Introduction 

Today we discuss the Pseudopods, Amoeba shape, classification of amoeba’s nutrition mode, Reproduction of amoeba and size of Amoeba, amoeba binary fission, and the structure of amoeba.

This single-celled, Eukaryotic organism shows crawling instead of walking and sometimes can eat your brain. There are two types of organisms present in the nature Prokaryotes and Eukaryotes, which we have discussed in the previous blogs. Eukaryotes especially got recognition for the presence of well-defined nuclei and membrane-bound organelles.

But in the case of Amoeba, there are few exceptions in the different species of Amoeba. For example, the parasitic amoeba Entamoeba histolytica does not have the Golgi apparatus required for modifying and transporting proteins. Amoeba or ameba has a remarkable ability to alter its shape according to the surface on which it is present. One more fact of Amoeba is that it does not have legs but can still move from one place to another with its false feet. 

Pseudopods

The ability to alter shape is due to the expansion and retraction of its false feet called Pseudopods. Many microbiologists call it amoeboid also. Many well-known species of Amoeba include a brain eater called Naegleria Fowleri, an intestinal parasite E. histolytica. Thant Can cause dysentery and multicellular social Amoeba called Dictyostelium discoideum. In high school, we used to study Amoeba and their characteristics. Still many questions popups while studying it, for example.

Why does Amoeba have an irregular shape, and precisely which shape? 

How do Amoeba moves?

What is the nutrition of Amoeba?

What is its mode of reproduction? Etc. etc.

Structure of Amoeba 

The reason behind the irregular shape of the Amoeba is the structure Amoeba which is highly irregular due to the absence of a cell wall. In addition, amoebas are recognized for their special ability to protrude leg-like cytoplasmic extension called pseudopodia. These pseudopodia are used for the locomotion of the amoeba body, and this special type of locomotion is called amoeboid locomotion. Amoeboid locomotion is the most primitive locomotion in the animal. Amoebas are mostly used in scientific studies to determine the function and interaction between the nucleus and cytoplasm.

The body of Amoeba has basically divided into three parts the nucleus, cytoplasm, and plasma membrane. The double-layered plasma membrane is composed of lipids and proteins. The cellular content of the Amoeba is packed into the cellular membrane while DNA is enclosed in the nucleus. Almost all the organelles required for cellular function and behavior are present in Amoeba. But some exception includes E. histolytica posse’s small fluid-filled pouches instead of Golgi apparatus and perform a similar function. Some amoebas lack mitochondria but posse’s organelle in the replacement, like hydrogenosomes or mitosomes for energy production.  

Pseudopodia or false feet are the cytoplasmic leg-like structure protruded by the amoeba body for locomotion. These bulges of cytoplasm result from the coordination action of actin microfilaments pushing out the plasma membrane. Short-lived outward projections of cytoplasm are fluid-filled, and this semifluid material help amoeba to grab the surface and crawl in direction. You can imagine our White Blood Cells; yes, amoeba moves and looks similar to cells of higher organisms, that is, WBCs.  

The differentiation between the amoeba species is done by the appearance and internal structure of the pseudopods.

Classification of Amoeba

Since the initial time, the group called Amoeba has not existed separately. In contrast, the organisms who crawl are grouped under the class Protozoan. On the morphological and some character similarities, latter the group is separated. Historically amoebas are classified under the class or subphylum Sarcodina. Sardinas is not a monophyletic group whose members share common descent. The grouping of unicellular organisms that possess pseudopods or who can locomote by protoplasmic flow is called Sarcodinas.  

The classification firms on the following points as initially amoebas are neither get classified under plants, animals, nor fungi.

Amoebas Nutrition Mode 

As a Protozoa without cell walls, the Amoeba do not have mouth and anus structures separately. And they are not much demanding of their food items. Some consume bacteria, protist and some are detritivores who live on the dead organic material. Phagocytosis is the favorite mode of nutrition of many amoebas. Sometimes they take nutrition through pinocytosis mode by drinking the cell of prey.

During phagocytosis, they spread and open up their pseudopods around the prey and engulf it. Still, there is no specific location for the engulfment and excretion of food on their body. 

Reproduction and Size of Amoeba

Amoebas follow an asexual mode for reproduction through the binary fission process. They are mostly found in the stream water and at the bottom of freshwater. Their size varies around 2-3 micrometers depending on the external environment. On the other hand, some species like Pelomyxa palustris and Chaos carolinense are bigger and known as giant amoebas seen by naked eyes.

Apart from all this information, a very interesting fact about the amoeba Dictyostelium discoideum is on the starvation stage; it becomes a multicellular organism from the unicellular one. This special ability of Dictyostelium discoideum help it survive starvation and get spread during the nutritious condition.