Algae are plants that grow in water. They can be so small that you cannot see them with the naked eye. These are microalgae because you can only see them under a microscope. Macroalgae, on the other hand, can grow up to sixty meters long.
Algae can also be divided into seawater algae and freshwater algae. But there are also airborne algae on tree trunks or rocks and soil algae that live in the soil. Even snow algae in mountains or at the North Pole or at the South Pole.
Researchers estimate that there are around 400,000 different species of algae. However, only about 30,000 of them are known, i.e. not even every tenth. Algae are very distantly related to each other. What they all have in common is that they have a cell nucleus and that they can form their own food with sunlight. To do this, they produce oxygen.
But there is another special feature, namely the blue-green algae. Researchers used to think that these were also plants. Today we know, however, that it is bacteria. Strictly speaking, it is the class of cyanobacteria. Some species carry a substance that gives them their blue color. Hence the name. However, these bacteria can produce food and oxygen with the help of sunlight, just like plants. That’s why the wrong assignment was obvious. And because it has always been like that, blue-green algae are still often counted as algae, even though this is actually wrong.
Our word alga comes from the Latin language and means seaweed. We also sometimes use it for animals that aren’t actually algae, like blue-green algae: they look like algae, but they’re bacteria.
What is the use or harm of algae?
Every year, billions of tons of micro-algae grow in the world’s rivers and seas. They are important because they make up half of the oxygen in the air. They can do this at any time of the year, unlike our trees, which have no leaves in winter. They also store a lot of carbon dioxide and thus counteract climate change.
Algae that grow underwater form part of the plankton. Many animals live on it, for example, whales, sharks, crabs, mussels, but also sardines, flamingos, and many other animals. However, there are also toxic algae that can kill fish or injure people.
Humans also use algae. In Asia, they have long been a popular food. They are eaten raw in a salad or cooked as a vegetable. Algae contain many healthy substances such as minerals, fat or carbohydrates.
However, certain algae can also be used to obtain fibers for textiles, dyes for ink, fertilizers for agriculture, thickeners for food, medicines, and many other things. Algae can even filter toxic heavy metals from wastewater. Algae are therefore increasingly being cultivated by humans.
However, algae can also form dense carpets on the water. That takes away the desire to swim and many hotels on the beaches lose their customers and earn nothing more. The causes are fertilizer in the sea and the warming of seawater due to climate change. Some types of algae suddenly multiply very quickly. Others produce many more flowers, turning the water red.