When travelers imagine Antarctica, they often picture towering glaciers, vast icebergs, and iconic wildlife like penguins and whales.
But beneath this dramatic landscape lies a far less visible – yet absolutely essential – component of the ecosystem: krill.
For those planning an Antarctic expedition, understanding the role of krill offers valuable insight into why wildlife encounters vary by region and season, and how the entire Southern Ocean ecosystem functions.
In many ways, these tiny crustaceans shape the very experiences you’ll have on your journey.
What are krill and why do they matter?
The Southern Ocean is vitally important in the entire Antarctic food web, and at the base of this web are two tiny players: phytoplankton and the krill that eat it.
Krill are 85 or so species of small shrimp-like crustaceans (order Eucarida), the most abundant being the Antarctic krill (Euphausia superba), which can reach 10,000 – 30,000 individual animals per cubic meter.
Despite their modest size (around the length of your little finger), Krill are thought to be one of the most successful animal species on the planet. Their ecological role is essential to Antarctica for one key fact: krill are the foundation of the Antarctic food web.
Almost all Antarctic consumers rely directly or indirectly on them as a food source. It is amazing to think that the largest animal on the planet, the blue whale, feeds exclusively on krill!
The populations of krill and all other Antarctic animals are crucially linked.
So how does this intricate food web work?
To understand Antarctica’s wildlife, it helps to break down the food web into its core components:
1. Phytoplankton: the starting point
During the austral summer, the Southern Ocean becomes incredibly productive. With extended daylight hours and nutrient-rich waters, phytoplankton—microscopic marine plants—rapidly bloom. These organisms can double their population in a matter of hours under ideal conditions.
2. Krill: the key link
Krill feed continuously on phytoplankton, converting plant energy into a form that larger animals can consume. Their ability to form dense swarms makes them an efficient and reliable food source.
3. Wildlife: from penguins to whales
A wide range of Antarctic species rely on krill, including:
- Penguins (such as gentoo, chinstrap, and Adélie)
- Seals (like crabeater and fur seals)
- Baleen whales, including the blue whale, which feeds almost exclusively on krill
Higher up the chain, predators like leopard seals and orcas prey on penguins and seals, indirectly linking back to krill as well.
For travelers, this interconnected system explains why areas rich in krill often deliver the most memorable wildlife sightings.
Why krill influence your Antarctic experience
If you’re comparing Antarctic cruises or itineraries, krill distribution is an often -overlooked factor that directly impacts what you’ll see.
Wildlife hotspots depend on krill
Regions with high krill concentrations attract feeding whales, active penguin colonies, and large seal populations. Expedition leaders often adjust routes based on ice conditions and known feeding areas to maximize wildlife encounters.
Timing matters
Krill populations fluctuate throughout the season, influencing animal behavior:
- Early season (November–December): Wildlife is focused on breeding; feeding activity is present but less concentrated.
- Mid to late season (January–March): Increased krill availability supports more intense feeding, often leading to dramatic whale activity.
Ice conditions play a role
Sea ice affects both phytoplankton growth and krill distribution. As ice melts, it releases nutrients that fuel the entire food chain—another reason why each departure can offer a slightly different experience.
For travelers in the planning stage, this highlights the value of choosing an experienced operator who understands how to interpret these environmental patterns.
Krill At-A-Glance
- Actual size: your pinky finger (about 2.5 inches)
- Color: transparent with red shells
- Population: ~500 million in the Southern Ocean
- Lifespan: Up to 10 years (average: 6)
- It is being debated that Krill oil is better for you than Fish oil!
Krill may be small, but their impact on Antarctica is immense. They are the invisible engine driving the entire ecosystem – from microscopic plant life to the largest animals on Earth.
For travelers, this means that every penguin colony, every whale sighting, and every unforgettable wildlife moment is ultimately connected back to these tiny crustaceans.
By understanding how the Antarctic food web works, you’re better equipped to choose the right time and place for your expedition – and to fully appreciate the complexity of the environment you’re about to explore.
In Antarctica, even the smallest details can shape the biggest experiences.
