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General Characteristics of Euglena | Labeled Diagram

In this article, we will learn the general characteristics of Euglena and its labeled diagram.

Euglena is a diverse group of single-celled organisms that belong to the phylum Euglenophyta. They are found in a variety of freshwater environments, including ponds, lakes, rivers, streams, etc.

Systematic Position of Euglena

Domain: Eukaryota
Kingdom: Protista
Phylum: Euglenozoa
Subphylum: Sarcomastigophora
Class: Euglenoidea
Order: Euglenida
Family: Euglenaceae
Genus: Euglena

Habit and Habitat of Euglena

  • They are found in a variety of freshwater environments, such as ponds, lakes, and rivers.
  • They are able to survive in a wide range of conditions, from acid bogs to saline lakes.
  • They can also be found in both clear and turbid water.
  • They are typically found in environments with moderate to high levels of light, as they are photosynthetic.
  • They are also found in environments with adequate levels of nutrients, such as dissolved inorganic compounds, and organic compounds.
  • They are known for their movement in response to light, a behavior known as phototaxis.
  • They move towards light using their flagellum.
  • They are also capable of heterotrophic nutrition which means they can absorb nutrients from their environment.
  • They are also known to use both photosynthesis and heterotrophic nutrition as a source of energy, making them versatile organisms.

Labeled Diagram of Euglena

structure and diagram of Euglena

Fig: Diagram of Euglena

General Characteristics of Euglena

Here are the most important general characters of Euglena are given below.

  1. Cell structure: They are single-celled organisms with a single flagellum used for movement. They also have a pellicle, a flexible, protein-based covering that surrounds the cell.
  2. Photosynthesis: They contain chloroplasts, which allow them to carry out photosynthesis and produce their own food. They are considered to be primary producers.
  3. Heterotrophic: They are also capable of heterotrophic nutrition, meaning they can absorb nutrients from their environment. They have a cytostome or mouth, an opening in the cell that allows them to ingest food particles.
  4. Movement: They move using their flagellum, which propels them through the water. They can also move in response to light, a behavior known as phototaxis.
  5. Reproduction: They reproduce through binary fission and multiple fission. In binary fission, the cell divides into two daughter cells.
  6. Sensory organelles: They have a unique organelle called the eyespot or stigma, which is sensitive to light and allows the organism to detect the direction of light.
  7. Variety: There are many different species of Euglena, each with its own unique characteristics. Some species are photosynthetic, while others are heterotrophic. Some species are free-living, while others are parasitic.
  8. Ecological role: Euglena play an important role in freshwater ecosystems as primary producers, and they are also important food sources for small aquatic animals such as zooplankton and small fish.

Morphology of Euglena

  • Euglena is a genus of single-celled protists that are classified as eukaryotes.
  • They have a variety of morphological features that are characteristic of their genus.
  • One of the most notable morphological features of Euglena is its ability to move using a whip-like structure called a flagellum.
  • They have a single flagellum that is located at the anterior end of the cell and is used for movement.
  • Euglena has chloroplasts, which are responsible for photosynthesis, giving the cell its green color. This is one of the reasons why Euglena is considered a photosynthetic organism.
  • They are also characterized by their unique eyespot, called a stigma, which is a small patch of pigmented cells that is sensitive to light.
  • The stigma allows Euglena to detect and respond to changes in light intensity, which is important for their photosynthetic abilities.
  • The cell of Euglena is surrounded by a flexible cell membrane, which encloses the cytoplasm and all the organelles.
  • It also contains a large central vacuole, which stores water and other materials.
  • They can absorb food with their cytostome.
  • A single, large, spherical or oval shaped nucleus lies near the center of the endoplasm, usually towards the posterior end of the body.
  • At the anterior end of the body, there is an invagination forming a permanent flask-shaped cavity called the reservoir.
  •  Associated with the reservoir occurs a dense osmoregulatory zone which includes a large central contractile vacuole. This vacuole is surrounded by several smaller accessory vacuoles. The whole thing is termed the contractile apparatus.

Why Euglena is a Plant?

  • Euglena is often referred to as a “plant-like” organism because it possesses some characteristics that are similar to those of plants.
  • One of the main reasons for this is that Euglena cells contain chloroplasts, which are organelles that are responsible for photosynthesis. Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy in the form of organic compounds.
  • Like plants, it uses this process to produce its own food through the conversion of carbon dioxide and water into glucose and oxygen. This process is also responsible for the green color of its cells, as the chlorophyll pigments that are present in the chloroplasts absorb light in the blue and red regions of the spectrum, but reflect green light.

Why Euglena is an animal?

Euglena is called an animal-like protist because it exhibits characteristics of both animals and plants. It has a flagellum for movement, which is a characteristic of animals. Additionally, it can ingest food, similar to animals. However, it also contains chlorophyll and is able to photosynthesize, like plants. Due to this unique combination of characteristics, Euglena is classified as an “animal-like protist”. It is a single-celled organism that belongs to the family Euglenidae. Some important reasons are given below:

  1. Absence of a cellulose cell wall.
  2. Presence of centrioles.
  3. Reserve food is paramylon which is not a true starch.
  4. Presence of a sensory organelle, the stigma.
  5. Moves from one place to another.
  6. Responds to various stimuli like animals.
  7. Can absorb food through the cytostome or mouth.


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The general characteristics of Euglena have been fully explained above. If you love our articles, consider reading more articles from us. Thank you.

Read more:

  1. Structure of Euglena with Labeled Diagram
  2. Locomotion(Movement) and Nutrition of Euglena | Diagram
  3. Reproduction of Euglena | Binary Fission, Multiple Fission & Encystment | Diagram
  4. General Characteristics of Trypanosoma gambiense | Diagram


  1. “Modern Textbook of Zoology Invertebrates” written by R. L. Kotpal.
  2. Euglena | Definition, Diagram
  3. Euglena Reproduction wiki

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