What do krill eat?

In this brief blog, we will answer the question,”What do krill eat?” We will also explain what krills are and which animals feed on krills. We will as well explain if krill are the same as plankton. We will finally discuss the role of krill in the food chain & why they are important in the ecosystem.

What do krill eat?

Krill eat tiny phytoplankton (pelagic algae), fish larvae, algae and zooplankton. Krill primarily feed on phytoplankton and use their hair-like legs to be able to filter out the microscopic algae from the water.

What are krills?

Krills also known as Arctic krill are small ocean dwelling crustaceans in the same family as crabs, crayfish, shrimp, woodlice and lobsters. They usually grow to be about six centimeters in length and can live upto five years.

The main species of krill dwells in the Antarctic ocean. Krills usually congregate in large swarms of more than ten thousand individuals per cubic meters of water. 

What eats krills?

Krills are the prey for a variety of animals which include many penguins, blue whales, seabirds such as auklets & shearwaters. Many fish species such as salmon, flatfish, rockfish, sardines as well as squid also feed on krills.

Blue whales rely almost exclusively on krill to survive. They consume a large no. of krill approximated at about 4 tons of krills per day inorder to be sustained. When krills are abundant animals usually migrate thousands of miles to hunt and feed on krill.

Are krill the same as plankton?

To better understand this, we first need to know what plankton is. Plankton is a term that refers to the collection of creatures that act as the main food source at the bottom of the food chain for marine mammals. 

Plankton is grouped into 2 depending on its feeding mechanism. Phytoplankton are self feeding or scientifically called autotrophic. They manufacture their own food by photosynthesis or chemosynthesis. Some examples here are bacteria and algae

The second group comprises the zooplankton, and krills belong to this group. This group needs to consume other organisms to generate energy. Examples in this category are single celled organisms and small animals.

Krill are the most dominant as well as the most ecologically important zooplankton and they usually survive by feeding on phytoplankton.

Therefore krill are planktons but as you may have learned from above, not all plankton are essentially krill. Krill serve as the main planktonic food source for the marine mammals. 

What is the role of krill in the food chain & why are they important?

Krill usually feed on phytoplankton which are the single celled and microscopic plants that usually drift near the surface of the ocean utilizing CO2 and warmth from the sun for growth. 

Krill in turn are the main and exclusive food source for many marine animals including different types of fish, birds and whales. In essence, many oceanic life forms rely on krill in order to survive.

There are plenty of krills and they make up a significant percentage of the ocean’s biomass with the biomass of just one species the Euphausia superba, estimated at 379 million tonnes. That makes up a great amount of food and in turn ranks them amongst the species with the greatest total biomass.

When krill feed on plankton they as well assist in conversion of them into a food source for animals that are higher on the food chain and that cannot consume such small organisms.

As a result of many species of krill migrating to the ocean’s surface to feed on phytoplankton and back to the inner depths at night, they act as food for both surface and deep sea predators. This makes a very vital food source throughout the ocean ecosystem.

You can learn more about the importance of krill in the biogeochemical cycles here.


In this brief blog, we have answered the question,”What do krill eat?” We have also explained what krills are and which animals feed on krills. We have explained if krill are the same as plankton. We have finally discussed the role of krill in the food chain & why they are important in the ecosystem.



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