Euglena

By Katie Nelson

What do Euglena look like?

• Usually an oval or round shape• Has a pigmented organelle called an “eyespot”

near the flagellum • Some have chloroplasts and mitochondria, some

just one or the other• Paramylon granules• Two flagella (one does not protrude the

membrane, so it is not as visible)• No cell wall, but rigid pellicle• Nucleus and nucleolus• Contractile vacuole to control water levels inside

the euglena

Eyespot

• Detects light to help euglena find a source of energy

• A light shield allows only a certain amount of light to hit the eyespot, which helps the euglena get the appropriate amount it needs

• Since the light shield and eyespot are only located in one area, the direction in which the source is will be able to be detected

• The euglena then moves the light source of appropriate intensity

Paramylon

• A unique glucose polymer in which euglenas store surplus food

• Spread throughout the cytoplasm

Pellicle

• Rigid, but flexible enough to allow the euglena to change shape, which helps it to ingest organic materials

• Also allows it to move like an inchworm

Mixotrophic

• Can be autotrophic or heterotrophic if have both chloroplasts and mitochondria

• If there is no light source, the euglena will act heterotrophic and absorb organic materials from its surroundings

A Good Defense

• When conditions are not stable enough for the euglena to survive, such as the temperature rising or lowering too much, it will form a protective covering called a cyst around its body until conditions improve.

Flagella are not its only way of travel…….

• A specific type of euglena, the Euglena gracilis, can move from one body of fresh water to another when birds that feed in the fresh water get mud stuck on their feet. Then the euglena gracilis in the mud can move to whatever fresh water source the bird flies to.

A Closer Look

Another Closer Look

Species of Euglena

Eutrophication• You can tell if a body of water is

polluted when euglenas are thriving in that source. Euglenas love to feed on green algae, which feed on nitrogen, a type of waste. The primary producers who ingest these nutrients create toxins harmful to plants and animals, as well as decreases, sometimes detrimental decreases, in dissolved oxygen. When these levels become hypoxic, or detrimental, plants, fish, and marine mammals do not get the oxygen they need. Therefore, biodiversity is decreased. In serious cases, conditions may become anaerobic, in which case Clostridium botulinumor may grow, which produce toxins deadly to birds and mammals. Birds and mammals also dependent on food sources in fresh or stagnant water are at risk as well.

Bibliography• Campbell, Neil A., Jane B. Reece, and Lawrence G.

Mitchell. “Biology: Fifth Edition.” California: Benjamin/Cumings, an imprint of Addison Wesley Longman, Inc., 1999c.

• “Euglena: Euglena gracilis.” Fairfax County Public Schools. 25, Jan. 2009 http://www.fcps.edu/islandcreekes/ecology/euglena.htm

• SilicaSecchiDisk.conncoll.edu, 27, Jan. 2009 http://silicasecchidisk.conncoll.edu/LucidKeys/Carolina_Key/html/Euglena_Main.html