What is a synonym for krill?

There isn't really a perfect synonym for "krill" in the way that "dog" and "canine" are synonyms. Krill are a specific type of small crustacean, and while there are other small crustaceans, they aren't technically krill.

Here are some terms that might be used in a similar context, depending on the situation:

* Plankton: This is a broader term that encompasses all small organisms that drift in the water. Krill are a type of zooplankton.

* Crustaceans: This is a larger category of animals that includes krill, crabs, lobsters, and shrimp.

* Euphausiids: This is the scientific order that krill belong to.

Ultimately, the best way to replace "krill" depends on the specific context and the intended meaning.