Algae, members of a group of predominantly aquatic photosynthetic organisms of the kingdom Protista.

This group of photosynthesising aquatic organisms come in many shapes and sizes and you'll probably recognise them from kelp and seaweed, but there is a lot more to them than that.

Here are a few vital algae facts to help you understand one of the world's most important organisms.

1.
Algae, like plants, are photosynthetic organisms.
They are common on "slimy" rocks in streams and as green sheens on pools and ponds.

2.
The word algae is the plural form of "alga," which comes from Latin and means "seaweed."
Similarly, the study of algae is called phycology, after the Greek word "phykos," which also means seaweed.

3.
Once classified as plants, algae are now known to be a grab bag of species defined as much by what they are not as by what they are. They're not a true taxonomic group, like cats or fungi; they have no one common ancestor.

4.
Algae are part of the kingdom Protista, which includes mostly single-celled organisms that are neither plants nor animals.

5.
The different types of algae, such as red, green, and brown, are classified based on their chlorophyll pigments.

6.
Algae is one of the many diverse organisms that are included under the umbrella term "plankton," along with bacteria, protozoa, and even microscopic fungi.

7.
Algae play a crucial role in aquatic ecosystems as primary producers, forming the base of the food chain.

8.
Through the process of photosynthesis, algae produce as much as 30 to 50 percent of the Earth's oxygen levels.

9.
According to fossil records, oxygen-producing green algae is at least 1 billion years old.

10.
Algae's role in climate change mitigation is studied for their ability to absorb carbon dioxide from the atmosphere.

11.
Algae play a crucial role in lichen, a symbiotic organism composed of algae and fungi.
The algae provide photosynthetic capabilities, while the fungi offer structure and protection.

12.
Excess nitrogen and phosphorus cause an overgrowth of algae in a short period of time, also called algae blooms. Often due to runoff from agriculture and urban areas.
Algae blooms, often visible as green, blue, or red layers on water, can drastically affect water quality and aquatic life.
Some harmful algal blooms release toxins that can endanger human health and marine life.

13.
Some species of algae can survive in harsh environments, thanks to hardy genes they stole from bacteria.

14.
Algae's ability to grow quickly and in many types of water bodies makes them a potential source of biofuel.

15.
Certain algae play a role in the wastewater treatment process by removing harmful chemicals, such as phosphorus and nitrogen, and by absorbing nutrients.

16.
Algae as a food have been explored for different applications as in production of single cell proteins, pigments, bioactive substances, pharmaceuticals and cosmetics.

17.
Blue-green algae, also known as cyanobacteria, are not true algae but bacteria that photosynthesize like algae.

18.
Red algae are better at absorbing blue light than other colors of algae.
Red algae are red because of the presence of the pigment phycoerythrin ; this pigment reflects red light and absorbs blue light. Because blue light penetrates water to a greater depth than light of longer wavelengths, these pigments allow red algae to photosynthesize and live at somewhat greater depths than most other "algae".

19.
Brown algae include giant kelp, which can grow up to 215 feet (65 meters) long, making them some of the largest algae.

20.
Algae are an important source of food for various aquatic organisms, including fish and shellfish.

21.
Algae are vital in studying plant-like organisms, helping scientists understand more about photosynthetic life forms.

22.
Coral reefs rely on a symbiotic relationship with algae, which provide the corals with food through photosynthesis.
In return, the reefs provide much-needed shelter to the algae.

23.
Algal oil, made from algae, is a great vegan alternative to fish oil, as it contains many omega-3 fatty acids.

24.
Fish contain high amounts of essential omega-3 fatty acids because they eat microalgae.
Omega-3 fatty acids are healthy fats found in fish that support your heart health and overall well-being.
Fish high in omega-3 include salmon and herring.

25.
Certain types of "seaweed" (the common name for countless species of marine plants and algae) have been consumed globally for centuries and are a staple of East Asian and Pacific cuisines.

26.
Livestock feed often includes algae, which provide high levels of proteins and nutrients beneficial for animal health.

27.
Understanding algae is essential for managing and conserving aquatic life and health, given their impact on ecosystems.

28.
World Algae Day is celebrated annually on October 12 and showcases how essential algae is to our planet and its potential uses in creating sustainable food, fuel, and medicine.

29.
It's believed by many scientists that without algae, there would be no life on Earth.

30.
Scientists also believe that algae may be the reason we ever evolved in the first place, as oxygen-producing algae created our oxygen-rich atmosphere.

Sources
Britannica - Algae / Wikipedia - Cyanobacteria / Byju's / Britannica - Macrocystis / Wikipedia - Ice Algae / Global Institute of Sustainability and Innovation / Britannica - Protist / Princeton University / U.S. National Science Foundation / Rutgers / Wikipedia - Algal Bloom / WebMD / National Library of Medicine / Wikipedia - Nori / Nutri News / Whitfords / Wikipedia - Plankton / Live Science / Study.com / Science Direct / Algaeo.com / The Fact Site