Krill vs. Plankton — What's the Difference?
By Urooj Arif & Fiza Rafique — Updated on May 15, 2024
Krill are small crustaceans forming a significant part of marine diets, while plankton refers to a diverse group of tiny organisms drifting in water, including both plants (phytoplankton) and animals (zooplankton).
Difference Between Krill and Plankton
Table of Contents
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Key Differences
Krill are small, shrimp-like crustaceans found in oceanic waters. They are a crucial part of the marine food web, serving as a primary food source for many larger marine animals, such as whales, seals, and fish. On the other hand, plankton is a broader term that encompasses all microscopic organisms that float in aquatic environments. This includes both phytoplankton, which are plant-like and perform photosynthesis, and zooplankton, which are animal-like and include organisms such as krill.
Krill primarily feed on phytoplankton and other small zooplankton. This makes them an integral link in the ocean's food chain by transferring energy from the primary producers (phytoplankton) to larger predators. Plankton, however, includes a wide range of organisms from different taxonomic groups, contributing to various ecological roles, from primary production to being prey for other marine creatures.
Krill are relatively larger compared to many types of plankton, especially phytoplankton, which are often microscopic. Plankton size can vary widely, from tiny bacteria to larger zooplankton like jellyfish larvae. This diversity means that plankton can inhabit various niches and adapt to different environmental conditions, whereas krill are more specific in their habitat requirements, typically found in cold ocean waters.
Krill contribute significantly to marine biomass, especially in polar regions where they are most abundant. Their swarming behavior can form large, dense groups that are crucial for the diet of many marine predators. Plankton, while also contributing to biomass, do so across a broader range of ecosystems and trophic levels, influencing nutrient cycles and supporting marine life globally.
Comparison Chart
Type
Small crustaceans
Microscopic organisms (plants and animals)
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Role in Food Web
Primary food source for larger marine animals
Includes primary producers and various trophic levels
Size
Larger, visible to the naked eye
Ranges from microscopic to larger forms
Habitat
Cold ocean waters, especially polar regions
Aquatic environments globally
Ecological Contribution
Major biomass in polar regions
Influences nutrient cycles, supports marine life
Compare with Definitions
Krill
Primary food source for whales and seals.
The whale's diet consists mainly of krill.
Plankton
Microscopic organisms drifting in water.
Plankton are the foundation of the aquatic food web.
Krill
Small crustacean found in ocean waters.
Krill are essential for the diet of many marine species.
Plankton
Includes phytoplankton and zooplankton.
Phytoplankton and zooplankton are both types of plankton.
Krill
Known for forming large swarms.
Krill swarms can be seen from space due to their density.
Plankton
Primary producers in aquatic environments.
Phytoplankton perform photosynthesis, producing oxygen.
Krill
Play a crucial role in the marine ecosystem.
Krill help transfer energy up the food chain.
Plankton
Vital for marine nutrient cycles.
Plankton contribute to the carbon cycle in the ocean.
Krill
Feed on phytoplankton.
Krill consume large amounts of phytoplankton daily.
Plankton
Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters.
Krill
Krill are small crustaceans of the order Euphausiacea, and are found in all the world's oceans. The name "krill" comes from the Norwegian word krill, meaning "small fry of fish", which is also often attributed to species of fish.
Plankton
The small or microscopic organisms that drift or swim weakly in a body of water, including bacteria, diatoms, jellyfish, and various larvae. Plankton is an important food source for fish and other larger organisms.
Krill
The collection of small marine crustaceans of the order Euphausiacea that are the principal food of baleen whales.
Plankton
(uncountable) Organisms, especially small and microscopic ones, that drift in water.
Krill
Any of several small marine crustacean species of plankton in the order Euphausiacea in the class Malacostraca.
Plankton
(uncountable) A plankter, any single organism that drifts in water.
Krill
Shrimp-like planktonic crustaceans; major source of food for e.g. baleen whales
Plankton
All the animals and plants, taken collectively, which live at or near the surface of salt or fresh waters.
Plankton
The aggregate of small plant and animal organisms that float or drift in great numbers in fresh or salt water
Plankton
Diverse in size and type.
Plankton range from tiny bacteria to larger jellyfish larvae.
Common Curiosities
What is plankton?
Plankton refers to a diverse group of microscopic organisms that drift in aquatic environments.
Are krill a type of plankton?
Yes, krill are considered zooplankton because they are small animals that drift in the ocean.
What is the difference between phytoplankton and zooplankton?
Phytoplankton are plant-like and perform photosynthesis, while zooplankton are animal-like and include organisms like krill.
What are krill?
Krill are small, shrimp-like crustaceans that are a vital food source for many marine animals.
What do krill eat?
Krill primarily feed on phytoplankton and other small zooplankton.
Why are krill important to the marine ecosystem?
Krill are crucial for transferring energy from primary producers to larger predators in the marine food web.
How do krill contribute to marine biomass?
Krill form large swarms that contribute significantly to the biomass in their habitats, especially in polar regions.
What roles do plankton play in the ocean?
Plankton contribute to nutrient cycles, primary production, and serve as a food source for many marine organisms.
Do all plankton perform photosynthesis?
No, only phytoplankton perform photosynthesis; zooplankton, including krill, do not.
Do krill live in warm waters?
Krill are typically found in colder ocean waters, though some species can be found in warmer regions.
How does plankton diversity affect marine ecosystems?
The diversity of plankton supports various trophic levels and ecological processes, making them essential for healthy marine ecosystems.
Where are krill most commonly found?
Krill are most abundant in cold ocean waters, particularly in polar regions.
How big are krill compared to other plankton?
Krill are relatively larger and visible to the naked eye, while many plankton are microscopic.
Can plankton be seen without a microscope?
Some larger plankton can be seen without a microscope, but many are microscopic.
What is the primary habitat of plankton?
Plankton inhabit aquatic environments globally, from oceans to freshwater bodies.
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Written by
Urooj ArifUrooj is a skilled content writer at Ask Difference, known for her exceptional ability to simplify complex topics into engaging and informative content. With a passion for research and a flair for clear, concise writing, she consistently delivers articles that resonate with our diverse audience.
Co-written by
Fiza RafiqueFiza Rafique is a skilled content writer at AskDifference.com, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.
