Phytoplankton are tiny plants that live in water, both fresh and salty. Their name comes from Greek words meaning “plant” and “drifter,” because they float around in the water. Even though they are so small you can’t see them without a microscope, they are super important for keeping our planet healthy and helping life to grow and change.
There are three main types of phytoplankton: bacteria, protists, and single-celled plants. Some of the most common ones are cyanobacteria, diatoms, green algae, and coccolithophores. Even though they are tiny, they are a big part of the ocean’s food chain and are important for life on Earth.
Phytoplankton are like the starting point of the food chain in the ocean. They are eaten by small animals like zooplankton, which are then eaten by bigger animals like fish and even whales. When plants and animals die, bacteria, fungi, and worms break them down, helping to recycle nutrients in the water.
Just like plants on land, phytoplankton have chlorophyll, which helps them use sunlight to make energy through a process called photosynthesis. During this process, they take in carbon dioxide and release oxygen. Amazingly, phytoplankton produce about half of the oxygen we breathe, which is as much as all the trees and plants on land combined!
Phytoplankton have been around for a very long time, about 2.5 billion years! Back then, the Earth looked very different, with green oceans and an orange sky. There wasn’t much oxygen, so complex life couldn’t survive. But about 800 million years ago, some phytoplankton started producing a lot of oxygen, changing the atmosphere and making it possible for more complex life to develop in the oceans and on land.
Today, if the number of phytoplankton goes down, it can affect many things, like the variety of life in the ocean, the fish we eat, and even the climate. This shows how important these tiny plants are for keeping everything in balance.
In short, phytoplankton are super important for life on Earth. They help make food, produce oxygen, and have played a big role in the history of life on our planet. It’s important to understand how amazing these tiny plants are and why we need to protect them.
Phytoplankton Observation Jar: Create your own mini ocean ecosystem! Fill a clear jar with water and add a few drops of green food coloring to represent phytoplankton. Place the jar in a sunny spot and observe how the light affects the “phytoplankton.” Discuss with your friends or family how real phytoplankton use sunlight to produce oxygen through photosynthesis. Can you see any changes in your jar over a few days?
Food Chain Role Play: Gather a group of friends or family members and assign each person a role in the ocean food chain, such as phytoplankton, zooplankton, small fish, and large fish. Act out how energy and nutrients move through the food chain, starting with the phytoplankton. Discuss how each role is important and what might happen if one part of the chain is missing.
Oxygen Experiment: Did you know that phytoplankton produce about half of the oxygen we breathe? Try this experiment to understand how important oxygen is. Take two small jars and place a candle in each. Light the candles and cover one jar with a lid. Observe what happens to the candle in the covered jar compared to the open one. Discuss why oxygen is important for life and how phytoplankton contribute to the oxygen we breathe.
