Giant Cells

[Darth Raptor]

Biology adepts, help me out. Correct me if I'm wrong, but the upper limit on the size of unicellular organisms is the inability of water and its associated sollutes to effectively diffuse across large distances. This is why we don't have the giant amoebas and stuff like we have in fiction. The largest cell, IIRC, is a bacterium about the size of a grain of rice.

But what if eukaryotes evolved a kind of vascular network out of the fibers and tubules of the cytoskeleton? If water and nutrients are conducted across these vessels, wouldn't the problem be resolved? Could we then get a monster blob?

[Admiral Valdemar]

Or, rather than these Shoggoths you propose, we get many cells working together, specialising and producing a colony of super advanced cells. Wait, that's macroscale life.

Besides, the dynein transportation system and microtububles wouldn't support such a large system too well, it wouldn't be efficient enough. You need to compartmentalise, and that is best done with advanced eukaryotes working in unison to form a multiple redundant organ system utilising various special cells and tissues for different tasks.

If you want a blob monster, think of the Phantom from the Dean Koontz book and movie. It's a T-1000, but as a biologic.

[Ariphaos]

Biology adepts, help me out. Correct me if I'm wrong, but the upper limit on the size of unicellular organisms is the inability of water and its associated sollutes to effectively diffuse across large distances. This is why we don't have the giant amoebas and stuff like we have in fiction. The largest cell, IIRC, is a bacterium about the size of a grain of rice.

Well a yolk is, technically, a single cell, and neurons are also macroscopically long.

But what if eukaryotes evolved a kind of vascular network out of the fibers and tubules of the cytoskeleton? If water and nutrients are conducted across these vessels, wouldn't the problem be resolved? Could we then get a monster blob?

Think of it like... the cell nucleus eventually has to get messages to all parts of a cell, assuming said parts of a cell aren't there mostly to be inert while supporting growth. Along the way, proteins break down, get stuck, or are just generally rather slow.

Compare to a human, say, where parts of our reflexes are actually governed by our spinal cord rather than our brain. Eventually, the blob becomes more like egg yolk than terror.

[Lord of the Abyss]

A major problem is structural strength; there's a macroscopic sea plant that is a single cell; it's a single cell wall filled with cytoplasm and billions of cell nuclei. It can live in the sea, but lacks the structural strength to hold a shape out of the water.
I read about it years ago offline; I'm not sure, but after googling I think it's valonia

Valonia is said to be the largest single cell organism in the world. The growing ball has no cell wall or internal divisions of any kind.

[Darth Raptor]

Oh. The thing I was thinking of is the world's largest prokaryote. Bugger if I can remember it's name.

[wolveraptor]

The largest cell, IIRC, is a bacterium about the size of a grain of rice.

I'm sure that every eukarote is bigger than a prokaryotic bacterium. There's no way a bacterium could be the largest cell.

[Shroom Man 777]

Is it possible for a giant multicellular blob monster to exist?

[Lagmonster]

Is it possible for a giant multicellular blob monster to exist?

You can play an enormous game of 'stretching the truth' and drag out some of the cellular or plasmodial slime molds. There was a scare some few decades ago when people found larger versions of these blobs crawling out from under their porches. The things are so odd that they've been reclassified three times as observational techniques progress.

[Shroom Man 777]

What?

[GrandMasterTerwynn]

What?

You might have an enormously large plasmodial or cellular slime-mould that covers a couple square meters, but it would also be very thin. It would be less a blob monster than a mostly-flat sheet monster. And while they do move and can efficiently navigate mazes, they tend to do so very slowly and lack the internal strengthening necessary to be a credible threat to something human-sized.

Short answer, no.

[Junghalli]

But what if eukaryotes evolved a kind of vascular network out of the fibers and tubules of the cytoskeleton? If water and nutrients are conducted across these vessels, wouldn't the problem be resolved? Could we then get a monster blob?

You could get a large organism that was, in technical terms, a single cell but you'd be more likely to end up with something that resembled a conventional plant or animal.
Although I suppose if you've already got your mind set on a blob and just want a justification for how it can live without its interior layers dying in a matter of minutes it might work.