Have you ever eaten algae? You probably have, although you might not have known it. Just what are algae, anyway?
The Mini Page talked with a scientist from the National Museum of Natural History, Smithsonian Institution, to learn more about algae and their importance to humans and animals.

What are algae?

An alga (AL-guh) is a plant-like organism. Most live in groups, so we usually use the plural, algae (AL-jee).
Algae are simple organisms. Sometimes larger algae look like plants, but they don’t have specialized parts, such as leaves or roots.
There are thousands of different types. Algae can be single cells so small that hundreds could fit on the period at the end of this sentence. Or they can be large, many-celled organisms.
Phytoplankton (FIE-toe-PLANK-tun) are a type of algae that live in bodies of water. They are usually made of only one cell. (Zooplankton, or single-celled animals, are not algae.)


Most algae live where it is very moist, in the sea or in bodies of fresh water. They also live in soil and snow. One type of algae lives by using the morning dew in the desert.

Feasting on sunlight

Like plants, most algae use sunlight to turn carbon dioxide gas and water into food. When organisms create their food out of light, it is called photosynthesis (foe-toe-SIN-the-sis).
Algae and plants take in carbon dioxide and give off oxygen. Luckily for people and animals, oxygen is the waste product of photosynthesis. We couldn’t live without the oxygen produced by algae.
Algae are often organized by their colors, which are usually shades of green, red or brown. Different colors have different ways of using photosynthesis. Experts believe each color probably developed, or evolved, from a different organism.