

Watching the anime "Parasyte - the maxim" I can't really see any of the
organisms shown as real parasites, from a biological/ecological viewpoint.

Can any of the different kinds of alien parasytes shown be classified as a
bona fide parasite?


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parasyte
Biologically speaking, is it true that there are no parasites in Parasyte?


I will use "parasite" (lower case, with an "i") to refer to the ecological
relationship, and "Parasyte" (upper case, with an "y") to refer to the manga
creatures.

* * *

From Wikipedia on [parasitism](http://en.wikipedia.org/wiki/Parasitism):

> Parasitism is a non-mutual symbiotic relationship between species, where one
> species, the parasite, benefits at the expense of the other, the host. (...)
> Unlike predators, parasites typically do not kill their host (...)

Then, on [decapitation](http://en.wikipedia.org/wiki/Decapitation):

> This form of injury invariably results in death (...)

* * *

So, on the three kinds of Parasytes:

  * The ones that "eat" the brain and take over the head, they already killed their hosts upon infection. So they **are not parasites** because they first **kill the host** , then inhabit the corpse. **Parasitism** is a kind of **symbiosis** , meaning that **both** organisms must be **alive**.

From [Livescience](http://www.livescience.com/42301-brain-death-body-
alive.html):

> A person is considered brain-dead when he or she no longer has any
> neurological activity in the brain or brain stem — meaning no electrical
> impulses are being sent between brain cells.

The head of those bodies is the Parasyte, the original human head long gone,
consumed by the Parasyte larvae. So there is no ecological relationship
between living organisms. The Parasyte simply took over the corpse of the
human they killed. Such is the case when a Parasyte changes bodies too, like
when

> Shinichi's mom is beheaded by the car crash Parasyte, because it needed a
> female body to inhabit.

We can then infer that these head-Parasytes are not parasites. The
relationship between them is [called
Metabiosis](http://en.wikipedia.org/wiki/Commensalism#Metabiosis).

  * The co-inhabiting Parasytes, like Migi and Joe, they are really either [mutualist symbiotes](http://en.wikipedia.org/wiki/Mutualism_%28biology%29) because the Parasyte provides his host with augmented abilities and protection from a predator (other Parasytes), and even if we think of a co-inhabiting Parasyte that stays dormant on his host, it would still be a case of [phoresis or inquilinism commensalism](http://en.wikipedia.org/wiki/Commensalism#Types). 

The human in the case of a commensalist symbiote would not be harmed or
hindered, because the Parasyte emulates the body part it "ate" and the
commensalist Parasytes are not too eager to kill their host since their
primary drive is survival, and as Migi states, without eating the brain they
do not know how to control a whole human body.

  * The colony Parasytes, like

> Miki and Gotou

are a colony of same-species organisms mimicking a human body. They are also
not parasites.

* * *

From the bullet points above, we can say that none of the Parasytes shown in
the manga or the anime (so far) are not really parasites.


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There are Parasites in Parasyte, and they are called Humans, they are
Parasites for Earth, I think a Parasyte told Shinichi and Migi this in one of
the earlier episodes, I never saw the Parasytes as Parasites, honestly... I
even felt sad when they died cause they did not do anything wrong, its like a
lion getting shot because he ate a deer :/ Humans can make these choices for
other creatures, and then say they are the most humane thing on the planet,
and claim everything on earth is equal, yet eat animals, its hypocritical and
the series (IMO) is trying to show Humans are Parasites.

P.S. "Can any of the different kinds of alien parasytes" Did you watch the
Anime even? They are from earth... The end they say "we are all born here"


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Parasytes might not be parasites as they are defined in our world, because
they are (from space or not) alien creatures. They did not evolve here and
don't share our roots and typical mechanics. @Mindwin made good points about
this and why our current definition don't include them - although I think we
would adapt it so that they mach it. The human bodys may be brain dead but
they still have traits of life ([See
Wikipedia](https://en.wikipedia.org/wiki/Life#Biology)):

Homeostasis: still sweating and so on  
Organization: still made of living cells  
Metabolism: Still need nutrients - human flesh or regular food  
Growth: We can't be sure here but there is no reason why a child's body should
stop growing after be infected by a Parasyste (maybe the Parasyte could stop
growth by not mimic the thyroid but still the human body is able to grow). At
least we know, that the human body will grow old and die. (see [Mr.
B](http://kiseijuu.wikia.com/wiki/Mr._B))  
Adaptation: Hard to prove but I think we can agree that they e.g. grew scarf-
skin.  
Response to stimuli: Of course the nerves are still working, autonomic nervous
system is at least partly independent of the brain.  
Reproduction: Not reiko and A had a child but their human bodies. It would be
possible to maintain human population if there were so many Parasytes that
they ate all of us and than started to make human babys themself

But I want to stress another point most people are missing and which (imho) is
one of the most important in the entire story (It is not pointed out as such
but I do care about it more than about others):

Humankind is an organism itself!

You say that human are parasites to earth - a single Human is not, Human kind
might be. Reiko says that a single human is weak compared with Parasytes but
that Human have another consciousness and when Parasyte attack it, they will
lose. If we understand human kind as an organism, Parasytes are parasites to
it. The organism "humankind" grew too much and now Parasytes appear, consuming
some of it's ressources like a tapeworm and slowing it's grow without killing
it. After beeing overrun by the Parasy/ites, humankind's immune system started
to gather forces against them and became mostly immune to them. If there would
be a new wave of parasytes, we could easily detect them and know what wapons
kill them - they would be ways less effective but still some of them will
allways stay in the organism. It is a perfect match to an upscaled infection.


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