urchin

What Would Happen If Sea Urchins Went Extinct?

The extinction of any living creature is obviously a threat to the ecosystem. Although sea urchins do not play a key role in the environment, they still do a great job eating harmful algae and deadly creatures.

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That’s the reason they are called opportunists. Because they eat anything available at the moment. Imagine if they all die?

The reefs will die, too, due to seaweed, kelp, and algae. Urchins work as grazers who check and balance the reefs and algae.

Frequently Asked and Questions (FAQs)

Is a red sea urchin a producer, consumer, or decomposer?

Red sea urchins are consumers as well as decomposers but not producers. These types of sea urchins feed on other animals and plants.

They eat dozens of kilograms of kelp each day. Thus, red sea urchins can easily finish a large quantity of kelp and algae.

Are urchins primary consumers?

Yeah, sea urchins are primary consumers. They consume the first-chain producers like kelp, plankton, algae, and even other animals like crustaceans, mollusks, marine worms, and many more.

They mostly feed on kelp and almost all-powerful primary consumers gain energy by eating kelp. Thus, these primary consumers feed on primary producers. It’s an interesting fact about urchins! 

Do any animals eat sea urchins?

Yeah, many animals eat sea urchins. Even wild birds also hunt urchins as a source of food and energy.

Sea stars, cod, lobsters, wolf eels, sheepshead, and foxes eat these. Sea otters love to eat sea urchins too.

What happens to sea urchins without sea otters?

No sea otters mean no kelp forests. Thus, this is directly linked to a healthy marine food web as kelp forests help to maintain the ecosystems too.

Otherwise, the population of sea urchins will increase at a rapid pace and sea urchins will finish the kelp forests from all over the world.


Sea urchins are an essential part of the aquatic environment. These marine animals are doing their job effectively for equilibrium in the ecosystems. But the increasing population of urchins is also alarming for forests and oceans. Thus, the globular Echinoderms population should be sustained for healthy surroundings.

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