Artificial jellyfish made from silicone and rat muscle (video) | Hacker News Reader

Artificial jellyfish made from silicone and rat muscle (video)

nature.com

131 pointsananyob20 comments

On a somewhat related note, as far as animals go, jelly fish are nuts. I mean they're barely animals at all. From wikipedia: "Most jellyfish do not have specialized digestive, osmoregulatory, central nervous, respiratory, or circulatory systems." and, "Jellyfish have no brain nor central nervous system". No brain? I mean come on. Jelly fish are floating piles of goo with absolutely no purpose or delight in life other than being floating piles of goo. It's made weirder by how big some of them get, "Jellyfish range from about one millimeter in bell height and diameter to nearly two meters in bell height and diameter; the tentacles and mouth parts usually extend beyond this bell dimension." Giant brainless animals roam the ocean looking to sting and absorb prey without ever really knowing they're even doing it. They're pretty much ocean zombies.

They're nuts, and are a great example of how evolution cares about nothing but survival.

[1]https://en.wikipedia.org/wiki/Jellyfish

This comment made my day :) one of the liveliest I've seen on hn

From the wikipedia article you linked to: Jellyfish have no brain nor central nervous system, but employ a loose network of nerves, located in the epidermis, which is called a "nerve net".

Though they are brainless, they do have enough reflexes to get by.

> Though they are brainless, they do have enough reflexes to get by.

It's surprising how well this applies to some people, too...

  > Giant brainless animals roam the ocean looking to sting 
  > and absorb prey without ever really knowing they're even
  > doing it. They're pretty much ocean zombies.

They do lack central nervous systems, but they're not entirely brainless. There's a non-encephalized diffuse neural ring that controls effectors which is sensitive to sensors input. Eerily, some jellyfish (box jellyfish, IIRC) have corneal eyes...

So, sure, these things are super stereotyped. But so are many higher organisms, even among good ol' vertebrates.

  > They're nuts, and are a great example of how evolution cares
  > about nothing but survival.

Please don't mistake evolution for natural selection. Evolution does not "care" about survival, it's just genetic change of biological populations over time, and natural selection is just one of the processes that produce evolutionary change.

Also, putting the emphasis on survival when referring to natural selection is a bit outdated. Please say "natural selection cares about nothing but differential reproduction of genotypes" instead if you don't want to sound so nineteenth-century :-) </pedantic_minutia>

from wikipedia: "Evolution is any change across successive generations in the inherited characteristics of biological populations."

from me: "Evolution(clearly biological) cares (a cute way of saying is effected by) about nothing but survival." The personification of evolution was perhaps a bit too cute, but I feel it's also a bit more inspiring than getting specific. Also, I can't see much of a difference between surviving and being naturally selected.

Please let me know what I'm missing.

First, I wasn't really complaining about the use of the verb "care". I think it's OK to abbreviate like that when talking about evolution, as long as we're aware we're anthropomorphizing.

Note that the definition from Wikipedia that you quoted says nothing about "survival". Death isn't even a requirement. You just need a change in the allele frequencies of a population to call it evolution.

With that survival line you were probably referring to natural selection, which is just one of the aspects of evolution, and again not a requirement for it. You can have evolution by genetic drift, for example. But even if you were just talking about natural selection, putting the emphasis on survival (and "nothing but survival") is incomplete and misleading. Death/survival don't need to play an important role in natural selection (though there are instances when it will, of course). For example, small differences in the average number of offspring already mean natural selection.

> We built an animal

No they didn't. They built a sheet of biological material that pulsates when placed in an electrical field. Animals reproduce, and hence adapt and evolve.

It's a neat gadget, but let's not get too carried away.

Yeah, but I think it's pretty interesting-- not because of the complexity of what's created, but because of the materials.

Agreed; this isn't much different than in bio where we would apply an electrical current to freshly amputated frogs legs (or heart) and watch them twitch. It's just a much more elaborate presentation. When it's swimming on it's own and reproducing, then I'll agree that they have created a new animal.

That is essentially what a jelly fish is.

To paraphrase another comment quoting wikipedia: "Most jellyfish do not have specialized digestive, osmoregulatory, central nervous, respiratory, or circulatory systems." and, "Jellyfish have no brain nor central nervous system."

I tend to agree that asserting they created an animal is a bit of a stretch. The creature doesn't obtain or maintain its structure through internally-encoded genes, nor does it maintain its behavior through an internal stimulus response mechanism. Its structure is grown around a polymer film, and its behavior is completely externally driven. At best, they have created a cyborg jellyfish-like thing.

At least they mentioned the grad student who did all the work!

“Morphologically, we’ve built a jellyfish. Functionally, we’ve built a jellyfish. Genetically, this thing is a rat,” You will never see that set of words in that order again.

I suppose it's an interesting article on its own, but I don't know that any of its suggested premises are true. The most obvious difference between this thing and a jellyfish is that a jellyfish doesn't need an electrical bath to exist in. There are other differences of course, but if they'd built a more analogous 'jellyfish robot' that at least functioned on its own, perhaps I'd be more receptive to the article's claims.

As it stands, the notion of 'testing heart medicine' on it seem exceedingly optimistic as it's fairly hard to test a heart in isolation. Also, this isn't a heart analogue, it's a jellyfish analogue. Also, a heart doesn't react to external impulses in the same way.

It's neat. There's no taking that away from it, but I just don't see how any of what the inventor claims is actually practical.

Yeah I agree with you that they haven't really created a jellyfish. It's not much more then a muscle that contracts in the same way as a jellyfish when subjected to an electrical charge.

But if you read it all you'll notice the following paragraph, "Parker’s lab works on creating artificial models of human heart tissues for regenerating organs and testing drugs, and the team built the medusoid as a way of understanding the “fundamental laws of muscular pumps”. It is an engineer’s approach to basic science: prove that you have identified the right principles by building something with them." - This in itself is a very nice feat.

The thing I took away from it was that they suspected that all muscular pumps work in a similar way.

> "My bet is that to get a muscular pump, the electrical activity has got to spread as a wavefront.”

They were then able to re-purpose heart muscle into a different form that still functioned as a muscular pump. Really quite interesting :)

I have a 4 year old, so naturally the idea of rat birds and raining food comes to mind. Kids movies, oy.

hmmm... I didn't realize that the world's jellyfish population was in such jeopardy that we needed to create an artificial one. Thankfully we have science looking out for us. o_0

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