Behaviour of Amoebozoans

[bionewbie]

Why would excess water tend to accumulate in the Amoeba?

[kiekyon]

the concentration in amoeba is higher than the concentration in water.
therefore water tend to enter through osmosis

[bionewbie]

the answer sounds almost too simple ...

On a separate note but keeping on the topic of amoebas, how would one expect the movement to differ between Trypanosoma & Amoeba?

[kiekyon]

the answer sounds almost too simple ...

that's because it's a simple question

[Ken Ramos]

bionewbie asks:

On a separate note but keeping on the topic of amoebas, how would one expect the movement to differ between Trypanosoma & Amoeba?

Trypanosomes are flagellates belonging to the Phylum Mastigophora. Their primary means of locomotion is by the use of a whip-like extention known as a flagellum. This organell moves somewhat like a screw, drawing the organism along through what ever liquid medium it is found in. Amoebae on the otherhand move by means of their pseudopodia or "false feet." This is known as "amoeboid movement," which is not too uncommon in some other microorganisms. The amoeba makes a protoplasmic extention of itself and the rest of the cell flows into that extension to but it simply. Although movement by eruptive waves of protoplasm maybe the primary mode of locomotion for amoebae, there are some which do have flagella. These are known as amoebo-flagellates, most commonly found in myxomycota.

[bionewbie]

But what happens with the movement of Amoeba & Physarum? Aren't they both part of the Amoebozoans?

[Ken Ramos]

bionewbe asks:

But what happens with the movement of Amoeba & Physarum? Aren't they both part of the Amoebozoans?

Are you referring to Physarum as in Mycetozoia? If so, yes they are both part of the group of organisms we call amoebae. The amoebae associated with Myxomycetes, Mycetozoia, or Myxomycota; which ever taxia in which you wish to place them, there is still great debates over that between zoologists and botonists, have the ability to transition from the amoebo-flagellate form of locomotion to the amoeboid form of locomotion. There are also some other forms of amoebo-flagellates that are not associated with Mycetozoia, if I am not mistaken. However Physarum viride, didermoides and polycephalum are all part of the Phylum Sarcodina, Subphylum Hydraula, Superorder Acraseda, Class Alternatea, Subclass Mycetozoia, Order Physarida. (Ref: Jahns, How to Know the Protozoa, Second Edition, McGraw Hill Publishing)

[bionewbie]

Are you referring to Physarum as in Mycetozoia?

Well I mean Physarum as in a plasmoidal slime mold. All I know is that they stream along as plasmodiums. So I'm just wondering how their movement is similar / different from Amoebas.

[Ken Ramos]

bionewbe asked:

Well I mean Physarum as in a plasmoidal slime mold. All I know is that they stream along as plasmodiums. So I'm just wondering how their movement is similar / different from Amoebas

Oh, o.k. I see what you mean. Sorry for the misunderstanding. Actually there is not much if any difference in the streaming movements of microscopic amoebae and the plasmodium of myxomycetes. Both move by what is termed amoeboid movement, in which the pseudopodium is extended and the remaining protoplasm flows into it. The plasmodium is nothing more than thousands if not more amoebae or amoebo-flagellates fused together to make one giant multinucleate amoeba. So when you see a plasmodium you are actually seeing a single multinucleate cell, an amoeba.

If you will click on the attached image of the plasmodium I have here, you can see that it also has a multitude of pseudopodia and it uses its psuedopodia much the same way as do other amoebae. Even when the plasmodium feeds, it does so by phagocytosis, the engulfing of its prey or food and then surrounding it with digestive enzymes.

[Ken Ramos]

Here is another photograph you may find interesting. It is one of the same plasmodium feeding on the corpse of a small termite. The termite was in the decaying wood from which the plasmodium was taken.

Click on image for larger view.

[bionewbie]

bionewbe asked:

Well I mean Physarum as in a plasmoidal slime mold. All I know is that they stream along as plasmodiums. So I'm just wondering how their movement is similar / different from Amoebas

Oh, o.k. I see what you mean. Sorry for the misunderstanding.

No worries! Actually what you said was really useful. btw, your pictures were so cool!

Actually there is not much if any difference in the streaming movements of microscopic amoebae and the plasmodium of myxomycetes. Both move by what is termed amoeboid movement, in which the pseudopodium is extended and the remaining protoplasm flows into it. The plasmodium is nothing more than thousands if not more amoebae or amoebo-flagellates fused together to make one giant multinucleate amoeba. So when you see a plasmodium you are actually seeing a single multinucleate cell, an amoeba. :o

So, if the movements are similar, then what are the functions for the cytoplasmic movement of Physarum?

[Ken Ramos]

bionewbe asked:

So, if the movements are similar, then what are the functions for the cytoplasmic movement of Physarum?

A very good question you have asked here. To my understanding that has yet to be sufficently answered by biologist and protozoologist. Amoeboid movement or cytoplasmic streaming has yet to be fully understood, however there are many theories as to how it all comes about.

I refered to the protoplasmic extentions of the plasmodium as pseudopodia, I do believe I was wrong in that terminology. In Jahns book they are refered to as "myxopodia," which seems to be a more correct and descriptive term and are described as polytubular networks formed from oscillating streams of cytoplasm and are at the advancing margin of the "mycetozoan." Again terminology for these species is quite diverse. I would have refered to the mycetozoan as a plasmodium but I think that mycetozaon is a more collective term.

I wish that I could give you a better answer to your question but information on that subject is quite diverse and scattered. So, it is to my assumption, if I have not misunderstood your question, that the function of movement is much or exactly the same as what occurs with its microscopic counterparts and the cause of the cytoplasmic streaming or amoebiod movement is still being debated. There maybe someone else who is following this post, that may be able to shed a little light on the subject and I would be interested too in reading what they have to say but still it would not be given to absolute fact, as far as I know; because at my last reading, it was still being debated by biologists and protozoologist.

OBTW, thanks for your comment on the photographs. If you are interested go to my web page for a view of the set up used to take those photographs. The microscope is shown in the first photograph on the front page. Just click on the www icon at the bottom of my signature below on this page.