Euglena

Euglena gracilis

Euglena are small organisms in the Protist Kingdom. Euglena gracilis is just one of many species of Euglena. They do not have common names like birds or trees, so we have to refer to them by their scientific name.

Euglena are interesting because they are a sort of combination of plant and animal. They can make their own food like a plant, but they can also eat other things, like an animal. They can also swim and move. Scientists argued for years about which Kingdom to put them in, Animal or Plant? Right now they are in neither; most scientists put them in the Protist Kingdom with other microscopic organisms, such as amoeba and paramecium.

Copyright, LFS Cultures

Y. Tsukii

Euglena gracilis and other euglena are green because they eat green algae. They keep the algae inside their bodies and use it to make their own food. These green parts inside the Euglena's body are called chloroplasts.

A euglena's body is only one cell, so they are very small and you must use a microscope to see them. Sometimes, since they live in water, if there are millions of euglena together, they form a mat on the surface of a pond or marsh that you can see. It looks slimy, a lot like algae. Some people say it looks like "pea soup." It gets in swimming pools too, if they are not cleaned regularly. If you've ever seen water in a marsh that looks red, it's from many euglena. Some species have chemicals in them that make them red. Euglena gracilis is not one of those species.

Euglena gracilis has a long hair-like thing that stretches from its body (see top picture). You need a very powerful microscope to see it. This is called a flagellum, and the euglena uses it to swim. It also has a red eyespot. Euglena gracilis uses its eyespot to locate light. Without light, it cannot use its chloroplasts to make itself food.

In order for Euglena gracilis to make more Euglena gracilis it will complete a process called mitosis. That means it can split itself in half and become two Euglena gracilis. It can only do this if it is well-fed and if the temperature is right. Euglena gracilis can reproduce better in warm temperatures. The picture below shows an Euglena gracilis splitting into two. Can you see both eyespots?

Y. Tsukii

When Euglena gracilis doesn't have enough light to make its own food, it looks for other things to eat. Swimming around, it preys on other tiny organisms, such as amoeba and paramecium.

Predators of Euglena gracilis and other euglena include: baby fish, water fleas, mussels, and frogs and salamanders (tadpoles and larval stages).

One way that Euglena gracilis can get from one body of water to another is birds. Water birds, like ducks, geese, and herons get mud stuck to their feet. Euglena gracilis that are in the mud can get a free ride to a new pond, river, or marsh.

Additional Media

Description
Type
Credit
Euglena gracilis
Video
Rutgers University, Division of Life Sciences

Relationships in Nature:

PREY/FOOD
PREDATORS
SHELTER
OTHER

Green Algae

Creek Chub

Green Algae

Green Algae C

Amoeba

Tesselated Darter

Common Duckweed

Mallard C

Paramecium

Eastern Lamp Mussel

Yellow Pond Lily

Canada Goose C

Rotifer

Water Flea

Pickerelweed

Great Blue Heron C

Bullfrog

Common Cattail

Hydrilla EC

Wood Frog

Lizard's Tail

Greater Bladderwort SP

Eastern Newt

Tussock Sedge

Amoeba

Common Reed

Paramecium

Hydrilla

Crane Fly

Green Algae

Channel Catfish

Greater Bladderwort

Golden Shiner

Black Crappie

Northern Hog Sucker

Rotifer

Copepod

Scud

Predatory Nematode

Flatworm

Relationship to Humans:

Euglena gracilis, and other euglena, are harmless to people, but they are often signs that water is polluted, since they do well where there is a lot of green algae to eat. Green algae does well where there is a lot of nitrogen (comes from waste) in the water. If you don't clean your swimming pool, leaves and twigs get in the water and turn into waste. Then algae and euglena show up.

KINGDOM
Protist
PHYLUM
Euglenophyta
CLASS
Euglenophyceae
ORDER
Euglenales
FAMILY
Euglenidae
GENUS
Euglena
SPECIES
Euglena gracilis

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