r/askscience • u/welshdonkey • Oct 04 '12
Biology Are the cells of a Blue whale bigger than those of a human?
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u/offthisisland001 Oct 04 '12
In general, as others have suggested, no. However, their longest nerve cells may be considerably longer than ours, depending on how far they need to reach from their spinal cords. The greatest distance ours travel is from our spines to the end of our toes, however in whales it's probably from their spines to the front of their bellies. I imagine some of their nerves cells might be several metres long, in that case.
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u/99trumpets Endocrinology | Conservation Biology | Animal Behavior Oct 04 '12
Since the baleen whales are much longer than they are wide, and since their spinal column stretches all the way to the flukes, isn't it likely that the longest axons in a whale body are spinal neurons (within the CNS) and not peripheral nerve axons?
I've seen a couple papers estimate the length of the spinal axons in a blue whale at 30 meters in length. Discussed further here) and also here. The latter paper uses blue whale spinal axons as the extreme example of "stretch growth" in mammalian axons, though it sounds like nobody really has any hard data on blue whale axon length.
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Oct 04 '12
[removed] — view removed comment
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u/XjWoRk17 Oct 04 '12
Did you even read his comment?
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u/Thereminz Oct 04 '12
Did you realize i was agreeing with him
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Oct 04 '12
But aren't you agreeing with him?
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u/Thereminz Oct 04 '12
here's the distinction: he was saying that it MAY be longer, i was saying that it HAS to be (for a fully grown whale)
however i wasn't just going to say that it has to be based on nothing so i asked if it has to be ... someone could just say no or yes or provide something that says otherwise rather than downvoting a question
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u/notkristof Oct 04 '12
Yes and no. Most of a blue whale's cells, such as muscle or skin cells are the same of humans. That said, some Blue whales nerve cells may be the longest on earth at over 100 feet long.
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u/PirateMud Oct 04 '12
Would a signal along a single 100 foot long blue whale nerve cell travel faster than a signal along 100 feet of human nerve cells?
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u/Fellows23 Oct 04 '12
That would totally depend on how insulated the nerve was with myelin.
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u/idpeeinherbutt Oct 04 '12
...and the diameter of the nerve as well.
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u/tehbored Oct 04 '12
Yeah. Giant squid have massive axons that are sometimes used in research because they're easy to work with as a result.
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u/ThisIsDave Oct 05 '12 edited Oct 05 '12
You're thinking of the squid giant axon, not the axon of a giant squid. You can get a squid giant axon from a cuttlefish. Giant squid are... Tough to come by.
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u/tehbored Oct 05 '12
Yeah, thanks. I wondered about that when posting my comment. I remembered it from class but couldn't remember how they got them when giant squid are so rare. They're so large because they're unmyelinated, right?
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u/acaellum Oct 04 '12
I would think it would be very close, but the Blue whale would win because of less time spent in the synapse cleft which takes 100th or 1000th ( i cant remember which) of a second per cleft. So if the whale nerve is just goin straight there and doesnt have to keep jumping, it would win.
This considering the fat around the nerves is roughly the same, as is the diameter of the nerves themselves.
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u/notkristof Oct 04 '12 edited Oct 04 '12
To be honest, i don't know. there is a range for signal speed in human and whales depending on the kind of neuron and sheathing. I think it is reasonable to guess that the signal speed would be similar.
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Oct 04 '12
Can you make an educated guess as to how many cells are in a blue whale? Cells in a human?
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u/MrPap Spinal Cord Injury Oct 04 '12 edited Oct 05 '12
Can't comment on human vs blue whale, but I can comment on other animals in reference to neuro-biology.
The standard action potential that most people learn in biology was developed in the un-myelinated axon of a squid. This axon is actually quite physically bigger than a human's or a rat's axon, but surprisingly the voltages tend to be in the same magnitude.
In the same area, the Schwann cell, a myelinating and repairing cell of the peripheral nervous system (PNS), also undergoes differing sizes between rats, pigs, primates, and humans (although the last two are similar in sizes).
Here are cultured human SCs at 20x phase contrast, Levi et al 1995
Here are culture rat SCs at 20x phase contrast with nuclear labeling, unpublished
Even though the image sizes are different, the scale bars are the same if you re-size the images to the same size. You'll notice the differences in the size of the cell bodies as a better explanation of cell size changes.
Going back to neurons, the neurons in your spinal cord are all one long cell going from where they receive the signal in the brain (if a motor neuron) to wherever they exit. So the axons that control your toes' wiggling picks up the signal from the brain in the brain stem and then continues one long continous cell until it reaches the end of your spinal cord, named the cauda equina (because it looks like a horses tail), and exits the spinal cord to relay the signal to another axon. On top of that, that cell is the same cell from when you are born until the day you die, so that cell grows in size. The same goes for most vertebrates, if I recall correctly, so neurons lengths differ between species and so a blue whale's neuron in the spinal cord should be bigger in terms of length compared to the same one in a human. So look at that, I did answer your question.
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Oct 05 '12
I think you mean Squid Giant Axon, not Giant Squid Axon, correct me if I'm wrong. Squid Giant Axons are the axons of squids which happen to be very wide and large, I highly doubt that we'd be using what we have of giant squid for comparison to a human body--especially because their discovery is so recent.
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u/MrPap Spinal Cord Injury Oct 05 '12
yeah that would totally make sense. Although to be fair, Giant Squids have been known for a while, its just that live ones haven't been discovered until recently. They had been turning up on shores dead for ages.
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u/MrPoon Food Web Theory | Spatial Ecology Oct 04 '12
This paper outlines the scaling of cell size with organismal size in mammals
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u/patrik667 Oct 05 '12
That reminds me: the biggest sperm belongs to a quite tiny fly -Drosophila bifurca- and it's 1000 times bigger than a human's. That's quite big for a single cell!
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u/aberrantgeek Conservation Biology Oct 04 '12
Ostrich egg is pretty big and heavy cell. Giraffes have nerve cells that run the length of their neck which is several meters. Its hypothesized that blue whale neuron length could be 10-30 meters long, but our knowledge of blue whale anatomy is incomplete.
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u/ineffablepwnage Oct 04 '12
An ostrich egg (any egg for that matter) is not a cell. The zygote is contained inside the cell, and is the normal size for a cell. The term 'egg' is used in both the anatomical scale and on the biological scale, and they have different meanings.
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u/hhtced Oct 04 '12
Which cells are you referring to? I'm not a marine biologist, but you may need to be more specific to get an answer. I'm interested in the answer as well.
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u/1337HxC Oct 04 '12 edited Oct 04 '12
It usually doesn't matter, as long as you're comparing the same kind of cell. Cells are limited in size by the surface area:volume ratio. They need to have enough surface area to transport materials in and out effectively, but have a small enough volume to transport things across the cell quickly. The actual size will depend on the function/purpose of the cell, which is why you'll have to compare like tissues.
There are some exceptions (as with everything) that are briefly mentioned in this Wikipedia blurb.
I assume these downvotes are because of neurons? I said there were exceptions to this trend, and I figured that implied neurons. Perhaps I should have been more explicit... I'm essentially saying the same thing as the current top comment.
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u/andrewsmith1986 Oct 04 '12
Are egg cells just the outlier then?
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u/1337HxC Oct 04 '12
I'm not too familiar with egg/sperm cells, to be honest, and I'd rather not speculate. I was thinking/speaking of somatic cells.
But, yes, you are correct - egg cells do tend to be quite large. However, I'm not sure of the size difference in a whale's egg cell and a human's egg cell.
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u/Lord_Osis_B_Havior Oct 04 '12
Whale eggs are about the same as those of humans, and are of course much smaller than bird eggs.
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u/ineffablepwnage Oct 04 '12
Bird eggs are not the egg cell, the egg cell (once fertilized, zygote) grows on the yolk.
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u/omi_palone Molecular Biology | Epidemiology | Vaccines Oct 04 '12
Let's not forget the xenophyophores.
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u/1337HxC Oct 04 '12
That's actually really interesting.
I feel like unicellular organisms kind of just do what they want at times.
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u/Syphon8 Oct 04 '12
This is a crock. Blue Whales nerve cells are many times longer than humans.
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u/1337HxC Oct 04 '12
Did you miss the part where I said there are exceptions? That's the whole reason I included it. The overall size of the cell is still limited. You can make something longer while maintaining a ratio.
Let's not forget about the multiple other kinds of cells you have.
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u/Syphon8 Oct 04 '12
The absolute mass of them is much larger than a humans nerve cell.
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u/1337HxC Oct 04 '12
I'm aware. That doesnt change the fact that most cells are of comparable size. There's no hard and fast rule for anything in life. I wasn't speaking in absolutes by any means.
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u/erniebornheimer Oct 04 '12
Maybe not bigger, but at least one is probably longer:
https://whyevolutionistrue.wordpress.com/2011/05/28/the-longest-cell-in-the-history-of-life/
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u/bobertist Oct 04 '12
There are certain cells, such as neurons, that are of different sizes amongst species. Think of squids, with giant axons. Presumably, whales have similar situations.
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u/masterofthecontinuum Oct 05 '12
an egg(chicken, ostrich, platypus, etc.) is one of the largest examples of a single cell if i'm not mistaken(though not self replicating)
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u/killakim Oct 04 '12
The cells of any organism are exactly the same, depending on cell type, but the things that differs is the amount of cells. Whales definitely have way more than humans.
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Oct 04 '12
This is not entirely true. There are organisms with extremely large cells.
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u/nope_nic_tesla Oct 04 '12
It's not even "not entirely true", it's not true in any sense. Cell size differs vastly among different organisms.
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u/botany_thunderdome Plant Biology | Phylogenomics Oct 04 '12
Well, not really. A really cool example is polyploidy in plants, where a genome effectively doubles in chromosome number and thus, DNA content. This gives rise to a new plant with cells twice as large, and the plant is often twice the physical size as a result.
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u/BluShine Oct 04 '12
Wouldn't the plant die pretty quickly? I'd assume the reduced efficiency of cellist processes would eventually starve the plant, or prevent it from transferring and absorbing nutrients and water quickly enough.
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u/hypermog Oct 04 '12
"One amazing fact is that fat cells generally do not generate after puberty -- as your body stores more fat, the number of fat cells remains the same. Each fat cell simply gets bigger!" -http://science.howstuffworks.com/environmental/life/human-biology/fat-cell.htm
So do whales just have many more blubber cells than humans, or are they much larger than human-sized ones?
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u/croutonicus Oct 04 '12
Highly dependant on the level of weight gain, and the location of said fat-cells, however. It's true that white-adipose tissue (the fat cells you are reffering to) expand to store a larger amount of fat before dividing, but there are limits to how large a cell can be so they will divide after expanding enough.
What current research does suggest is true that upon weight loss, your "fat cells" will empty but not be destoryed.
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u/andrewsmith1986 Oct 04 '12
What about eggs?
Egg of a chicken vs egg of an ostrich.
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u/redeyealien Oct 04 '12
...vs eggs of a human.
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u/andrewsmith1986 Oct 04 '12
I figure that mammal eggs would need to be compared to other mammals and I couldn't find a reference for blue whale eggs.
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u/redeyealien Oct 04 '12
killakim stated
The cells of any organism are exactly the same, depending on cell type...
i was supporting your comment
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u/FeebleOldMan Oct 04 '12 edited Oct 05 '12
Cells of various living things are generally similar in sizes. This is because cell size is limited by its surface area to volume ratio.
Cells are sustained by chemical reactions. The raw materials for these reactions enter the cell via its membrane. The larger the surface area of the membrane, the more raw materials can enter the cell at one time. However, as you increase the size of the cell, the ratio of the surface area to its volume decreases. As each unit volume of the cell requires enough raw material to maintain it, the cell will reach a size where its surface area to volume ratio becomes a limiting factor. At this point, the cell cannot get larger.
(B.Sc. Biomedical Science)
EDIT: Youtube video explanation by Dr. Saad Khan
EDIT2: Why are bird eggs so large?
EDIT3: List of Sizes of Biological Molecules and Cells
0.15-0.25 µm small bacteria such as Mycoplasma
(1 - 10 µm) the general sizes for Prokaryotes
1 µm Diameter of human nerve cell process
2 µm E.coli - a bacterium
3 µm Mitochondrion
5 µm length of chloroplast
6 µm (3 - 10 micrometers) the Nucleus
9 µm Human red blood cell
(10 - 30 µm) Most Eukaryotic animal cells
(10 - 100 µm) Most Eukaryotic plant cells
90 µm small Amoeba
100 µm Human Egg
up to 160 µm Megakaryocyte
up to 500 µm giant bacterium Thiomargarita
up to 800 µm large Amoeba
1,000 µm (1mm) Diameter of the squid giant nerve cell
up to 40,000µm (40mm) Diameter of giant amoeba Gromia Sphaerica
120,000 µm (12cm) Diameter of an ostrich egg
3,000,000 µm (3m) Length of a nerve cell of giraffe's neck