# "Animals that are impossibly hard to kill" **URL:** \ **Category:** Factual Questions\ **Created:** [March 31, 2010, 11:25pm UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509 "2010-03-31T23:25:17Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![TNWPsycho](https://avatars.discourse-cdn.com/v4/letter/t/47e85d/32.png) [@TNWPsycho](https://boards.straightdope.com/u/TNWPsycho)\ **Post date:** [March 31, 2010, 11:25pm UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/1 "2010-03-31T23:25:17Z")
I was reading this article on [www.cracked.com](http://www.cracked.com) (i know, not the best source for legitimate stuff) But check [this out](http://www.cracked.com/article_18471_5-animals-that-are-terrifyingly-hard-to-kill_p2.html). Whats up with the “immortal jellyfish?” ---
**Author:** ![Superfluous\_Parentheses](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@Superfluous\_Parentheses](https://boards.straightdope.com/u/Superfluous_Parentheses)\ **Post date:** [March 31, 2010, 11:27pm UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/2 "2010-03-31T23:27:47Z")
They’re not immortal; they just don’t die of “old age”, as far as I can see. I imagine that’s true of over 99% of individual organisms. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [March 31, 2010, 11:57pm UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/3 "2010-03-31T23:57:06Z")
- "The Lion’s Mane!! The Lion’s Mane!!!\* They should add _amoeba_ to that list. They’re more immortal than jellyfish. ---
**Author:** ![Perciful](https://avatars.discourse-cdn.com/v4/letter/p/b38774/32.png) [@Perciful](https://boards.straightdope.com/u/Perciful)\ **Post date:** [April 1, 2010, 12:38am UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/4 "2010-04-01T00:38:36Z")
I’m glad it is just jellyfish that can do this! It’s very sci-fi - Miglietta has learned that, unlike other species, Turritopsis dohrnii has the uncanny ability to reverse its development in times of crisis. For example, if it is in danger of starvation or has sustained a life-threatening physical injury, this particular species of jellyfish is able to transform all of its living cells into a younger, more resilient state through an astounding process called transdifferentiation. During this process, the jellyfish first turns itself into a globular cyst, then the cyst reverts back into a polyp colony. Since the polyp colony is basically the first stage of its life, the immortal jellyfish is essentially able to ‘restart’ its entire life process, creating new replicas that are free of the ailments that caused the forebear to initiate transdifferentiation in the first place.\* Read more at Suite101: ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [April 1, 2010, 2:09am UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/5 "2010-04-01T02:09:23Z")
I do not know why this is suddenly all over the internet _now_, since the science seems to go back to the 1990s, but it appears to be legit: [http://www.biolbull.org/cgi/reprint/190/3/302](http://www.biolbull.org/cgi/reprint/190/3/302) [pdf download] Anyone up for founding a new religion? 😃 ---
**Author:** ![The\_Great\_Philosopher](https://avatars.discourse-cdn.com/v4/letter/t/3ec8ea/32.png) [@The\_Great\_Philosopher](https://boards.straightdope.com/u/The_Great_Philosopher)\ **Post date:** [April 1, 2010, 2:33am UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/6 "2010-04-01T02:33:01Z")
[Wiki](http://en.wikipedia.org/wiki/Immortal_jellyfish) says they die a lot - they get eaten or die of disease - it’s just that if they manage to not die, they can revert back and start all over again, and keep doing that indefinitely. I’m pretty disappointed, I was hoping those things would literally be un-killable, no matter what you did to them… ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [April 1, 2010, 3:31am UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/7 "2010-04-01T03:31:16Z")
How about Flatworms? > [@](#): > > When a flatworm is cut in two pieces, each half can grow and develop into a new worm. As it has no blood, it will not bleed to death when it is cut. Any part of the branched tube can digest food, so neither part will starve while it is developing into a whole animal. > > Sometimes fresh-water flatworms divide into two worms by splitting lengthwise; sometimes by splitting crosswise. > > \ > > If you do not feed them, flatworms will absorb their own bodies and may continue to live for a month or more without any other food. > > SOURCE: [http://www.pond-life.us/pond-life-flatworm-1.html](http://www.pond-life.us/pond-life-flatworm-1.html) ---
**Author:** ![Snarky\_Kong](https://avatars.discourse-cdn.com/v4/letter/s/a183cd/32.png) [@Snarky\_Kong](https://boards.straightdope.com/u/Snarky_Kong)\ **Post date:** [April 1, 2010, 6:07am UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/8 "2010-04-01T06:07:22Z")
> [@The\_Great\_Philosopher](#): > > [Wiki](http://en.wikipedia.org/wiki/Immortal_jellyfish) says they die a lot - they get eaten or die of disease - it’s just that if they manage to not die, they can revert back and start all over again, and keep doing that indefinitely. I’m pretty disappointed, I was hoping those things would literally be un-killable, no matter what you did to them… Considering we can turn matter into energy, I think this is unlikely for any living thing. ---
**Author:** ![psychonaut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/psychonaut/32/4655_2.png) [@psychonaut](https://boards.straightdope.com/u/psychonaut)\ **Post date:** [April 1, 2010, 7:20am UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/9 "2010-04-01T07:20:45Z")
> [@CalMeacham](#): > > They should add _amoeba_ to that list. They’re more immortal than jellyfish. Amoebae aren’t animals, though. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [April 1, 2010, 7:40am UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/10 "2010-04-01T07:40:46Z")
> [@psychonaut](#): > > Amoebae aren’t animals, though. They were when I went to school (apparently they have their own kingdom now, though :(). ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [April 1, 2010, 11:53am UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/11 "2010-04-01T11:53:31Z")
> [@Whack-a-Mole](#): > > How about Flatworms? You can kill them if you cut them up enough. I forget the limit - I think you can cut them into over 200 parts and still have them regenerate, though it varies from part to part. Let’s not forget sponges, which you can blenderize into individual cells, which will then spontaneously reassemble back into little sponges. I’d also argue that in a very real sense, every single bacterium alive today is arguably the same as the first cell to ever evolve. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [April 1, 2010, 12:20pm UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/12 "2010-04-01T12:20:36Z")
> [@Smeghead](#): > > Let’s not forget sponges, which you can blenderize into individual cells, which will then spontaneously reassemble back into little sponges.. I’ve heard this several times but I’ve never seen a reliable cite. I find it hard to believe that the cells will actually regroup, T-1000 style. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [April 1, 2010, 12:50pm UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/13 "2010-04-01T12:50:40Z")
It happens. I most recently saw it demonstrated on a BBC documentary about the cell. It’s not as impressive as it sounds, though. It helps that sponges are very simple organisms, with only a couple of cell types. It doesn’t take much signaling for them to organize themselves. The reorganized sponge won’t look identical to the original - it’ll just be a new lump of sponge. ---
**Author:** ![SoulFrost](https://avatars.discourse-cdn.com/v4/letter/s/f07891/32.png) [@SoulFrost](https://boards.straightdope.com/u/SoulFrost)\ **Post date:** [April 1, 2010, 1:28pm UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/14 "2010-04-01T13:28:31Z")
> [@Perciful](#): > > I’m glad it is just jellyfish that can do this! It’s very sci-fi > > - Miglietta has learned that, unlike other species, Turritopsis dohrnii has the uncanny ability to reverse its development in times of crisis. For example, if it is in danger of starvation or has sustained a life-threatening physical injury, this particular species of jellyfish is able to transform all of its living cells into a younger, more resilient state through an astounding process called transdifferentiation. During this process, the jellyfish first turns itself into a globular cyst, then the cyst reverts back into a polyp colony. Since the polyp colony is basically the first stage of its life, the immortal jellyfish is essentially able to ‘restart’ its entire life process, creating new replicas that are free of the ailments that caused the forebear to initiate transdifferentiation in the first place.\* > > Read more at Suite101: Using different methods, other organisms also achieve immortality. [Henrietta Lacks](http://en.wikipedia.org/wiki/Henrietta_Lacks) was not immortal, but her cancer cells were. ---
**Author:** ![Perciful](https://avatars.discourse-cdn.com/v4/letter/p/b38774/32.png) [@Perciful](https://boards.straightdope.com/u/Perciful)\ **Post date:** [April 1, 2010, 1:55pm UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/15 "2010-04-01T13:55:18Z")
> [@SoulFrost](#): > > Using different methods, other organisms also achieve immortality. [Henrietta Lacks](http://en.wikipedia.org/wiki/Henrietta_Lacks) was not immortal, but her cancer cells were. This is fascinating! How come I never heard of this before? ---
**Author:** ![TruCelt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/trucelt/32/523_2.png) [@TruCelt](https://boards.straightdope.com/u/TruCelt)\ **Post date:** [April 1, 2010, 3:38pm UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/16 "2010-04-01T15:38:30Z")
Bed bugs. Ir ead an article once where the woman whose house was infested said she put a bug in a plastic container inthe fridge to see how long it could live int he cold with no food. A month later she had a colony in there on it’s thrid generation of bugs. An adult can go a whole year without eating, and still create up to 500 viable eggs. Many lines are now immune to most pesticides. They are nearly unsquishable due to their size and shape. Cutting them in half does work, but if there are any eggs left behind they will likely hatch successfully. ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [April 1, 2010, 3:57pm UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/17 "2010-04-01T15:57:25Z")
> [@njtt](#): > > They were when I went to school (apparently they have their own kingdom now, though :(). Splitters! ---
**Author:** ![conway](https://avatars.discourse-cdn.com/v4/letter/c/ec9cab/32.png) [@conway](https://boards.straightdope.com/u/conway)\ **Post date:** [April 1, 2010, 5:48pm UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/18 "2010-04-01T17:48:03Z")
> [@Perciful](#): > > This is fascinating! How come I never heard of this before? It’s an interesting story; a new book is out if you want to learn more: > **[The Immortal Life of Henrietta Lacks: Skloot, Rebecca: 9781400052172:...](https://www.amazon.com/Immortal-Life-Henrietta-Lacks/dp/1400052173)** > > The Immortal Life of Henrietta Lacks \[Skloot, Rebecca\] on Amazon.com. \*FREE\* shipping on qualifying offers. The Immortal Life of Henrietta Lacks ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [April 1, 2010, 5:57pm UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/19 "2010-04-01T17:57:10Z")
> [@Perciful](#): > > This is fascinating! How come I never heard of this before? Her identity was only recently revealed. Her cells have been common in labs since, well, not long after she donated them. I remember being told in one of my undergrad classes, about 10 years ago, about how we needed to be careful to not let them contaminate other cell cultures. ---
**Author:** ![Beadalin](https://avatars.discourse-cdn.com/v4/letter/b/3be4f8/32.png) [@Beadalin](https://boards.straightdope.com/u/Beadalin)\ **Post date:** [April 1, 2010, 6:24pm UTC](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509/20 "2010-04-01T18:24:35Z")
Of course, she didn’t actually donate them, which is part of the story. [Next page](https://boards.straightdope.com/t/animals-that-are-impossibly-hard-to-kill/534509.md?page=2)