Euglena
Phylum : Protozoa-Unicellular organisms.
Sub-phylum : Sarcomastigophora-Locomotion by pseudopodia or flagella.
Class : Matigophora- Locomotion by flagella; body enclosed in a pellicle.
Sub-class : Phytomastigina-Nutrition holophytic; possess chromatophores.
Order : Euglenoidea-cytosome and cytopharynx present; flagellum single.
Genus : Euglena.
Habit and Habitat
Euglena is cosmopolitan in distribution and occurs in all stagnant fresh water ponds, pools and ditches containing decaying animal and vegetable matter. in the laboratory, it can be culture by placing a few Euglena in the culture medium prepared by boiling horse or cow dung in distilled water.
Structure
The animal body is spindle-shaped with a blunt anterior end, and a pointed posterior end. The outer covering , known as pellicle is firm and elastic and thus it gives a fixed shape to the animal. Beneath the pellicle, there are a few elastic fibers arranged obliquely and longitudinally.
The anterior end beare a funnel-like cytosome which leads into a short Cytopharynx. Near the base of the cytostome, there is a large pigment spot, known as stigma.
From the base of the cytostome arises a large flagellum which has two roots, joining with the basal grannule (blepharoplast) . Besides, a short filament also arises with a separate basal grannule, which soon after its origin unites with the anger one.
The cytoplasm is well differentiated into an outer thin, non-granular ectoplasm and an inner grannule, vacuolated endoplasm. In the endoplasm, there is a large, spherical nucleus situated almost centrally. Several chloroplast and amylum bodies occur suspended in the endoplasm. One to many contractile vaculoes are met at the anterior end and in close proximation with the cytopharynx.
Locomotion
Euglena shows two type of movements, viz (a) flagellar movements, and (b) euglenoid movements.
(a) Flagellar movements. They take place by lashing movement of flagellum in the water. The long highly contractile flagellum creates a series of waves of motion. This helps in propeling the body forward with a spiral rotation along the axis. This is the cheif means of locomotion in Euglena.
(b) Euglenoid movements. The body covering (or pellicle) is flexible and elastic in Euglena. It can change its shape according to the requirements of the animal. In this process, a wave of contractile pass along the body from anterior end and the animal creeps forward. The body becomes shorter and widen first at the posterior end. The oeganism thus progresses
slowly. These movements are caused by the stretching of protoplasm on the pellicle or by the action of myonemes of the ectoplasm. This type of movement is occasional.
Nutrition
Euglena show mixotrophic type of nutrition, as it exhibits more than one type of feeding. Commonly three types of nutrition viz. Holozoic, Holophytic and Saprophytic are met in Euglena.
1. Holozoic. The holozoic nutrition is rare in Eyglena. In the process, the animal takes in the living solid food particles and digest them.
2. Holophytic. During holophytic nutrition, Euglena is able to prepare its own food by photosynthesis. As a result paramylum is formed. The holophytic nutrition occurs in the presence of sun-light and the green pigment chlorophyll play an importantrole in the process.
3. Saprophytic. In poor light or darkness, Euglena exhibits saprophytic mode of nutrition. Dead and decaying matters dissolved in pond water are digested extracellularly and absorbed through the general body surface.
Respiration
It is simple and aerobic, Gaseous exchange take place by diffusion through general body surface.The dissolved oxygen of the surrounding water it taken in and carbon dioxide of the body passes out in a similar way.
Excretion and Osmoregulation
The cytostome, reservoir and contractile vacuoles are concerned with the excretion and osmoregulation.The tributary canals collect excess water and waste nitrogenous products from the cytoplasm and pour them in the contractile vacuole. The vacuoles diffuse into the reservoir from where water goes outside through cytopharynx and cytostome. Excretory wastes are also diffused through general body.
Reproduction
Euglena does not reproduce sexually. The usual mode of reproduction is by longitudinal binary fission also occur.
(a) Binary fission. This type of reproduction is very common in Euglena. When the environment conditions are favourable for growth, the animal ceases its activites and secretes a mucilaginous envelope around itself. The nucleus divides by simple mitosis. Other nuclear and extra-nuclear inclusions starts from the anterior end of the body. However the flagellum does not divide and goes for one individual while the other develops its own. The two daughter euglenae thus fromed lead a new life.
(b) Encystment and Multiple fission. During unfavourable condition, Euglena reproduces either by encystment or by multiple fission. During encystment, if secretes thick cyst of gelatinous mass of yellowish brown colour. It can withstand the adverse conditions of life. Onset of fevourable conditions result in the rupture of cyst and the animal starts an active life.
In multiple fission, during the encystment it may undergo several longitudinal binary fission. All of them remain entangled in a common cyst forming the palmella stage. When favourable condition commence, the cyst wall ruptures, the euglenae separate, regenerate the flagella and starts living normal and active life.
Systematic Position of Euglena
Euglena bears many characters which are common to both plants and animal. The botanists kept it in plant kingdom due to the presence of chloroplast, pyrenoids and holophytic mode of nutrition. However, the characters like the presence of myonemes, contractile vacuoles and euglenoid type of movement compel us to keep it in the animal kingdom. Furthermore, absence of a cellulose cell wall, the presence of paramylum and holozoic mode of nutrition strengthens this view. In animal kingdom, we treat it as member of phylum Protozoa due to its unicellular microscopic body and we include it in class Mastigophora bacause it has a flagellum for the movements.
Phylum : Protozoa-Unicellular organisms.
Sub-phylum : Sarcomastigophora-Locomotion by pseudopodia or flagella.
Class : Matigophora- Locomotion by flagella; body enclosed in a pellicle.
Sub-class : Phytomastigina-Nutrition holophytic; possess chromatophores.
Order : Euglenoidea-cytosome and cytopharynx present; flagellum single.
Genus : Euglena.
Habit and Habitat
Euglena is cosmopolitan in distribution and occurs in all stagnant fresh water ponds, pools and ditches containing decaying animal and vegetable matter. in the laboratory, it can be culture by placing a few Euglena in the culture medium prepared by boiling horse or cow dung in distilled water.
Structure
The animal body is spindle-shaped with a blunt anterior end, and a pointed posterior end. The outer covering , known as pellicle is firm and elastic and thus it gives a fixed shape to the animal. Beneath the pellicle, there are a few elastic fibers arranged obliquely and longitudinally.
The anterior end beare a funnel-like cytosome which leads into a short Cytopharynx. Near the base of the cytostome, there is a large pigment spot, known as stigma.From the base of the cytostome arises a large flagellum which has two roots, joining with the basal grannule (blepharoplast) . Besides, a short filament also arises with a separate basal grannule, which soon after its origin unites with the anger one.
The cytoplasm is well differentiated into an outer thin, non-granular ectoplasm and an inner grannule, vacuolated endoplasm. In the endoplasm, there is a large, spherical nucleus situated almost centrally. Several chloroplast and amylum bodies occur suspended in the endoplasm. One to many contractile vaculoes are met at the anterior end and in close proximation with the cytopharynx.
Locomotion
Euglena shows two type of movements, viz (a) flagellar movements, and (b) euglenoid movements.
(a) Flagellar movements. They take place by lashing movement of flagellum in the water. The long highly contractile flagellum creates a series of waves of motion. This helps in propeling the body forward with a spiral rotation along the axis. This is the cheif means of locomotion in Euglena.
(b) Euglenoid movements. The body covering (or pellicle) is flexible and elastic in Euglena. It can change its shape according to the requirements of the animal. In this process, a wave of contractile pass along the body from anterior end and the animal creeps forward. The body becomes shorter and widen first at the posterior end. The oeganism thus progresses slowly. These movements are caused by the stretching of protoplasm on the pellicle or by the action of myonemes of the ectoplasm. This type of movement is occasional.
Nutrition
Euglena show mixotrophic type of nutrition, as it exhibits more than one type of feeding. Commonly three types of nutrition viz. Holozoic, Holophytic and Saprophytic are met in Euglena.
1. Holozoic. The holozoic nutrition is rare in Eyglena. In the process, the animal takes in the living solid food particles and digest them.
2. Holophytic. During holophytic nutrition, Euglena is able to prepare its own food by photosynthesis. As a result paramylum is formed. The holophytic nutrition occurs in the presence of sun-light and the green pigment chlorophyll play an importantrole in the process.
3. Saprophytic. In poor light or darkness, Euglena exhibits saprophytic mode of nutrition. Dead and decaying matters dissolved in pond water are digested extracellularly and absorbed through the general body surface.
Respiration
It is simple and aerobic, Gaseous exchange take place by diffusion through general body surface.The dissolved oxygen of the surrounding water it taken in and carbon dioxide of the body passes out in a similar way.
Excretion and Osmoregulation
The cytostome, reservoir and contractile vacuoles are concerned with the excretion and osmoregulation.The tributary canals collect excess water and waste nitrogenous products from the cytoplasm and pour them in the contractile vacuole. The vacuoles diffuse into the reservoir from where water goes outside through cytopharynx and cytostome. Excretory wastes are also diffused through general body.
Reproduction
Euglena does not reproduce sexually. The usual mode of reproduction is by longitudinal binary fission also occur.
(a) Binary fission. This type of reproduction is very common in Euglena. When the environment conditions are favourable for growth, the animal ceases its activites and secretes a mucilaginous envelope around itself. The nucleus divides by simple mitosis. Other nuclear and extra-nuclear inclusions starts from the anterior end of the body. However the flagellum does not divide and goes for one individual while the other develops its own. The two daughter euglenae thus fromed lead a new life.
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Systematic Position of Euglena
Euglena bears many characters which are common to both plants and animal. The botanists kept it in plant kingdom due to the presence of chloroplast, pyrenoids and holophytic mode of nutrition. However, the characters like the presence of myonemes, contractile vacuoles and euglenoid type of movement compel us to keep it in the animal kingdom. Furthermore, absence of a cellulose cell wall, the presence of paramylum and holozoic mode of nutrition strengthens this view. In animal kingdom, we treat it as member of phylum Protozoa due to its unicellular microscopic body and we include it in class Mastigophora bacause it has a flagellum for the movements.
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