In our last class we talked about paramecium, I hope we all understand everything about paramecium now, if you have any question or any complain use the drop box and I will get back to ASAP [ AS SOON AS POSSIBLE].
Today we are going to be discussing about EUGLENA. SO Leettt gooo
What is an euglena?.
Euglena is a minute organism which has the characteristics of both plants and animals.
a] Habitat : it is found in a stagnant fresh water such as pools and ponds which contain decaying organic matter.
b] Locomotion : Euglena moves by the whiplike action of a single flagellum. As Waves pass along the flagellum from the base to the tip. The organisms rotate as it moves. It can also move by the contraction of fibrils in its body called Myonemes.
These contraction brings about a sequence of changes in the shape and cause euglenoid movement.
c] Feeding : Euglena viridis is a green and photo-autotrophic organism.
The Euglena absorb carbon dioxide from the water in which he lives and energy from the sunlight to carry photosynthesis. It make up its nitrogen requirements by absorbing nitrogenous substances such as amino acids from the water.top↑
In some species of Euglena, the flagellum sets up a whirl pool, which carries small organisms into the gullet, and in these species, there are absent of pellicle that is it has no pellicle, and digested in the cytoplasm. Some species of Euglena lacks chlorophyll and are colourless. They nourish themselves by extracellular digestion, and absorption of organic materials. If an Euglena is kept in a dark place, the green species of euglena loses chlorophyll. But they will continue to live if supply with organic food material.
d] Structure: Euglena is a microscopic organisms of about 0.125mm long. It has a definite share, which is slender, and tapers towards each end. The font end is blunt and the hind end is pointed.
Euglena is green because it contains green chloroplasts. In some species, these chloroplasts are rod-shaped and are arranged in the form of a star in the middle portion of the body. In other species, the chloroplasts may be spherical and are scattered in the cytoplasm. The body surface is covered with a thin tough material called pellicle. Which is flexible and allows the organism to alter its shape for short period of time during a form of movement known as Euglenoid motion.top↑
At the anterior end is a flask shaped structure called gullet. From the bottom of this gullet arises a long filament called flagellum.
On one side of the gullet is a red spot, which is sensitive to light and it is known as eye spot. Near the gullet is the contractile vacuoles.
The cytoplasm is differentiated into an outer thick cytoplasm called ectoplasm and an inner liquid cytoplasm called endoplasm. In the endoplasm there are granules of paramylum, this is a type of carbohydrates stored by this organisms [Euglena]. And this nucleus is located in the endoplasm.
e] Respiration : It absorbs oxygen from the water through its entire body surface and uses it for respiration.
f] Osmoregulatiom : There is one contractile vacuoles, with tributary canals, which collects excess water from the cytoplasm and discharges it into the gullet.top↑
g] Excretion: Euglena excrete by diffusing the waste materials[Carbon dioxide and nitrogenous ] through the external body surface from it body.
h] Sensitivity : Euglena viridis moves towards a source of light.
It also reacts to harmfull chemicals by turning and moving away.
I] Reproduction: Euglena reproduces asexual only by binary fission.
A fully grown individual divides lengthwise beginning from the anterior to the posterior end.
a] Structure : Chlamydomonas is a microscopic, unicellular and green alga. Chlamydomonas has a constant, oval shape.top↑
b] Habitat: Chlamydomonas lives in fresh water pond and ditches.
c] Feeding : Chlamydomonas has a posterior part, in the posterior part is one cup-shaped chloroplast with a pyrenoid embedded in it.
The pyrenoid is a centre for the storage of food.
d] Chlamydomonas :has a cell wall which encloses the cytoplasm and nucleus. It has two flagella at the anterior end , within the cytoplasm in the anterior end and it also have two contractile vacuoles.top↑
we should stop here for today. Next class will be on living cells as a colony.
Next Topic :Living Cell As A Colony