Green Algae

Pediastrum boryanum

Y. Tsukii

Pediastrum boryanum is one of many species of tiny plants that are called "green algae." Actually, any species in the Chlorophyta Division (phylum) is called green algae. Green Algae come in many different shapes and sizes. Pediastrum boryanum is the scientific name of one green algae species.

To see one Pediastrum boryanum you will need a microscope. If many Pediastrum boryanum are together, probably with other species of algae as well, they will look like green slime in the water.

Peter v. Sengbusch

Y. Tsukii

What you see in the pictures are actually colonies of Pediastrum boryanum. Colonies are circular, star-like shapes, usually made up of eight, sixteen, or thirty-two individual Pediastrum boryanum. Smaller colonies with two or four Pediastrum boryanum don't stay that way long, because they grow fast. Sometimes there can be more Pediastrum boryanum in a colony, but not very often.

Pediastrum boryanum colonies are green and float around in ponds, marshes, lakes, pools, and rivers.

The reason some colonies look greener in some of the pictures than others, is because some of the colonies are in the process of making more Pediastrum boryanum. The ones that are not fully made yet, look like they're not "filled out."

Copyright, John Kinross

Each prickly little shape in the colony is an individual organism. Pediastrum boryanum have only one cell, but just like larger plants, such as trees, they can make oxygen. This is important for animals, and for us, since water must have oxygen in it in order to stay water. Underwater animals with gills, such as fish and tadpoles, need to breathe oxygen through water. Other animals, including people, need to drink water to survive.

The way Pediastrum boryanum make more Pediastrum boryanum is when, one at a time, each Pediastrum boryanum cell in the colony releases tiny things called zoospores. Zoospores leave the colony and make a new colony. Each Pediastrum boryanum in a colony releases zoospores at different times, so that a colony is almost always making new colonies.

How fast algae grows depends on how much light it gets, the temperature, and amounts of nutrients in the water. Like other plants, algae can make their own food. To do this, they must have light to complete the process called photosynthesis. Algae can grow faster in warmer temperatures. Even though Pediastrum boryanum lives in water year-round, it does not grow nearly as fast in Winter as it does in Summer. Different bodies of water have different nutrients in them. Like all plants, algae needs to absorb nitrogen. One thing that provides nitrogen is animal waste (poop). Therefore, algae helps all organisms by taking in waste (poop, dead animal and plant matter) from the water, providing oxygen, and by being a food source for animals.

One way that Pediastrum boryanum and other green algae are able to spread from one body of water to another is birds. When ducks, geese, herons, or other water birds fly to new areas, they carry mud on their feet. Inside the wet mud, algae can survive until it lands in a new body of water.

Animals that eat green algae include frogs and salamanders (tadpole and larval stages), crayfish, aquatic insects, snails, some fish, water fleas, mussels, amoebas, paramecium, water bears, and many others.

Pediastrum boryanum cannot move on its own. It stays with its colony and floats with currents in the water. When many colonies in the same area stick together, they provide cover for fish, aquatic insects, and other animals.

Pediastrum boryanum helps controls Zebra Mussels. Zebra Mussels were introduced from another country and have become a terrible pest. They are smaller mussels which attach and cover larger native mussels, making it difficult for them to move and eat. Zebra Mussels often kill our native mussels, such as the Eastern Lamp Mussel, this way. Pediastrum boryanum colonies clog the filters of Zebra Mussels so they can't eat. Therefore, Pediastrum boryanum helps our native mussels and our aquatic habitats. Zebra mussels have not shown up in Virgina yet, but they are a huge problem in other states and scientists believe it's only a matter of time before we have them too.

Additional Media

Images of Other Species of Green Algae
Link to Ohio University Algae Page
Ohio University

Relationships in Nature:

Animals Using as Food Source

Animals Using as Shelter

Associations With Other Plants


Golden Shiner

Creek Chub

Yellow Pond Lily

Mallard D

Channel Catfish

Tesselated Darter

Common Duckweed

Canada Goose D

Water Flea

Golden Shiner


Great Bue Heron D


Crane Fly

Common Cattail

Euglena C


Eastern Dobsonfly

Tussock Sedge

Hydrilla EC

Water Bear

Green Darner

Lizard's Tail

Spotted Salamander C


Large Diving Beetle

Common Reed

Crane Fly



Wood Frog

Southern Leopard Frog

Greater Bladderwort


American Toad

Arrow Arum

Eastern Lamp Mussel

Eastern Newt

Stagnant Pond Snail




Snow Flea

Water Flea

Wood Duck


Southern Leopard Frog

Snow Flea

Common Carp

Spotted Salamander


Black Crappie

Eastern Mosquitofish

Ebony Jewelwing

Northern Caddis Fly

Northern Caddis Fly

Relationship to Humans:

As mentioned above, Pediastrum boryanum and other green algae are important because they convert nitrogen from waste into a form other animals can use. Large amounts of algae in a body of water is also a sign that the water may be polluted. Since green algae does so well in water with lots of waste, there is a good chance that water is polluted when you see a lot of algae. Scientists use this information to identify polluted waters and to try to figure out ways to clean them up.


Pediastrum boryanum


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