WHAT ARE PHYTOPLANKTON AND ZOOPLANKTON?

Phytoplankton and zooplankton are the microscopic foundation of the ocean food chain. They are tiny organisms that drift with currents, but they are very different from each other.

🌿 Phytoplankton

Phytoplankton are tiny plant-like organisms that make their own food through photosynthesis.

They use:

Sunlight + carbon dioxide + water + nutrients → energy (food) + oxygen

Examples include:

• Diatoms
• Dinoflagellates
• Cyanobacteria

They are extremely important because they produce a significant proportion of the world's oxygen and form the base of marine food webs.

🦐 Zooplankton

Zooplankton are tiny animals—or animal-like organisms—that cannot make their own food.

They feed on phytoplankton and sometimes on other zooplankton.

Examples include:

• Copepods
• Krill
• Jellyfish larvae
• Fish larvae

A simplified food chain is:

☀️ Sunlight
↓
🌿 Phytoplankton
↓
🦐 Zooplankton / Krill
↓
🐟 Small fish
↓
🐟 Larger fish
↓
🐋 Marine animals / Humans

How this relates to omega-3

This is particularly interesting in relation to your earlier questions about EPA and DHA.

Phytoplankton are important primary producers of omega-3 fatty acids, particularly DHA and EPA. Zooplankton consume phytoplankton and acquire these fatty acids. Small fish then eat zooplankton, and larger fish eat the smaller fish.

So one simplified pathway is:

Phytoplankton → Zooplankton/Krill → Small fish → Larger fish → Humans

This is one reason fatty fish such as salmon, sardines, mackerel and herring contain substantial amounts of EPA and DHA.

An interesting point

Fish don't necessarily create all their EPA and DHA from scratch. Marine algae and phytoplankton are an important original source of these long-chain omega-3 fatty acids.

This is also why algal oil can contain DHA and/or EPA and can provide omega-3 without obtaining it from fish.

So, in very simple terms:

Phytoplankton = the "plants" of the ocean 🌿
Zooplankton = the "tiny animals" that eat them 🦐

And together they form the beginning of much of the marine food chain.