What is phytoplankton?

Phytoplankton are tiny water plants that float in the ocean and help make the water green.

Imagine you're swimming in a big, clear pool, and there are millions of little green plants floating around you, so small, you can’t see them unless you look really closely. These tiny plants are called phytoplankton. Just like how plants on land use sunlight to make food, phytoplankton use sunlight too, but they do it in the water.

Phytoplankton are like the superstars of the ocean, because lots of other sea creatures depend on them. Little fish eat them, and those little fish get eaten by bigger fish, which then get eaten by whales or dolphins. It’s kind of like a big food chain that starts with phytoplankton.

You can find phytoplankton in lakes, rivers, and even in the ocean, wherever there's water and sunlight. Sometimes, when there are lots of them, the water looks green or blue-green, almost like it’s alive!