In Terms of Feeding What is Unique About the Euglena Compared to Other Protists

Table of Contents:

• Classification of Euglena
• Euglena Diagram
• Morphology and Anatomy
• Nutrition
• Reproduction

Euglena is a type of euglenoid. Euglenoids are unicellular microorganisms, that have a flexible body. They possess the characteristic features of plants and animals. Euglena has plastids and performs photosynthesis in light, but moves around in search of food using its flagellum at night. There are around 1000 species of Euglena found. They are found in freshwater, saltwater, marshes and also in moist soil.

Euglena Classification

Euglena is a genus of euglenoids. The classification of Euglena is contentious. They are kept in the phylum Euglenozoa or in the phylum Euglenophyta with algae due to the presence of chlorophyll. Since all the species of Euglena do not contain chloroplasts, they are kept in the phylum Euglenozoa. The class Kinetoplasteae in the phylum Euglenozoa contains non-photosynthetic flagellates known as Trypanosomes, which are parasitic and cause serious diseases in humans such as African sleeping sickness, leishmaniasis.

Euglena Structure with Diagram and Characteristics

Morphology and Anatomy

• Euglena has an elongated cell measuring 15-500 micrometres
• Mostly green in colour due to the presence of chlorophyll pigment
• Some of the species of euglena contain carotenoid pigments, which give it distinct colour like red
• Euglena is unicellular having one nucleus
• Euglena lacks the cellulose cell wall present in a plant cell
• There is a presence of a flexible outer membrane known as a pellicle, which supports the plasma membrane. The pellicle is composed of a proteinaceous strip and supporting microtubules. The pellicle gives flexibility to the cell and an ability to contract and change its shape
• A thin plasma membrane is present, which encloses the cytoplasm and cell organelles
• It contains a contractile vacuole which removes excess water
• There is inward pocket near the base of flagella called a reservoir, where contractile vacuole dispels excess water
• Various cell organelles such as mitochondria, endoplasmic reticulum and Golgi bodies are present

Nutrition

• Euglena contains chloroplast having chlorophyll. These chloroplasts have the green algal origin and seemed to have acquired due to endosymbiotic relationship
• They perform photosynthesis, but also require other organic nutrients and vitamins such as vitamin B₁₂
• Some of the photosynthetic euglenoids lose their chlorophyll when they grow in the dark and obtain nutrients heterotrophically from organic matter
• Some species of Euglena are also heterotrophs
• The heterotrophic species of Euglena either absorb organic compounds from the surrounding water or engulf bacteria and protists by phagocytosis within the food vacuoles
• The chloroplast of Euglena contains pyrenoids, which is used to synthesize paramylon, a ꞵ-1, 3 polymer of glucose
• Food is stored in the form of paramylon, which provides energy when there is no light
• Some species of Euglena produce an alkaloid known as euglenophycin, which is found to kill fishes
• Euglena is cultivated for large scale production in some countries like Japan for commercial production of paramylon. Some species of Euglena have shown to contain vitamin E (⍺-tocopherol) and high content of astaxanthin

Locomotion and Phototaxis movement

• It has an eyespot also known as stigma, that contains photoreceptors for detection of light and involved in phototaxis
• Light detected by the eyespot is focused on paraflagellar body
• One or two flagella are present, which help in locomotion
• Mostly two flagella are present, that originates from a small reservoir inside the cell
• One short flagellum is present, which does not protrude out of the cell, the long flagellum is used for swimming

Reproduction

• Euglena reproduces asexually by binary fission, they divide longitudinally
• Their lifecycle consists of a free-swimming and a non-motile stage
• It produces thick-walled protective cyst that can withstand unfavourable conditions, this is characteristic of a non-motile stage
• Some euglenoids make reproductive cyst under unfavourable conditions. Many Euglenoids gather together, leave their flagella and get enclosed in a gelatinous substance. Individual Euglena produces reproductive cyst, which produces daughter cells by binary fission. Under favourable conditions, these daughter cells become flagellated and come out of the mass. This is known as the palmelloid stage of the lifecycle.

Frequently Asked Questions

Are Euglena a plant or animal?

Euglena is a genus of unicellular, flagellated microorganisms. They possess characteristics of both plants and animals but are neither placed in the kingdom Plantae nor Animalia. They belong to the kingdom Protista.

Are Euglena prokaryotic or eukaryotic?

Euglena is a genus of eukaryotic, unicellular and flagellated microorganisms. They contain a well-defined nucleus and other cellular organelles such as mitochondria, endoplasmic reticulum, chloroplasts and Golgi bodies, etc.

Where is Euglena found?

They are found in freshwater, saltwater, marshes and also in moist soil.

Why Euglena is known as mixotrophs?

Euglena has chloroplasts and performs photosynthesis in light, but moves around in search of food using its flagellum at night. Some of the photosynthetic euglenoids lose their chlorophyll when they grow in the dark and obtain nutrients heterotrophically from organic matter. The heterotrophic species of Euglena either absorb organic compounds from the surrounding water or engulf bacteria and protists by phagocytosis within the food vacuoles.
Since they show both autotrophic and heterotrophic mode of nutrition, they are known as mixotrophic.

What are euglenoids?

Euglenoids are the best-known flagellates of the phylum Euglenozoa. Euglenoids have an outer protein layer called the pellicle. They are unicellular and biflagellate. Examples of euglenoids are Euglena, Trachelomonas, etc.

Also Check:

NEET Flashcards: The Living World

NEET Flashcards: Biological Classification

NEET Flashcards: Cell The Unit Of Life

NEET Flashcards: Cell Cycle And Cell Division

NEET Flashcards: Reproduction In Organisms

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Source: https://byjus.com/neet/euglena-structure-and-classification/

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