Algae

Have you ever seen a pond that looked like it was painted with thick green swirls, or felt a slippery, slimy coating on a rock by the ocean? That was me. I can be as tiny as a speck of dust floating in the water, so small you need a special glass to see me, or I can grow as big and majestic as a forest of kelp, with long ribbons swaying under the waves. I live almost everywhere there is water, from the coldest arctic seas to bubbling hot springs on land. I come in many colors, too—bright green, deep red, murky brown, and even a special blue-green. But my most important job is something you do every second of every day without even thinking about it: breathing. I am a master of turning sunlight into energy, and while I do it, I give the world a special gift. Like a tiny chef, I soak up the sunshine, drink in some water, and breathe in the air that you breathe out. Then, I cook up a treat for the whole planet: fresh, clean oxygen. I have been puffing out the air you need for billions of years, long before the first flowers bloomed or the first animals walked on land. You have many names for me, from seaweed to phytoplankton, but you can call me by my family name: Algae.

My story is one of the oldest stories on Earth. I was here for billions of years before the dinosaurs even existed. Can you imagine that? My earliest ancestors, a type of blue-green algae you call cyanobacteria, first appeared around 3.5 billion years ago. Back then, the air on Earth was very different and not friendly for creatures like you. It was thick with gases that you couldn’t breathe. So, I got to work. Starting around 2.4 billion years ago, I began releasing huge amounts of oxygen into the atmosphere during an event scientists call the Great Oxidation Event. It was a very, very long process, but I changed everything, making it possible for all kinds of complex life, including your own ancestors, to evolve. People discovered my usefulness a long time ago, too. As far back as 600 BCE, people in China considered some of my seaweed relatives a special and delicious food fit for an emperor. Later, in the 14th century, the Aztec people in what is now Mexico harvested my cousin, Spirulina, from lakes. They would dry it into little cakes that were packed with protein. For centuries, though, my tiniest forms remained a secret. That all changed in the year 1674, when a curious man from the Netherlands named Antonie van Leeuwenhoek peered through his amazing new invention, the microscope. In a single drop of pond water, he saw my microscopic family members for the very first time, swimming and spiraling about. He called them “animalcules,” or little animals. He opened up a whole new, invisible world—my world.

Today, you can find me almost everywhere, and not just in the water. I am a secret ingredient in many things you use every day. Do you like your ice cream to be smooth and creamy? A substance from me called carrageenan helps make it that way. Have you ever eaten sushi? The dark, paper-like wrapper around the rice and fish is one of my relatives, a red alga called nori. Scientists even use a jelly made from me, called agar, to grow and study tiny life forms in their labs. But I'm also helping to solve some of the world's biggest problems. Scientists are learning how to turn me into biofuel to power cars and planes, which is much cleaner for the air than gasoline. I can be used to make bioplastics that break down naturally instead of cluttering up the planet. And I am still doing my most important job: breathing in the carbon dioxide that is making our world too warm. I may be simple, but I am powerful. I helped create the world you live in, and I’m still working hard to build a cleaner, greener future for everyone.