A group of krill is called a swarm.
Unlike a lot of collective nouns on this site, “swarm” isn’t a stretch or a borrowed word applied for the sake of wordplay, it’s a plain, accurate description of what krill actually do. These small, shrimp-like crustaceans gather by the billions in some of the largest aggregations of any animal on the planet, and the word for the group reflects that directly.
What Is a Group of Krill Called?
The term used for a group of krill is a swarm of krill. It’s a straightforward, biologically accurate label, krill genuinely swarm, and their swarms are among the largest coordinated animal groupings in the ocean.
Where Did the Name Come From?
“Swarm” is an old, general-purpose English word used for centuries to describe large, densely packed groups of small animals moving together, most familiarly bees and other insects. Its application to krill isn’t tied to any specific historical coinage or hunting tradition, krill weren’t quarry in the old “terms of venery” sense cataloged in works like the Book of Saint Albans (1486). It’s simply the same general word for a dense, moving mass of small creatures, applied to krill because it fits so well.
In this case, the term earns its place honestly: krill really do form the kind of dense, chaotic mass that “swarm” is meant to describe, at a scale that’s genuinely hard to picture.
Krill Facts
- Habitat: Krill live in oceans worldwide, with Antarctic krill concentrated in the cold waters of the Southern Ocean, where they form the base of the food web.
- Social behavior: Krill are highly social by necessity, forming dense swarms that can stretch for kilometers and reach densities of tens of thousands of individuals per cubic meter; some superswarms have been estimated to weigh millions of tons. This makes “swarm” one of the most biologically accurate collective nouns on this entire site.
- Diet: Krill are filter feeders, primarily grazing on phytoplankton, using specialized legs to comb tiny algae out of the water.
- Lifespan: Antarctic krill typically live around 5-10 years, which is unusually long for such a small crustacean.
- Massive migration: Krill perform one of the ocean’s largest daily animal migrations, rising toward the surface to feed at night and sinking back into deeper water during the day, all in sync as a swarm.
- Bioluminescent: Many krill species can produce their own light, likely used for communication or camouflage against predators below them.
Example Sentences
- A swarm of krill lit up the dark water with a faint blue glow.
- The whale lunged straight through a swarm of krill near the surface.
Other Names for a Group of Krill
Explore the collective noun for krill in more depth:
Frequently Asked Questions
What is a group of krill called?
A group of krill is called a swarm, an accurate description of how krill actually gather in the wild.
Is “swarm” biologically accurate for krill?
Yes. Krill genuinely form dense swarms containing billions of individuals, among the largest animal aggregations in the ocean, so the term describes real behavior rather than being a borrowed or whimsical word.
How big can a krill swarm get?
Krill swarms can stretch for kilometers and reach densities of tens of thousands of individuals per cubic meter. Some documented superswarms have been estimated to weigh millions of tons.
What do krill eat?
Krill are filter feeders that primarily eat phytoplankton, tiny algae they comb out of the water using specialized legs.
How long do krill live?
Antarctic krill typically live around 5-10 years, which is unusually long for such a small crustacean.
Related: Collective Nouns for Crustaceans