Krill fish don’t look anything like fish nor are they fish.  Despite that, they are called fish or simply krill.  These tiny crustaceans belong to the Euphausiacea order and they are found in oceans all over the world.

Krill are small aquatic animals but despite their tiny size, they are an incredibly important food source for many huge aquatic animals such as the blue whale and these animals.  Krill might be small but their huge numbers make them one of the biggest animal species in the sea.  One species of krill, the Antarctic krill, has an estimated biomass of about 397,000,000 tons.  And that is just one species.

There are 85 known species of krill found in the oceans which include two main species:  the Euphausia species that is larger and the Bench Euphausia amblyopia species that is found deep under the ocean at about 3,330 feet below sea level.

What Do Krill Eat?

Krills are quite small and as such, they need to feed on small food pieces at a time.  Despite the fact these aquatic animals are barely bigger than a paperclip, they feed on a huge variety of foods and large swarms of krill can consume a lot of food just because of the sheer size of their families.

Krill are filter feeders.  They have fine combs that they use to filter out tiny food particles from water.  Most species of krill are omnivorous and feed on both animal and plant matter.  Here is a quick look at their main food sources:

Phytoplankton

This is one of the main food sources for krill.  Phytoplankton is microscopic marine algae.  This food source is found on the ocean’s surface and, like land plants, contain chlorophyll that absorbs sunlight and converts it into energy.  Krill consume phytoplankton by scooping up particles from the water.  Their mouths can filter and trap these microscopic algae for consumption.

Copepods

Copepods are small crustaceans that live all over the oceans.  This creature can be freshwater or saltwater species.  There are over 240 species of copepods and the largest of these crustaceans are about 0.4 inches.  Krill usually focus on the smaller species of copepods found in the oceans.

Algae

Krill will feed on various types of algae that they find growing underneath the water.  Aquatic krill are quite fond of snow algae that grow in and on snow and ice in polar regions.  Krill can feed on these foods from the bottom of the ocean or they can rise to the surface to feed on algae.

Zooplankton

Some species of krill are mostly carnivores and mostly feed on zooplankton.  Zooplankton includes a huge variety of small ocean species such as snails, jellyfish, crustaceans, sea organisms, worms, sea cucumbers, mollusks, fish, fry, and many others.  Krill usually feed on zooplankton that floats about the water.  This food source is rich in protein and supplies krill of the needed energy.

Fish larvae

Larger krill will also catch and eat small fish larvae that they find drifting bout the ocean.  They will eat just about any type of fish larvae they can find that is small enough to fit into their small mouths.

Diet Variations

Different species of krill may prefer certain foods.  There are some species that are mostly herbivores and only feed on algae and phytoplankton.  Other species are carnivores and prefer to feed on zooplankton and copepods.  Other species like the Arctic krill are omnivore and feed on both plant and animal matter.   Some krill species are also cannibals and will eat each other.

How to Feed Krill

Krill are very small and only feed on small particles and sea animals they find drifting about the ocean.  In aquariums, these tiny animals are usually kept as feed for other animals and not as part of the observatory.  Those that do keep krill usually feed them by supplying these small animals with a variety of foods such as algae and zooplankton.

How Much Do Krill Eat?

Individual krill don’t eat much at all since they are quite small.  But swarms of krill can be quite huge and as such can eat surprisingly much.  Since krill consume microscopic food pieces it isn’t really possible to tell just how much each krill species will eat in a single sitting or per day.

How Often Do Krill Eat?

Krill will feed constantly throughout the day.  They are constantly filtering the ocean water for food in their search of microscopic food pieces.  They travel in swarms and feed as they proceed.

What do Baby Krill Eat?

Krill are crustaceans that are hatched from eggs.  One female krill can lay up to 10,000 eggs at a time and a female can lay eggs several times in the same season.  Their remarkable reproduction rate is exactly what ensures that these animals do not become extinct since they are an important food source to a huge variety of predators.

Hatchlings are called nauplii and are usually hatched around 3000 meters below sea level.  They consume the same foods as adult krill.  A krill can live up to 10 years but in oceans, they usually only live around 6 years.

Can Humans Eat Krill?

Humans can eat krill but this is not a common food source because they are so small.  They do however contain lots of protein and omega-3 fatty acids.  Instead of being served at restaurants, krill are often used as a dietary supplement in oil capsules.

In the 1960s up to the 1990s, the Soviet army was fed on krill because these foods offered lots of nutrition.  Krill was canned in small metal boxes and offered to troops to keep them energized and healthy.

What Are The Predators Of Krill?

Krill has a huge variety of predators including humans.  They are harvested to produce supplements and are sometimes used as a food source for armies.

In the ocean, these tiny animals are a very important food for a huge variety of sea animals.  Small to large animals feed on krill.  They are prey for fish, penguins, seals, and even huge baleen whales or blue whales.  One blue whale can eat up to 3,600kg of krill each day for about 120 days.