What is the Marine Food Chain?

The marine food chain has much in common with the terrestrial food chain.

Table of Contents

Approximately 71% of the world consists of water, 97% of which is contained in the sea.

With such a large area to cover, it’s not strange to think a lot of creatures reside beneath the waves. These creatures are connected through food webs, a complicated web describing the consumption behavior within the marine ecosystem

To explain what’s happening under the sea, a food chain is a simpler alternative to the the food web. Generally, food chains can be divided into 4 levels: producers, herbivores, carnivores, and predators.


As the basis of all food chain, producers play an important role. Producers, or autotrophs, generate food from sources like sunlight and chemical reactions. The main producers of energy in the ocean are the photoautotrophs and chemoautotrophs.

Photoautotrophs turn sunlight and carbon dioxide into energy through photosynthesis. Does this sound familiar? This is the role of trees in the terrestrial food chain.

Since there are not a lot of trees in the ocean, this role is passed on to algae. Namely, the phytoplankton, single-celled microscopic algae distributed in the top layers of the sea. Phytoplankton provides energy for zooplankton either directly or through a microbial loop.

This is where the other part of the producers come in. The chemoautotrophs produce food from chemical reaction like decomposition rather than sunlight. Photoautotrophs are the backbone of the top layers of the ocean. Meanwhile, chemoautotrophs have the same role in deeper layers where the sun don’t shine.

Next, let’s talk about the eaters.


The second tier is herbivores or plant-eating animals. Since there is a lack of greenery in the sea, they turn to phytoplankton as a food source.

Although early herbivores are said to be invertebrates, current herbivores include a broad range of species. They are found within 4 groups of animals, invertebrates, fishes, reptiles, and mammals. This includes creatures such as zooplankton, mollusks, green turtles, parrotfish, dugong, and manatee.

These herbivores graze on the phytoplankton floating on the top layers of the sea. Their role in this chain is to keep the number of algae growing in the ocean under control. This mission ends when they get eaten by the next tier of consumers, the carnivores.


To meet our secondary consumers, we step into the “fish eat fish” world. Carnivores are the meat-eaters who eat other animals as their prey. Smaller carnivores, like sardines and squid, get their nourishment from herbivores. At this point, the food chain is already a complicated web since one creature can feed on multiple species. In turn, they are eaten by larger carnivores or predators.


Now we’ve arrived at our highest tier of the marine food chain.

Predators are very successful hunters. This level includes animals who prey on both herbivores and carnivores, like sharks, dolphins, and whales. The predators in this food chain are not limited to fish, they also include birds and mammals, like penguins, seals, and humans.

These animals are usually equipped with certain physical qualities which helps them hunt for prey. By utilizing these qualities, they become excellent hunters standing on the top of our chain.

They tend to breed slowly, which is concerning when we talk about endangered species due to the expansion of industrial fishing and ocean pollution.


So that’s it! Trees, herbivores, carnivores, predators, decomposition, and repeat. Not much different from its land counterpart, isn’t it?

Food chains are what keeps the ecosystem balanced. Excessive death of one species in the food chain can cause disruption of the food web and the ecosystem in the process.

More in Feature